Pregnancy
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Edited By: Shana McKibbin
Includes Pregnancy from Wikipedia http://en.wikipedia.org/wiki/Pregnancy
Pregnancy
ISBN 978-1-60332-261-4
Edited Components are Copyright (c) 2009 Equity Press
Smashwords Edition
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".
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Prenatal Development and Sonograph Images
Physiological Changes in Pregnancy
Dietary and Nutritional Factors
Cases of Pregnancy Over Age 50
Evolutionary Psychological Hypothesis
Effects on the Parent-Infant Relationship
References: Pregnancy over age 50
References: Postpartum Depression
GNU Free Documentation License
Pregnancy (latin graviditas) is the carrying of one or more offspring, known as a fetus or embryo, inside the uterus of a female. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets. Human pregnancy is the most studied of all mammalian pregnancies. Obstetrics is the surgical field that studies and cares for high risk pregnancy. Midwifery is the non-surgical field that cares for pregnancy and pregnant women.
Childbirth usually occurs about 38 weeks after fertilization (conception ), i.e., approximately 40 weeks from the last normal menstrual period (LNMP) in humans. The World Health Organisation defines normal term for delivery as between 37 weeks and 42 weeks. The calculation of this date involves the assumption of a regular 28-day period.
One scientific term for the state of pregnancy is gravid , and a pregnant female is sometimes referred to as a gravida .[1] Neither word is used in common speech. Similarly, the term "parity " (abbreviated as "para") is used for the number of previous successful live births. Medically, a woman who has never been pregnant is referred to as a "nulligravida ", and in subsequent pregnancies as "multigravida " or "multiparous ".[2][3][4] Hence during a second pregnancy a woman would be described as "gravida 2, para 1" and upon delivery as "gravida 2, para 2". Incomplete pregnancies of abortions, miscarriages or stillbirths account for parity values being less than the gravida number, whereas a multiple birth will increase the parity value. Women who have never carried a pregnancy achieving more than 20 weeks of gestation age are referred to as "nulliparous".[5] The medical term for a woman who is pregnant for the first time is primipara .[6]
The term embryo is used to describe the developing offspring during the first eight weeks following conception , and the term fetus is used from about two months of development until birth.[7][8]
In many societies' medical or legal definitions, human pregnancy is somewhat arbitrarily divided into three trimester periods, as a means to simplify reference to the different stages of prenatal development. The first trimester carries the highest risk of miscarriage (natural death of embryo or fetus ). During the second trimester, the development of the fetus can be more easily monitored and diagnosed. The beginning of the third trimester often approximates the point of viability, or the ability of the fetus to survive, with or without medical help, outside of the uterus.[9]
Pregnancy occurs as the result of the female gamete or oocyte being penetrated by 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 an egg. The fusion of male and female gametes usually occurs through the act of sexual intercourse. 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).
Prenatal or antenatal development is the process in which an embryo or fetus (or foetus) gestates during pregnancy, from fertilization until birth. Often, the terms fetal development , foetal development, or embryology are used in a similar sense.
After fertilization, the embryogenesis starts. In humans, when embryogenesis finishes, by the end of the 10th week of gestational age, the precursors of all the major organs of the body have been created. Therefore, the following period, the fetal period, is described both topically on one hand, i.e., by organ, and strictly chronologically on the other, by a list of major occurrences by weeks of gestational age.
Perinatal 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 500g) to seven completed days after birth. [10]
Legal regulations in different countries include gestation age beginning from 16 - 22 weeks (five months) before birth.
Postnatal (Latin for 'after birth', from post meaning "after" and natalis meaning "of birth") is the period beginning immediately after the birth of a child and extending for about six weeks. A more correct term would be postpartum period, as it refers to the mother (whereas postnatal refers to the infant). Less frequently used is puerperium.
Biologically, it is the time after birth, a time in which the mother's body, including hormone levels and uterus size, return to prepregnancy conditions. Lochia is post-partum vaginal discharge, containing blood, mucus, and placental tissue.
During the first stages of this period, the newborn also starts his/her adaptation to extrauterine life, the most significant physiological transition until death.
In scientific literature the term is commonly abbreviated to PX. So that 'day P5' should be read as 'the fifth day after birth'.
The expected date of delivery (EDD) is 40 weeks counting from the last menstrual period (LMP) and birth usually occurs between 37 and 42 weeks,[11] 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. 40 weeks is nine months and six days, which forms the basis of Naegele's rule for estimating date of delivery. More accurate and sophisticated algorithms take 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 pre-term; from week 42 (294 days) events are considered post-term.[12] When a pregnancy exceeds 42 weeks (294 days), the risk of complications for woman and fetus increases significantly.[11][13] As such, obstetricians usually prefer to induce labour, in an uncomplicated pregnancy, at some stage between 41 and 42 weeks.[14][15]
Recent medical literature prefers the terminology pre-term and post-term to premature and post-mature. Pre-term and post-term 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.[16][17]
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 two weeks.[18] It is much more useful, therefore, to consider a range of due dates, rather than one specific day. Some online due date calculators provide this information.
