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Definition: pregnancy from Philip's Encyclopedia

Period of time from conception until birth, in humans normally c.40 weeks (280 days). It is generally divided into three 3-month periods called trimesters. In the first trimester, the embryo grows from a small ball of cells to a fetus c.7.6cm (3in) in length. At the beginning of the second trimester, movements are first felt and the fetus grows to about 36cm (14in). In the third trimester, the fetus attains its full body weight. See also labour

Summary Article: Pregnancy
From Encyclopedia of Motherhood

Still somewhat a subject of mystery, pregnancy holds a particularly important place within cultures and women's lives, as evidenced by the multitude of religious, scientific, cultural, and social beliefs about its definition, its role in society, and women's bodies. Responses are mixed as to whether pregnancy signals a woman's move into the role of “mother,” since not all women who are pregnant carry the fetus to term or keep the child after birth. Some women who are mothers are never pregnant, and some women consider themselves mothers even if they do not have children. Regardless of context, pregnancy remains central to women's lives—even if they never are or intend to become pregnant—and important to cultural beliefs and study.

Historical Background

People have developed theories and speculated on pregnancy for millennia, and continue to do so. Research into birth control indicates humans have known for centuries, if not specifically, that sexual intercourse between a man and a woman could lead to pregnancy. Cultures continue to propagate beliefs about how or when pregnancy can occur, including that virgin females cannot become pregnant when having sex the first time, women control the gender, and features of the child are based upon the women's dreams or what they see when having sex, and women can only become pregnant after midnight and before 5:00 a.m. These and other beliefs remain central to many peoples’ ideologies regarding pregnancy. Since the early 20th century, medical science has continued to alter its understanding of pregnancy. The knowledge of the importance of sanitation during delivery has done a great deal to significantly lower the maternal mortality rate across the globe, even as many midwives in the late 19th and early 20th century, for which records are maintained, had better rates than most of their medical professional peers.

Core Definition

Pregnancy occurs when a fertilized egg—a zygote—implants itself in a woman's uterus. Implantation remains at the core of this definition. During their own gestational period, a female fetus develop her lifetime supply of eggs, and this number, by some calculations nearing 7 million, begins to drop off to about 1 million when the baby is born. Around 12 years of age, girls begin their first menstrual cycle, during which the ovary releases an egg about every 28 days. If the egg receives a sperm, pregnancy may occur. If the egg is not fertilized, the developing endometrium, or uterine lining, is shed through the vagina and urethra, known as menstruation. If uninterrupted by birth control methods after menarche, a woman's ovaries will continue to release these developed eggs throughout her lifetime until menopause, when the ovary no longer has eggs to release.

Fertilization most often occurs through vaginal intercourse between a woman and a man. Biologically, fertilization may lead to pregnancy through a complex process. Women and men may also prevent pregnancy through a variety of physical, pharmaceutical, and herbal means. If no birth control methods are used—and sometimes regardless of these methods—and intercourse occurs around 48 hours before or after the ovary releases an egg, individual sperm that travel through the vagina, uterus, and uterine tube can meet the egg and fertilize it. Propelled both by the tail and follicles and minor contractions in the uterine tube, the sperm meet the egg, but the egg only accepts one. If fertilization occurs, the zygote moves through the uterine tube into the uterus, where it implants itself in the uterine wall and remains for approximately

38 weeks (40 weeks if the length is determined by last menstrual cycle), the length of a full-term pregnancy. If the zygote does not move to the uterus and implants elsewhere in the woman's abdominal area, it becomes known as an ectopic pregnancy, a potentially dangerous condition for the woman. The zygote must be removed, usually through medical intervention, as it is unlikely the zygote will mature. Depending on how mature the zygote has become, this situation can result in irreversible damage to the woman's body and possibly her death.

Pregnancy can be detected by the woman sometimes days after fertilization, based upon sensitivity in the breasts, increased exhaustion, or dreams that signify children or birth. Over-the-counter pregnancy urine tests and medical blood tests verify pregnancy by measuring human chorionic gonadotropin (hCG), which is produced during pregnancy. In the absence of these tests, a woman will most likely be able to confirm the pregnancy when she misses her upcoming menstrual cycle, as hormones released during pregnancy prevent the ovaries from releasing additional eggs until the pregnancy ends. Likewise, it appears that hormones released once an egg is fertilized prevent the body's immune system from treating the zygote and, later, the fetus, as a foreign body. These hormones decrease as the pregnancy reaches its end, and the levels return to pre-pregnancy rates following the pregnancy's end.

