Congratulations, You're Pregnant!

Congratulations, You're Pregnant!

Congratulations, You're Pregnant!

Let the decision-making begin. Choosing a health care provider to care for you and your baby during your pregnancy is one of the biggest decisions you'll make.

In the United States, women's choices once were limited to an obstetrician or a knowledgeable family doctor. But in recent years midwives became another alternative for women with low-risk, uncomplicated pregnancies.

In Europe, midwives assist at more than 70% of normal vaginal births. Though midwives delivered only 7% of American babies in 2003, that percentage has been increasing since 1975. But most Americans aren't sure what midwives do, how they're trained, or if they're even available. Is a midwife a viable option for you?

The History of Midwives

The word "midwife" comes from Old English and means "with woman." Midwives have helped women deliver babies since the beginning of history. References to midwives are found in ancient Hindu records, in Greek and Roman manuscripts, and even in the Bible.

As early as 1560, Parisian midwives had to pass a licensing examination and abide by regulations to practice. Not all midwives had this level of education, however. English midwives received little formal training and weren't licensed until 1902. America inherited the English model of midwifery.

Early American midwives usually learned their craft through apprenticeship and tradition. They were not educated about scientific advances in fighting infection through hygiene and drugs such as penicillin. By the early 20th century, women and their babies were more likely to die under the care of midwives than under the care of doctors.

Around this time, American medical doctors began a campaign against midwifery in the press, the courts, and Congress. They cited the poor outcomes for mothers and babies under the care of midwives. Doctors might also have viewed midwives as competition.

Diagnosis

Diagnosis

Further information: Obstetrics

Linea nigra in a woman at 22 weeks pregnant.

The beginning of pregnancy^[21] may be detected in a number of different ways, either by a pregnant woman without medical testing, or by using medical tests with or without the assistance of a medical professional.
Most pregnant women experience a number of symptoms,^[22] which can signify pregnancy. The symptoms can include nausea and vomiting, excessive tiredness and fatigue, cravings for certain foods that are not normally sought out, and frequent urination particularly during the night.
A number of early medical signs are associated with pregnancy.^[23][24] These signs typically appear, if at all, within the first few weeks after conception. Although not all of these signs are universally present, nor are all of them diagnostic by themselves, taken together they make a presumptive diagnosis of pregnancy. These signs include the presence of human chorionic gonadotropin (hCG) in the blood and urine, missed menstrual period, implantation bleeding that occurs at implantation of the embryo in the uterus during the third or fourth week after last menstrual period, increased basal body temperature sustained for over 2 weeks after ovulation, Chadwick's sign (darkening of the cervix, vagina, and vulva), Goodell's sign (softening of the vaginal portion of the cervix), Hegar's sign (softening of the uterus isthmus), and pigmentation of linea alba – Linea nigra, (darkening of the skin in a midline of the abdomen, caused by hyperpigmentation resulting from hormonal changes, usually appearing around the middle of pregnancy).^[23][24]
Pregnancy detection can be accomplished using one or more various pregnancy^[21] tests, which detect hormones generated by the newly formed placenta. Clinical blood and urine tests can detect pregnancy 12 days after implantation.^[25] Blood pregnancy tests are more accurate than urine tests.^[26] Home pregnancy tests are urine tests, and normally cannot detect a pregnancy until at least 12 to 15 days after fertilization. A quantitative blood test can determine approximately the date the embryo was conceived.
In the post-implantation phase, the blastocyst secretes a hormone named human chorionic gonadotropin, which in turn stimulates the corpus luteum in the woman's ovary to continue producing progesterone. This acts to maintain the lining of the uterus so that the embryo will continue to be nourished. The glands in the lining of the uterus will swell in response to the blastocyst, and capillaries will be stimulated to grow in that region. This allows the blastocyst to receive vital nutrients from the woman.
Despite all the signs, some women may not realize they are pregnant until they are quite far along in their pregnancy. In some cases, a few women have not been aware of their pregnancy until they begin labour. This can be caused by many factors, including irregular periods (quite common in teenagers), certain medications (not related to conceiving children), and obese women who disregard their weight gain. Others may be in denial of their situation.
An early sonograph can determine the age of the pregnancy fairly accurately. In practice, doctors typically express the age of a pregnancy (i.e., an "age" for an embryo) in terms of "menstrual date" based on the first day of a woman's last menstrual period, as the woman reports it. Unless a woman's recent sexual activity has been limited, she has been charting her cycles, or the conception is the result of some types of fertility treatment (such as IUI or IVF), the exact date of fertilization is unknown. Without symptoms such as morning sickness, often the only visible sign of a pregnancy is an interruption of the woman's normal monthly menstruation cycle, (i.e., a "late period"). Hence, the "menstrual date" is simply a common educated estimate for the age of a fetus, which is an average of 2 weeks later than the first day of the woman's last menstrual period. The term "conception date" may sometimes be used when that date is more certain, though even medical professionals can be imprecise with their use of the two distinct terms. The due date can be calculated by using Naegele's rule. The expected date of delivery may also be calculated from sonogram measurement of the fetus. This method is slightly more accurate than methods based on LMP.^[27]
Diagnostic criteria are: Women who have menstrual cycles and are sexually active, a period delayed by a few days or weeks is suggestive of pregnancy; elevated B-hcG to around 100,000 mIU/mL by 10 weeks of gestation.^[2]