Accurate dating of pregnancy is important, because it is used in calculating the results of various prenatal tests (e.g. 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 advancing relentlessly as medical revolution continues to unfold. Whereas it used to be 28 weeks, this has been brought back to as much as 23 weeks [22 weeks in a few countries]. Unfortunately, there has been a profound increase in morbidity and mortality associated with the increased survival to the extent it has led some to question the ethics and morality of resuscitating at the edge of viability.
Childbirth is the process whereby an infant is born. It is considered by many to be the beginning of a person'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.
The beginning of pregnancy 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, which can signify pregnancy. The symptoms can include nausea and vomiting, excessive tiredness and fatigue, craving for certain foods not normally considered a favorite and frequent urination, particularly during night.
A number of early medical signs are associated with pregnancy.[19][20] 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 two 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).[19][20]
Pregnancy detection can be accomplished using one or more of various pregnancy tests which detect hormones generated by the newly-formed placenta. Clinical blood and urine tests can detect pregnancy soon after implantation, which is as early as 6-8 days after fertilization . Blood pregnancy tests are more accurate than urine tests.[21] Home pregnancy tests are personal urine tests, which normally cannot detect a pregnancy until at least 12-15 days after fertilization. Both clinical and home tests can only detect the state of pregnancy, and cannot detect the age of the embryo.
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 not even 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, or she has been charting her cycles, or the conception is as the result of some types of fertility treatment (such as IUI or IVF) the exact date of fertilization is unknown. Absent symptoms such as morning sickness, often the only visible sign of a pregnancy is an interruption of her 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 two 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.[22] The beginning of labour, which is variously called confinement or childbed, begins on the day predicted by LMP 3.6% of the time and on the day predicted by sonography 4.3% of the time.[23]
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.[1]
Pregnancy is typically broken into three periods, or trimesters , each of about three months. While there are no hard and fast rules, these distinctions are useful in describing the changes that take place over time.
Comparison of growth of the abdomen between 26 weeks and 40 weeks gestation.
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 or the cervix, causing an ectopic pregnancy . 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 is responsible for transport of nutrients and oxygen to, and removal of waste products from the fetus . 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 foetal development.
Morning sickness can occur in about seventy percent of all pregnant women and typically improves after the first trimester.[24]
In the first 12 weeks of pregnancy the nipples and areolas darken due to a temporary increase in hormones.[25]
Most miscarriages occur during this period.
Patient #1: Short cervix
I am 21 weeks pregnant with my first child, a little girl. My closed cervical length is at 2cm. I researched online and every where I read states the normal length at this time is around 4cm or 40mm. I am really nervous about this as I know it can lead to 2nd trimester miscarriage as well as preterm labor.
Patient #2: Weight and water retension issues
I lost a LOT of weight my first trimester, and half of the second…then I started having kidney and liver issues, severe water retension that resulted in sever joint stability issues.
Months 4-6 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 moving 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 20 to 21 week, or by the 19th week if the woman has been pregnant before. However, it is not uncommon for some women to not feel the fetus move until much later. The placenta is now fully functioning and the fetus is making insulin and urinating. The reproductive organs distinguish the fetus as male or female.
Patient #1: Possible undetectable TSH
My TSH (Thyroid Stimulating Hormone, aka thyrotropin) is undetectable and another thyroid test came back 17.5 with the high end of the normal reference range being 12.5.
My OB repeated the tests because she did not think my thyroid was high enough to justify an undetectable TSH, but the results came back the same.
She referred me to a maternal-fetal specialist who did not order anymore thyroid testing even though the fetal heart rate was 170. He ordered many other blood tests all of which came back normal.
Patient #2: Glucose Tolerance Testing (GTT)
I am still hyper to some degree five weeks into my second trimester- fevers, malaise, nausea, headache, and heart racing somedays. I'm thinking if it was only GTT, the hyper symptoms would have been completely gone by now, and my TSH would never have gotten that low.
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 28g 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 back-ache. 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.
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.[26] 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.
Patient #1: Contractions
I'll get contractions for a couple of hours at a time and they've been somewhat painful. I brought it up at my last doctor's visit and he checked me and said that I'm not dilating so they should be nothing to worry about. He said that sometimes with the second (or more) baby you sometimes get contractions like this. I'm only 33 weeks, so my boy better hold on in there!