Assisted Reproductive Technology

Fertilization may also occur through assisted reproductive technology (ART), which includes in-vitro fertilization (IVF), whereby a medical professional fertilizes an egg in a laboratory setting and implants the fertilized egg into the woman's uterus. In-utero insemination (IUI), a medical professional injects semen directly into a woman's uterus. The eggs used for IVF require an egg donor, who begins a drug regimen that induces her ovaries to release multiple eggs. Medical professionals then extract multiple eggs at once. The egg does not need to be produced by the woman who is receiving the zygote(s), which implant in the wall of the uterus once injected, beginning the pregnancy. Some women act in the capacity of a surrogate, and after delivery, gives the child to the person/people for whom she was carrying the fetus.

Men who are sperm donors ejaculate semen into receptacles, which are sometimes cryogenically maintained for later use. Because of the low success rate of IVF (12-15 percent), professionals often fertilize many eggs in case one does not implant properly in a woman's uterus.

These remaining noninjected but fertilized eggs have caused a round of debates in terms of their role and purpose. According to medical and cultural definitions, these fertilized eggs remain in some unknown space not defined as pregnancy, since the zygotes have not implanted themselves in a woman's uterus, the medical definition of pregnancy. Some argue the fertilized eggs can and must be discarded after a designated period of time; others contend they should be used for research into human development and stem cells; and others argue they are human beings who must be protected.

Women are more likely to become pregnant with multiples using IVF procedures than they are with vaginal intercourse, thus often leading to continued medical monitoring and intervention during the pregnancy, particularly during birth. Debate surrounds IVF and ART, with arguments running the extremes and moderations of many voices. For many families and single women, IVF permits the desire of child rearing to become a reality.

End of Gestational Period

Pregnancy may end in a variety of ways, including full-term birth of a live child, premature birth, miscarriage, stillborn, and abortion. Full-term live births generally occur when the uterus begins to contract, often after 38 weeks of gestation, and the uterus moves the fetus through the vagina or medical professionals remove the fetus through caesarean section. Vaginal delivery may be initiated through release of hormones or depletion of particular hormones in the woman's body, through oxytocin injections or suppositories, or by physical or mental trauma to the woman. Stillborn fetuses cease functioning while still in the uterus, often near the end of the gestational period, and they may be removed either through medical intervention or when the uterus begins to contract as with a full-term live birth.

Although miscarriage occurs for multiple reasons, the most likely being chromosomal abnormality, it is most likely to occur during the first three months of a pregnancy The true miscarriage rate is unknown, because many miscarriages occur before the woman knows she is pregnant. A common estimate is 40-50 percent of all pregnancies; one study that tracked chemical changes in the mother's body found a 31 percent rate, but considered that to be an underestimate because the method could not detect a fetus in the first few days after conception.

Abortion, while a socially and politically sensitive topic, happens through medical and individual intervention, removing the fetus before it can survive on its own outside the woman's uterus. Premature birth, like miscarriage, occurs for many reasons, some unknown. Some known factors are chromosomal abnormalities in the fetus; environmental toxins; the mother smoking, drinking alcohol, or taking drugs during pregnancy; and domestic violence enacted upon pregnant women. Although some premature children do not survive infancy due to underdeveloped systems, other premature children, often only with medical intervention, develop fully.

In the Western medical community, pregnancy is divided into three trimesters, and the first has been determined to carry the highest risk for a miscarriage. These trimesters do not necessarily coincide with specific developments of the fetus or changes to the woman's body, but rather reflect the symmetrical breakup of the general nine-month period of a pregnancy. Some cultural groups sometimes do not divide pregnancy into any specific periods, and other groups may organize pregnancy around each month, noting developments and issues the woman may want to consider. Knowledge about fetal development includes genetics, age of the woman and man, time of day conception occurred, thoughts the woman has, and the physical environment that surrounds the woman.

Changes to the Body

Nonmedical and medical communities alike devote significant support, study, and advice about pregnancy and to pregnant women. Many groups support or acknowledge the alterations the woman's body undergoes during pregnancy, which may include sensitivity and size of breasts, changes to pigmentation on the face and stomach, increased pressures on the cardiovascular and gastrointestinal systems, frequency of nausea, food cravings or aversions, and feelings of peace or calm. As the uterus grows in size throughout the pregnancy, it requires additional space from some of the woman's organs, including the bladder, leading to frequent urination near the end of the pregnancy. The breasts continue to grow in size, sometimes not returning to their original size as the uterus does following the pregnancy's end, and the mammary ducts begin to produce colostrum in preparation for breastfeeding.

A few days before contractions begin, many women report what has been termed “the nesting impulse.” During this phase, many women act upon a need to put the home space in order, preparing for the arrival of the child. Most cultures support moderate exercise, healthy eating, and sexual activity of pregnant women, but many also encourage pregnant women to sequester themselves from certain activities and environmental conditions, such as loud noise, toxic fumes, rigorous physical activity near the end of the pregnancy, sexual activity, or overeating or dieting.