First trimester

First trimester

First trimester

Traditionally, doctors have measured pregnancy from a number of convenient points, including the day of last menstruation, ovulation, fertilization, implantation and chemical detection. In medicine, pregnancy is often defined as beginning when the developing embryo becomes implanted into the endometrial lining of a woman's uterus. In some cases where complications may have arisen, the fertilized egg might implant itself in the fallopian tubes, the cervix, the ovary or in the abdomen causing an ectopic pregnancy. In the case of an ectopic pregnancy there is no way for the pregnancy to progress normally. If left untreated, it can cause harm and possibly death for the mother when a rupture occurs. Sometimes it will go away on its own but otherwise a surgical procedure or medicine is given to remove the tubal pregnancy since there is no way of the pregnancy being able to continue safely.^[28] Most pregnant women do not have any specific signs or symptoms of implantation, although it is not uncommon to experience minimal bleeding at implantation. Some women will also experience cramping during their first trimester. This is usually of no concern unless there is spotting or bleeding as well. After implantation the uterine endometrium is called the decidua. The placenta, which is formed partly from the decidua and partly from outer layers of the embryo, connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. The umbilical cord is the connecting cord from the embryo or fetus to the placenta. The developing embryo undergoes tremendous growth and changes during the process of fetal development.

Morning sickness occurs in about seventy percent of all pregnant women and typically improves after the first trimester.^{[29][dead link]} Although described as "morning sickness", women can experience this nausea during afternoon, evening, and throughout the entire day.

In the first 12 weeks of pregnancy, the nipples and areolas darken due to a temporary increase in hormones.^[30]

The first 12 weeks of pregnancy are considered to make up the first trimester. The first two weeks from the first trimester are calculated as the first two weeks of pregnancy even though the pregnancy does not actually exist. These two weeks are the two weeks before conception and include the woman's last period.

The third week is the week in which fertilization occurs and the 4th week is the period when implantation takes place. In the 4th week, the fecundated egg reaches the uterus and burrows into its wall which provides it with the nutrients it needs. At this point, the zygote becomes a blastocyst and the placenta starts to form. Moreover, most of the pregnancy tests may detect a pregnancy beginning with this week.

The 5th week marks the start of the embryonic period. This is when the baby's brain, spinal cord, heart and other organs begin to form.^[31] At this point the embryo is made up of three layers, of which the top one (called the ectoderm) will give rise to the baby's outermost layer of skin, central and peripheral nervous systems, eyes, inner ear, and many connective tissues.^[31] The heart and the beginning of the circulatory system as well as the bones, muscles and kidneys are made up from the mesoderm (the middle layer). The inner layer of the embryo will serve as the starting point for the development of the baby's lungs, intestine and bladder. This layer is referred to as the endoderm. A baby at 5 weeks is normally between ¹⁄₁₆ and ¹⁄₈ inch (1.6 and 3.2 mm) in length.

In the 6th week, the baby will be developing basic facial features and its arms and legs start to grow. At this point, the embryo is usually no longer than ¹⁄₆ to ¹⁄₄ inch (4.2 to 6.3 mm). In the following week, the brain, face and arms and legs quickly develop. In the 8th week, the baby starts moving and in the next 3 weeks, the baby's toes, neck and genitals develop as well. According to the American Pregnancy Association, by the end of the first trimester, the fetus will be about 3 inches (76 mm) long and will weigh approximately 1 ounce (28 g).^[32]

Second trimester

Weeks 13 to 28 of the pregnancy are called the second trimester. Most women feel more energized in this period, and begin to put on weight as the symptoms of morning sickness subside and eventually fade away.

In the 20th week, the uterus, the muscular organ that holds the developing fetus, can expand up to 20 times its normal size during pregnancy. Although the fetus begins to move and takes a recognizable human shape during the first trimester, it is not until the second trimester that movement of the fetus, often referred to as "quickening", can be felt. This typically happens in the fourth month, more specifically in the 20th to 21st week, or by the 19th week if the woman has been pregnant before. However, it is not uncommon for some women not to feel the fetus move until much later. The placenta fully functions at this time and the fetus makes insulin and urinates. The reproductive organs distinguish the fetus as male or female.

Third trimester

Comparison of growth of the abdomen between 26 weeks and 40 weeks gestation.

Final weight gain takes place, which is the most weight gain throughout the pregnancy. The fetus will be growing the most rapidly during this stage, gaining up to 28 g per day. The woman's belly will transform in shape as the belly drops due to the fetus turning in a downward position ready for birth. During the second trimester, the woman's belly would have been very upright, whereas in the third trimester it will drop down quite low, and the woman will be able to lift her belly up and down. The fetus begins to move regularly, and is felt by the woman. Fetal movement can become quite strong and be disruptive to the woman. The woman's navel will sometimes become convex, "popping" out, due to her expanding abdomen. This period of her pregnancy can be uncomfortable, causing symptoms like weak bladder control and backache. Movement of the fetus becomes stronger and more frequent and via improved brain, eye, and muscle function the fetus is prepared for ex utero viability. The woman can feel the fetus "rolling" and it may cause pain or discomfort when it is near the woman's ribs and spine.