Patient #2: Baby turning in womb
My doctor said there's not really anything to do about the baby turning- there are some exercises he gave me, but I've been doing them since 29 weeks and my baby still hasn't turned. She's just going to be stubborn, I guess. He said that at my 35 and 36 week appointments they would check me again and possibly do another ultrasound to see exactly where she's positioned, etc. And then they would talk to me about a manual version (since it's my second baby that's an option). I haven't done any research on it or decided whether I'd have it done if it comes to that...but it's an option that we will discuss in the next couple weeks. I'm 33 weeks 4 days and the weeks really seem to be flying by!
Patient #3: Baby movement in womb
I know that movement slows down quite a bit later in pregnancy... because there's less room in there. My baby still moves a lot, I don't think she knows exactly how big she is...it still hurts. I'm 34 weeks, but I remember with my first pregnancy I had a significant drop in movement right around 32-33 weeks, so much so that I called my doc and they got me in for an ultrasound...everything turned out ok, my first baby just went through her growth spurt a few weeks early and slowed down the movement earlier than most.
Prenatal Development and Sonograph Images
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,[27] all major structures including hands, feet, head, brain, and other organs are present, and they continue to grow and develop. When the fetal stage commences, a fetus is typically about 30mm (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.[28] Some fingerprint formation occurs from the beginning of the fetal stage.[29]
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 multiply at a rapid pace which continues until 3-4 months after birth. It isn't until week 23 that the fetus can survive, albeit with major medical support, outside of the womb. It is not until then that the fetus possesses a sustainable human brain. [30]
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.[35] Whilst 3D is popular with parents desiring a prenatal photograph as a keepsake,[36] both 2D and 3D are discouraged by the FDA for non-medical use,[37] but there are no definitive studies linking ultrasound to any adverse medical effects.[38] The following 3D ultrasound images were taken at different stages of pregnancy:
Physiological Changes in Pregnancy
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.
Prolactin levels increase due to maternal Pituitary gland enlargement by 50%. This mediates a change in the structure of the Mammary gland from ductal to lobular-alveolar. Parathyroid hormone is increased due to increases of calcium uptake in the gut and reabsorption by the kidney. Adrenal hormones such as cortisol and aldosterone also increase.
Placental lactogen is produced by the placenta and stimulates lipolysis and fatty acid metabolism by the woman, conserving blood glucose for use by the fetus . It also decreases maternal tissue sensitivity to insulin, resulting in gestational diabetes.
The body's posture changes as the pregnancy progresses. The pelvis tilts and the back arches to help keep balance. Poor posture occurs naturally from the stretching of the woman's abdominal muscles as the fetus grows. These muscles are less able to contract and keep the lower back in proper alignment. The pregnant woman has a different pattern of gait. The step lengthens as the pregnancy progresses, due to weight gain and changes in posture. On average, a woman's foot can grow by a half size or more during pregnancy. In addition, the increased body weight of pregnancy, fluid retention, and weight gain lowers the arches of the foot, further adding to the foot's length and width. The influences of increased hormones such as estrogen and relaxin initiate the remodeling of soft tissues, cartilage and ligaments. Certain skeletal joints such as the symphysis pubis and sacroiliac widen or have increased laxity.
One of the most noticeable alterations in pregnancy is the gain in weight. The enlarging uterus, the growing fetus , the placenta and liquor amnii, the acquisition of fat and water retention, all contribute to this increase in weight. The weight gain varies from person to person and can be anywhere from 5lb (2.3 kg) to over 100lb (45 kg). In America, the doctor-recommended weight gain range is 25lb (11 kg) to 35lb (16 kg), less if the woman is overweight, more (up to 40lb (18 kg)) if the woman is underweight.
Other physical changes during pregnancy include breasts increasing two cup sizes. Also areas of the body such as the forehead and cheeks (known as the 'mask of pregnancy') become darker due to the increase of melanin being produced.[39]
The female body experiences many changes as the fetus grows through each trimester as shown and discussed in this pregnancy video. Two women at different stages in their pregnancy illustrate what has happened to their bodies.
Blood volume increases by 40% in the first two trimesters . This is due to an increase in plasma volume through increased aldosterone. Progesterone may also interact with the aldosterone receptor, thus leading to increased levels. Red blood cell numbers increase due to increased erythropoietin levels.
Cardiac function is also modified, with increase heart rate and increased stroke volume. A decrease in vagal tone and increase in sympathetic tone is the cause. Blood volume increases act to increase stroke volume of the heart via Starling's law . After pregnancy, the change in stroke volume is not reversed. Cardiac output rises from four to seven litres in the 2nd trimester