There is head engagement in the third trimester, that is, the fetal head descends into the pelvic cavity so that only a small part (or none) of it can be felt abdominally. The perenium and cervix are further flattened and the head may be felt vaginally.^[33] Head engagement is known colloquially as the baby drop, and in natural medicine as the lightening because of the release of pressure on the upper abdomen and renewed ease in breathing. However, it severely reduces bladder capacity, increases pressure on the pelvic floor and the rectum, and the mother may experience the perpetual sensation that the fetus will "fall out" at any moment.^[34]

It is during this time that a baby born prematurely may survive. The use of modern medical intensive care technology has greatly increased the probability of premature babies surviving, and has pushed back the boundary of viability to much earlier dates than would be possible without assistance.^[35] In spite of these developments, premature birth remains a major threat to the fetus, and may result in ill health in later life, even if the baby survives.

Embryonic and fetal development

Embryonic and fetal development

Prenatal development is divided into two primary biological stages. The first is the embryonic stage, which lasts for about two months. At this point, the fetal stage begins. At the beginning of the fetal stage, the risk of miscarriage decreases sharply,^[36] all major structures including the head, brain, hands, feet, and other organs are present, and they continue to grow and develop. When the fetal stage commences, a fetus is typically about 30 mm (1.2 inches) in length, and the heart can be seen beating via sonograph; the fetus bends the head, and also makes general movements and startles that involve the whole body.^[37] Some fingerprint formation occurs from the beginning of the fetal stage.^[38]

Electrical brain activity is first detected between the 5th and 6th week of gestation, though this is still considered primitive neural activity rather than the beginning of conscious thought, something that develops much later in fetation. Synapses begin forming at 17 weeks, and at about week 28 begin to multiply at a rapid pace which continues until 3–4 months after birth. It is not until week 23 that the fetus can survive, albeit with major medical support, outside of the womb, because it does not possess a sustainable human brain until that time.^[39]

Embryo at 4 weeks after fertilization[40]	Fetus at 8 weeks after fertilization[41]	Fetus at 18 weeks after fertilization[42]	Fetus at 38 weeks after fertilization[43]
Relative size in 1st month (simplified illustration)	Relative size in 3rd month (simplified illustration)	Relative size in 5th month (simplified illustration)	Relative size in 9th month (simplified illustration)

One way to observe prenatal development is via ultrasound images. Modern 3D ultrasound images provide greater detail for prenatal diagnosis than the older 2D ultrasound technology.^[44] While 3D is popular with parents desiring a prenatal photograph as a keepsake,^[45] both 2D and 3D are discouraged by the FDA for non-medical use,^{[46][dead link]} but there are no definitive studies linking ultrasound to any adverse medical effects.^[47] The following 3D ultrasound images were taken at different stages of pregnancy:

75-mm fetus (about 14 weeks gestational age)

Fetus at 17 weeks

Fetus at 20 weeks

Some people are confused about the differences between an ultrasound and a sonogram. An ultrasound is the actual machine that lets you observe pregnancy. A sonogram is the image of the baby that the ultrasound produces. 4D Ultrasounds take 3D sonograms. Some people refer to the procedure as prenatal imaging, 3D imaging, a 3D scan, or 4D scan.

Physiological changes

Melasma pigment changes to the face due to pregnancy

During pregnancy, the woman undergoes many physiological changes, which are entirely normal, including cardiovascular, hematologic, metabolic, renal and respiratory changes that become very important in the event of complications. The body must change its physiological and homeostatic mechanisms in pregnancy to ensure the fetus is provided for. Increases in blood sugar, breathing and cardiac output are all required. Levels of progesterone and oestrogens rise continually throughout pregnancy, suppressing the hypothalamic axis and subsequently the menstrual cycle. The woman and the placenta also produce many hormones.

Managemen

Prenatal medical care is the medical and nursing care recommended for women before and during pregnancy. The aim of good prenatal care is to detect any potential problems early, to prevent them if possible (through recommendations on adequate nutrition, exercise, vitamin intake etc.), and to direct the woman to appropriate specialists, hospitals, etc. if necessary.

Nutritis

A balanced, nutritious diet is an important aspect of a healthy pregnancy. Eating a healthy diet, balancing carbohydrates, fat, and proteins, and eating a variety of fruits and vegetables, usually ensures good nutrition. Those whose diets are affected by health issues, religious requirements, or ethical beliefs may choose to consult a health professional for specific advice.

Adequate periconceptional folic acid (also called folate or Vitamin B₉) intake has been proven to limit fetal neural tube defects, preventing spina bifida, a very serious birth defect. The neural tube develops during the first 28 days of pregnancy, explaining the necessity to guarantee adequate periconceptional folate intake.^[48][49] Folates (from folia, leaf) are abundant in spinach (fresh, frozen, or canned), and are found in green leafy vegetables e.g. salads, beets, broccoli, asparagus, citrus fruits and melons, chickpeas (i.e. in the form of hummus or falafel), and eggs. In the United States and Canada, most wheat products (flour, noodles) are fortified with folic acid.^[50]

DHA omega-3 is a major structural fatty acid in the brain and retina, and is naturally found in breast milk. It is important for the woman to consume adequate amounts of DHA during pregnancy and while nursing to support her well-being and the health of her infant. Developing infants cannot produce DHA efficiently, and must receive this vital nutrient from the woman through the placenta during pregnancy and in breast milk after birth.^[51]

Several micronutrients are important for the health of the developing fetus, especially in areas of the world where insufficient nutrition is prevalent.^[52] In developed areas, such as Western Europe and the United States, certain nutrients such as Vitamin D and calcium, required for bone development, may require supplementation.^[53][54][55]

Dangerous bacteria or parasites may contaminate foods, particularly Listeria and toxoplasma, toxoplasmosis agent. Careful washing of fruits and raw vegetables may remove these pathogens, as may thoroughly cooking leftovers, meat, or processed meat. Soft cheeses may contain Listeria; if milk is raw, the risk may increase. Cat feces pose a particular risk of toxoplasmosis. Pregnant women are also more prone to Salmonella infections from eggs and poultry, which should be thoroughly cooked. Practicing good hygiene in the kitchen can reduce these risks.^[56]

Weight gain

Caloric intake must be increased to ensure proper development of the fetus. The amount of weight gained during a single pregnancy varies among women. The Institute of Medicine recommends an overall pregnancy weight gain for women starting pregnancy at a normal weight, with a body mass index of 18.5-24.9, of 25-35 pounds (11.4-15.9 kg).^[57] Women who are underweight, with a BMI of less than 18.5, may need to gain between 28-40 lbs. Overweight women are advised to gain between 15-25 lbs, whereas an obese woman may expect to gain between 11-20 lbs. Doctors and dietitians may make different, or more individualized, recommendations for specific patients, based on factors including low maternal age, nutritional status, fetal development, and morbid obesity.

During pregnancy, insufficient or excessive weight gain can compromise the health of the mother and fetus. All women are encouraged to choose a healthy diet regardless of pre-pregnancy weight. Exercise during pregnancy, such as walking and swimming, is recommended for healthy pregnancies. Exercise has notable health benefits for both mother and baby, including preventing excessive weight gain.^[58]

Immune tolerance

The fetus inside a pregnant woman may be viewed as an unusually successful allograft, since it genetically differs from the woman.^[59] In the same way, many cases of spontaneous abortion may be described in the same way as maternal transplant rejection.^[59]

Medication use

Drugs used during pregnancy can have temporary or permanent effects on the fetus. Therefore many physicians would prefer not to prescribe for pregnant women, the major concern being over teratogenicity of the drugs.

Drugs have been classified into categories A,B,C,D and X based on the Food and Drug Administration (FDA) rating system to provide therapeutic guidance based on potential benefits and fetal risks. Drugs like multivitamins that have demonstrated no fetal risks after controlled studies in humans are classified as Category A. On the other hand drugs like thalidomide with proven fetal risks that outweigh all benefits are classified as Category X.^[60]

Initiation last menstruation

Initiation last menstruation

Initiation

The initial stages of human embryogenesis.

Pregnancy occurs as the result of the female gamete or oocyte merging with the male gamete, spermatozoon, in a process referred to, in medicine, as fertilization, or more commonly known as "conception". After the point of fertilization, it is referred to as a zygote or fertilized egg. The fusion of male and female gametes usually occurs through the act of sexual intercourse, resulting in spontaneous pregnancy. However, the advent of artificial insemination and in vitro fertilisation have also made achieving pregnancy possible in cases where sexual intercourse does not result in fertilization (e.g., through choice or male/female infertility).
The process of fertilization occurs in more than a single step, and the interruption of any of these can lead to a failure. Therefore, what is commonly known as "conception" is much more than the fusion between the female gamete and male spermatozoon. Through fertilization, the egg and sperm are saved: the egg is activated to begin its developmental program, and the haploid nuclei of the two gametes come together to form the genome of a new diploid organism ^[9]
At the very beginning of the process, the sperm undergoes a series of changes which makes pregnancy likely to occur. As freshly ejaculated sperm is unable or poorly able to fertilize,^[10] the sperm undergoes the phenomenon called capacitation. It is estimated that during the ejaculation, 300,000,000 sperm are released, from which only 200 reach the oviduct. Capacitation is the process through which the spermatozoon is prepared for the merging with the egg. Capacitation occurs in 5 to 6 hours and it takes place once the sperm reaches the vagina. This is also the process through which the spermatozoon becomes hyperactivated and prepared for the acrosome reaction. In order to be able to fecundate the egg, the sperm must get through the coat surrounding the egg, the so called "zona pellucida". Once the zona pellucida is penetrated, the sperm is able to reach the oocyte. However in order to get through the egg's coat, the sperm undergoes an acrosome reaction that provides it with an enzymatic drill which is able to penetrate the zona pellucida. The acrosome itself is a modified lysosome, situated on the anterior part of the head of the sperm.
Once a sperm penetrates the zona pellucida, it binds to and fuses with the plasma membrane of the oocyte. Binding occurs at the posterior (post-acrosomal) region of the sperm head.^[10] After binding occurs, the egg must also undergo a series of metabolic and physical changes which may influence the further development of the zygote. These changes are called in medicine egg activation, mainly because prior to fertilization, the egg is in a latent state.
Methods to assist reproduction also include intracytoplasmic sperm injection, gamete intrafallopian transfer (GIFT), zygote intrafallopian transfer (ZIFT), and embryo cryopreservation (frozen fertilized egg and sperm). These techniques are considered as alternatives to get pregnant by women who have tried unsuccessfully for at least one year. It is estimated that in the United States, more than 6 million adults, or 10% of the adult population, are affected by infertility.^[11]

Prenatal period

Prenatal defines the period occurring "around the time of birth", specifically from 22 completed weeks (154 days) of gestation (the time when birth weight is normally 500 g) to 7 completed days after birth.^[12]
Legal regulations in different countries include gestation age beginning from 16 to 22 weeks (5 months) before birth.

Postnatal period

Main article: Postnatal

The postnatal period begins immediately after the birth of a child and then extends for about six weeks. During this period, the mother's body returns to prepregnancy conditions as far as uterus size and hormone levels are concerned.

Perinatal period

The perinatal period is immediately before to after birth. Depending on the definition, it starts between the 20th to 28th week of gestation and ends between 1 to 4 weeks after birth (the word "perinatal" is a hybrid of the Greek "peri-" meaning 'around or about' and "natal" from the Latin "natus" meaning "birth.").

Duration

The expected date of delivery (EDD) is 40 weeks counting from the first day of the last menstrual period (LMP), and birth usually occurs between 37 and 42 weeks.^[13] The actual pregnancy duration is typically 38 weeks after conception. Though pregnancy begins at conception, it is more convenient to date from the first day of a woman's last menstrual period, or from the date of conception if known. Starting from one of these dates, the expected date of delivery can be calculated using the Naegele's rule for estimating date of delivery. A more accurate and sophisticated algorithm takes into account other variables, such as whether this is the first or subsequent child (i.e., pregnant woman is a primip or a multip, respectively), ethnicity, parental age, length of menstrual cycle, and menstrual regularity.
Pregnancy is considered "at term" when gestation attains 37 complete weeks but is less than 42 (between 259 and 294 days since LMP). Events before completion of 37 weeks (259 days) are considered preterm; from week 42 (294 days) events are considered postterm.^[14] When a pregnancy exceeds 42 weeks (294 days), the risk of complications for both the woman and the fetus increases significantly.^[13][15] As such, obstetricians usually prefer to induce labour, in an uncomplicated pregnancy, at some stage between 41 and 42 weeks.^[16][17]
Recent medical literature prefers the terminology preterm and postterm to premature and postmature. preterm and postterm are unambiguously defined as above, whereas premature and postmature have historical meaning and relate more to the infant's size and state of development rather than to the stage of pregnancy.^[18][19]
Fewer than 5% of births occur on the due date; 50% of births are within a week of the due date, and almost 90% within 2 weeks.^{[unreliable medical source?][20]} It is much more useful and accurate, therefore, to consider a range of due dates, rather than one specific day, with some online due date calculators providing this information.
Accurate dating of pregnancy is important, because it is used in calculating the results of various prenatal tests (for example, in the triple test). A decision may be made to induce labour if a fetus is perceived to be overdue. Furthermore, if LMP and ultrasound dating predict different respective due dates, with the latter being later, this might signify slowed fetal growth and therefore require closer review.
The age of viability has been receding because of continued medical progress. Whereas it used to be 28 weeks, it has been brought back to as early as 23, or even 22 weeks in some countries.

Childbirth

Main article: Childbirth

Childbirth is the process whereby an infant is born. It is considered by many^[who?] to be the beginning of the infant's life, and age is defined relative to this event in most cultures.
A woman is considered to be in labour when she begins experiencing regular uterine contractions, accompanied by changes of her cervix — primarily effacement and dilation. While childbirth is widely experienced as painful, some women do report painless labours, while others find that concentrating on the birth helps to quicken labour and lessen the sensations. Most births are successful vaginal births, but sometimes complications arise and a woman may undergo a cesarean section.
During the time immediately after birth, both the mother and the baby are hormonally cued to bond, the mother through the release of oxytocin, a hormone also released during breastfeeding.

ADAPTASI FISIOLOGIS BAYI BARU LAHIR

ADAPTASI FISIOLOGIS BAYI BARU LAHIR

I.         PERUBAHAN SISTEM PERNAFASAN

Perkembangan paru-paru

Paru-paru berasal dari titik tumbuh yang muncul dari pharynx, yang bercabang dan kemudian bercabang kembali membentuk struktur percabangan bronkus. Proses ini terus berlanjut setelah kelahiran hingga sekitar usia 8 tahun sampai jumlah bronkiolus dan alveolus akan sepenuhnya berkembang, walaupun janin memperlihatkan adanya bukti gerakan napas sepanjang trimester kedua dan ketiga (Varney’s, halaman 551). Ketidakmatangan paru-paru terutama akan mengurangi peluang kelangsungan hidup bayi baru lahir sebelum usia kehamilan 24 minggu, yang disebabkan oleh keterbatasan permukaan alveolus, ketidakmatangan system kapiler paru-paru dan tidak mencukupinya jumlah surfaktan.

Awal adanya nafas

Dua factor yang berperan pada rangsangan napas pertama bayi.

1.       Hipoksia pada akhir persalinan dan rangsangan fisik lingkungan luar rahim yang merangsang pusat pernapasan di otak.

2.       Tekanan terhadap rongga dada, yang terjadi karena kompresi paru-paru selama persalinan, yang merangsang masuknya udara kedalam paru-paru secara mekanis.

Interaksi antara system pernapasan, kardiovaskuler dan susunan saraf pusat menimbulkan pernapasan yang teratur dan berkesinambungan serta denyut yang diperlukan untuk kehidupan. Jadi system-sistem harus berfungsi secara normal.

Surfaktan dan upaya respirasi untuk bernafas

Upaya pernapasan pertama seorang bayi berfungsi untuk :

1.       Mengeluarkan cairan dalam paru-paru

2.       Mengembangkan jaringan alveolus paru-paru untuk pertama kali

Agar alveolus dapat berfungsi, harus terdapat surfaktan yang cukup dan aliran darah ke paru-paru. Produksi surfaktan dimulai pada 20 minggu kehamilan dan jumlahnya akan meningkat sampai paru-paru matang sekitar 30-34 minggu kehamilan. Surfaktan ini mengurangi tekanan permukaan paru dan membantu untuk menstabilkan dinding alveolus sehingga tidak kolaps pada akhir pernapasan

Tanpa surfaktan, alveoli akan kolaps setiap saat setelah akhir setiap pernapasan, yang menyebabkan sulit bernapas. Peningkatan kebutuhan energi ini memerlukan penggunaan lebih banyak oksigen dan glukosa. Peningkatan kebutuhan energi ini memerlukan penggunaan lebih banyak oksigen dan glukosa. Berbagai peningkatan ini menyebabkan stress pada bayi yang sebelumnya sudah terganggu.

Dari cairan menuju udara

Bayi cukup bulan, mempunyai cairan di dalam paru-parunya. Pada saat bayi melalui jalan lahir selama persalinan, sekitar sepertiga cairan ini diperas keluar dari paru-paru. Seorang bayi yang dilahirkan melalui seksio sesaria kehilangan keuntungan dari kompresi rongga dada ini dan dapat menderita paru-paru basah dalam jangka waktu lebih lama. Dengan beberapa kali tarikan napas pertama, udara memenuhi ruangan trakea dan bronkus bayi baru lahir. Dengan sisa cairan di dalam paru-paru dikeluarkan dari paru dan diserap oleh pembuluh limfe dan darah. Semua alveolus paru-paru akan berkembang terisi udara sesuai dengan perjalanan waktu.

Funsi system pernapasan dalam kaitanya dengan fungsi kardiovaskuler

Oksigenasi yang memadai merupakan factor yang sangat penting dalam mempertahankan kecukupan pertukaran udara. Jika terdapat hipoksia, pembuluh darah paru-paru  akan mengalami vasokonstriksi. Pengerutan pembuluh ini berarti tidak ada pembuluh darah yang terbuka guna menerima oksigen yang berada dalam alveoli, sehingga menyebabkan penurunan oksigenasi jaringan, yang akan memperburuk hipoksia.

Peningkatan aliran darah paru-paru akan memperlancar pertukaran gas dalam alveolus dan menghilangkan cairan paru-paru. Peningkatan aliran darah ke paru-paru akan mendorong terjadinya peningkatan sirkulasi limfe dan membantu menghilangkan cairan paru-paru dan merangsang perubahan sirkulasi janin menjadi sirkulasi luar rahim.

II.      PERUBAHAN SISTEM SIRKULASI

Setelah lahir, darah bayi baru lahir harus melewati paru untuk mengambil oksigen dan mengadakan sirkulasi melalui tubuh guna mengantarkan oksigen ke jaringan. Untuk membuat sirkulasi yang baik guna mendukung kehidupan luar rahim, harus terjadi dua perubahan besar:

1.       Penutupan foramen ovale pada atrium jantung

2.       Penutupan duktus arteriosus antara arteri paru-paru dan aorta.

Perubahan sirkulasi ini terjadi akibat perubahan tekanan pada seluruh system pembuluh tubuh. Ingat hokum yang menyatakan bahwa darah akan mengalir pada daerah-daerah yang mempunyai resistensi yang kecil. Jadi perubahan-perubahan tekanan langsung berpengaruh pada aliran darah.

Oksigen menyebabkan system pembuluh  mengubah tekanan dengan cara mengurangi atau meningkatkan resistensinya, sehingga mengubah aliran darah. Hal ini terutama penting kalau kita ingt bahwa sebagian besar kematian dini bayi baru lahir berkaitan dengan oksigen (asfiksia).

Dua peristiwa yang mengubah tekanan dalam system pembuluh darah :

1.       Pada saat tali pusat dipotong, resistensi pembuluh sistemik meningkat dan tekanan atrium kanan menurun. Tekanan atrium kanan menurun karena berkurangnya aliran darah ke atrium kanan tersebut. Hal ini menyebabkan penurunan volume dan tekanan atrium kanan itu sendiri. Kedua kejadian ini membantu darah dengan kandungan oksigen sedikit mengalir ke paru-paru untuk menjalani proses oksigenasi ulang.

2.       Pernapasan pertama menurunkan resistensi pembuluh darah paru-paru dan meningkatkan tekanan atrium kanan. Oksigen pada pernapasan pertama ini menimbulkan relaksasi dan terbukanya system pembuluh darah paru-paru (menurunkan resistensi pembuluh darah paru-paru). Peningkatan sirkulasi ke paru-paru mengakibatkan peningkatan volume darah dan tekanan pada atrium kanan. Dengan peningkatan volume darah dan tekanan pada atrium kiri, foramen ovale secara fungsional akan menutup.

Vena umbilicus, duktus venosus dan arteri hipogastrika dari tali pusat menutup secara funsional dalam beberapa menit setelah lahir dan setelah tali pusat diklem. Penutupan anatomi jaringan fibrosa berlangsung dalam 2-3 bulan

III.    PERUBAHAN SISTEM TERMOREGULASI

Bayi baru lahir belum dapat mengatur suhu tubuh mereka, sehingga akan mengalami stress dengan adanya perubahan-perubahan lingkungan. Pada saat bayi meninggalkan lingkungan rahim ibu yang hangat, bayi tersebut kemudian masuk ke dalam lingkungan ruang bersalin yang jauh lebih dingin. Suhu dingin ini menyebabkan air ketuban menguap lewat kulit, sehingga mendinginkan darah bayi.

Pada lingkungan yang dingin, pembentukan suhu tanpa mekanisme menggigil merupakan usaha utama seorang bayi yang kedinginan untuk mendapatkan kembali panas tubuhnya. Pembentukan suhu tanpa menggigil ini merupakan hasil penggunaan lemak coklat terdapat di seluruh tubuh, dan mereka mampu meningkatkan panas tubuh sampai 100 %. Untuk membakar lemak coklat, seorang bayi harus menggunakan glukosa guna mendapatkan energi yang akan mengubah lemak menjadi panas. Lemak coklat tidak dapat diproduksi ulang oleh bayi baru lahir dan cadangan lemak coklat ini akan habis dalam waktu singkat dengan adanya stress dingin. Semakin lama usia kehamilan, semakin banyak persediaan lemak coklat bayi.

Jika seorang bayi kedinginan, dia akan mulai mengalami hipoglikemia, hipoksia dan asidosis. Oleh karena itu, upaya pencegahan kehilangan panas merupakan prioritas utama dan bidan berkewajiban untuk meminimalkan kehilangan panas pada bayi baru lahir.

Disebut sebagai hipotermia bila suhu tubuh turun dibawah 36⁰  C. Suhu normal pada neonatus adalah 36 ⁵ – 37⁰ C.

Bayi baru lahir mudah sekali terkena hipotermia yang disebabkan oleh:

1.       Pusat pengaturan suhu tubuh pada bayi belum berfungsi dengan sempurna

2.       Permukaan tubuh bayi relative lebih luas

3.       Tubuh bayi terlalu kecil untuk memproduksi dan menyimpan panas

4.       Bayi belum mampu mengatur possisi tubuh dan pakaiannya agar ia tidak kedinginan.

Hipotermia dapat terjadi setiap saat apabila suhu disekeliling bayi rendah dan upaya mempertahankan suhu tubuh tidak diterapkan secara tepat, terutama pada masa stabilisasi yaitu 6 – 12 jam pertama setelah lahir. Misal: bayi baru lahir dibiarkan basah dan telanjang selama menunggu plasenta lahir atau meskipun lingkungan disekitar bayi cukup hangat namun bayi dibiarkan telanjang atau segera dimandikan.

Gejala hipotermia:

1.       Sejalan dengan menurunnya suhu tubuh, bayi menjadi kurang aktif, letargis, hipotonus, tidak kuat menghisap ASI dan menangis lemah.

2.       Pernapasan megap-megap dan lambat, denyut jantung menurun.

3.       Timbul sklerema : kulit mengeras berwarna kemerahan terutama dibagian punggung, tungkai dan lengan.

4.       Muka bayi berwarna merah terang

5.       Hipotermia menyebabkan terjadinya perubahan metabolisme tubuh yang akan berakhir dengan kegagalan fungsi jantung, perdarahan terutama pada paru-paru, ikterus dan kematian.

Mekanisme terjadinya Hipotermia:

Hipotermia pada bayi baru lahir timbul karena penurunan suhu tubuh yang dapat terjadi melalui:

1.       Radiasi : Yaitu panas tubuh bayi memancar kelingkungan sekitar bayi yang lebih dingin, misal : BBL diletakkan ditempat yang dingin.

2.       Evaporasi : Yaitu cairan/air ketuban yang membasahi kulit bayi menguap, misal : BBL tidak langsung dikeringkan dari air ketuban.

3.       Konduksi : Yaitu pindahnya panas tubuh bayi karena kulit bayi langsung kontak dengan permukaan yang lebih dingin, misal : popok/celana basah tidak langsung diganti.

4.       Konveksi : Yaitu hilangnya panas tubuh bayi karena aliran udara sekeliling bayi, misal : BBL diletakkan dekat pintu/jendela terbuka.

IV.    PERUBAHAN SISTEM METABOLISME

Untuk memfungsikan otak memerlukan glukosa dalam jumlah tertentu. Dengan tindakan penjepitan tali pusat dengan klem pada saat lahir seorang bayi harus mulai mempertahankan kadar glukosa darahnya sendiri. Pada setiap baru lahir, glukosa darah akan turun dalam waktu cepat (1 sampai 2 jam).

Koreksi penurunan gula darah dapat dilakukan dengan 3 cara :

1.       Melalui penggunaan ASI (bayi baru lahir sehat harus didorong untuk menyusu ASI secepat mungkin setelah lahir).

2.       Melalui penggunaan cadangan glikogen (glikogenesis)

3.       Melalui pembuatan glukosa dari sumber lain terutama lemak (glukoneogenesis).

Bayi baru lahir yang tidak dapat mencerna makanan dalam jumlah yang cukup akan membuat glukosa dari glikogen (glikogenolisis). Hal ini hanya terjadi jika bayi mempunyai persediaan glikogen yang cukup. Seorang bayi yang sehat akan menyimpan glukosa sebagai glikogen, terutama dalam hati, selama bulan-bulan terakhir kehidupan dalam rahim. Seorang bayi yang mengalami hipotermia pada saat lahir yang mengakibatkan hipoksia akan menggunakan persediaan glikogen dalam jam pertama kelahiran. Inilah sebabnya mengapa sangat penting menjaga semua bayi dalam keadaan hangat. Perhatikan bahwa keseimbangan glukosa  tidak sepenuhnya tercapai hingga 3-4 jam pertama pada bayi cukup bulan yang sehat. Jika semua persediaan digunakan pada jam pertama maka otak bayi dalam keadaan beresiko. Bayi baru lahir kurang bulan, lewat bulan, hambatan pertumbuhan dalam rahim dan distress janin merupakan resiko utama, karena simpanan energi berkurang atau digunakan sebelum lahir.

Gejala-gejala hipoglikemia bisa tidak jelas dan tidak khas meliputi : kejang-kejang halus, sianosis, apnu, tangis lemah, letargis, lunglai dan menolak makanan. Bidan harus selalu ingat bahwa hipoglikemia dapat tanpa gejala pada awalnya. Akibat jangka panjang hipoglikemia ialah kerusakan yang meluas di seluruh sel-sel otak.

V.       PERUBAHAN SISTEM GASTROINTESTINAL

Sebelum lahir, janin cukup bulan akan mulai menghisap dan menelan. Refleks gumoh dan refleks batuk yang matang sudah terbentuk dengan baik pada saat lahir.

Kemampuan bayi baru lahir cukup bulan untuk menelan dan mencerna makanan (selain susu) masih terbatas. Hubungan antara esophagus bawah dan lambung masih belum sempurna yang mengakibatkan “gumoh” pada bayi baru lahir dan neonatus. Kapasitas lambung sendiri sangat terbatas, kurang dari 30 cc untuk seorang bayi baru lahir cukup bulan. Kapasitas lambung ini akan bertambah secara lambat bersamaan dengan tumbuhnya bayi baru lahir. Pengaturan makan yang sering oleh bayi sendiri penting contohnya memeberi ASI on demand.

Usus bayi masih belum matang sehingga tidak mampu melindungi dirinya sendiri dari zat-zat berbahaya kolon. Pada bayi baru lahir kurang efisien dalam mempertahankan air disbanding orang dewasa, sehingga menyebabkan diare yang lebih serius pada neonatus.

VI.    PERUBAHAN SISTEM KEKEBALAN TUBUH

Sistem imunitas bayi baru lahir masih belum matang, sehingga menyebabkan neonatus rentan terhadap berbagai infeksi dan alergi. Sistem imunitas yang matang akan memberikan kekebalan alami maupun yang didapat.

Kekebalan alami terdiri dari struktur pertahanan tubuh yang mencegah atau meminimalkan infeksi. Berikut beberapa contoh kekebalan alami meliputi:

1.       Perlindungan oleh kulit membrane mukosa.

2.       Fungsi saringan saluran napas.

3.       Pembentukan koloni mikroba oleh kulit dan usus

4.       Perlindungan kimia oleh lingkungan asam lambung.

Kekebalan alami juga disediakan pada tingkat sel oleh sel darah yang membantu bayi baru lahir membunuh mikroorganisme asing. Tetapi pada bayi baru lahir sel-sel darah ini masih belum matang, artinya bayi baru lahir tersebut belum mampu melokalisasi dan memerangi infeksi secara efisien.

Kekebalan yang didapat akan muncul kemudian. Bayi baru lahir yang lahir dengan kekebalan pasif mengandung banyak virus dalam tubuh ibunya. Reaksi antibody keseluruhan terhadap antigen asing masih belum bisa dilakukan sampai awal kehidupan anak. Salah satu tuges utama selama masa bayi dan balita adalah pembentukan system kekebalan tubuh.

Karena adanya defisiensi kekebalan alami dan didapat ini, bayi baru lahir sangat rentan terhadap infeksi. Reaksi bayi baru lahir terhadap infeksi masih lemah dan tidak memadai. Oleh karena itu, pencegahan terhadap mikroba (seperti pada praktek persalinan yang aman dan menyusui ASI dini terutama kolostrum) dan detekdi dini serta pengobatan dini infeksi menjadi sangat penting.