Health Requirements

Prenatal care remains important to pregnant women to ensure their health and the health of the fetus, but levels and standards of care vary across continents. The World Health Organization has recommended a trained medical staff person to be present at all births to decrease the current annual maternal mortality rate (over half a million), but levels of care up to birth are dependent upon sociocultural beliefs and knowledge, geography, socioeconomic level, and pregnant women themselves. Attendance by trained birthing professionals, whether medical professionals, midwives, or doulas, has also limited the cases of obstetric fistula across the globe.

Although common in some developing nations, obstetric fistula occurs through a variety of causes, including previous medical or physical trauma to the reproductive organs, sexual abuse, cancer, and female genital cutting. Traumatic vaginal delivery remains the most typical cause, when the fetus puts significant and/or prolonged pressure on the vaginal wall. This pressure leads to a tear either between the vagina and the rectum or the vagina and the bladder. If left untreated, obstetric fistula causes the woman a lifetime of severe pain, intestinal leaking, infections, and possibly death.

Prenatal care includes providing women with information about the changes in their own bodies—both physical and emotional—and in the fetus, the impact of exercise and nutrition, results of weight and abdominal growth, and safety of the woman within the home. Physical and mental abuse of pregnant women remains a problem in communities around the globe.

It is well known that many women do not receive adequate nutrition when they are not pregnant, and, if continued during pregnancy, has adverse effects on the woman's body, the fetus, and the woman's ability to produce breastmilk. Nutrition levels remain associated with socioeconomic levels, cultural valuation or devaluation of women, and access to trained health workers. Researchers note that when factors limiting nutrition are present, there is an increase in mortality rates of the pregnant woman and the fetus or child. Many women in India suffer from physical and mental weakness that tends to impact them during their childbearing years, regardless of whether or not they have undergone medical sterilization; this weakness can be traced back to poverty, lack of proper nutrition, high levels of work within and outside of the home, frequent pregnancies, and cultural constructions of gender that devalue females.

Recent information gathered from developed nations suggests that pregnant women in the United States, specifically, may engage in too little exercise and consume too much high-calorie food when pregnant, leading medical and governmental health communities to encourage these pregnant women to exercise more and eat less during their pregnancies. Health concerns related to high weight gain during pregnancy include diabetes and high blood pressure for the woman and increased birth weight of the fetus, which may lead to caesarean section rather than vaginal delivery and future health concerns for the child.

The Pregnant Body

Often held in high public regard, the pregnant body exists as a site for important and sometimes contentious public discussion, as many women who are or have been pregnant can confirm through narratives of strangers offering blessings, physical touching of the pregnant abdomen, or advice about the pregnancy. A common belief persists that women remain ultimately responsible for the life of the fetus and the outcome of the child. Little research, has been conducted on the production of sperm or overall health of sperm in terms of men's responsibility and impact upon pregnancy. Many tend to note that because only “normal” sperm reach the egg, these sperm must be healthy and, with the exception of genetic contributions, cannot have negative impact on the fetus. When pregnant, a woman may feel that members of the community observe the woman's actions both to protect her and prevent her from participating in activities, eating food, or being in environments that may adversely impact the fetus. This increased surveillance—real or imagined—may place additional stress upon the woman during her pregnancy.

Some believe that pregnant women occupy a “condition” that limits their ability to function normally in the society. Whether these women represent fertility or vulnerability, they often do experience periods of increased fatigue and imbalance, simply due to the physical alterations of their bodies. Beliefs remain varied about pregnant women and physical activity, ranging from ideas that women who are physically strong and active before and during pregnancy will have an easier birth labor and recovery time than women who are not active, to beliefs that pregnant women must take additional rest or not lift heavy objects.

Recent medical discussions surround the connections between the pregnant woman's body and complications during birth; birth defects; and consumption of alcohol, drugs, and tobacco by pregnant women. Medical research, although in some cases with conflicting or incomplete information, discourages pregnant women from consuming alcohol, smoking tobacco, taking illegal drugs, or taking various prescribed and over-the-counter medications while pregnant. These substances have been found in some cases to have negative impacts on the fetus, including low birth weight, physical abnormalities, and learning disabilities. Further research continues to be conducted in this area, including the impact of environmental toxins such as pollution, carcinogens in fabric and household items, and industrial products on the fetus. Women certainly have some control over the ingestion or use of certain products, but they have little choice if their living environment contains these products.

Extraordinary conditions of the fetus or child is often attributed to the woman's intentions or environment. Medical research has clearly dispelled any connection between the woman's intentions or environment with respect to Rh level, ectopic pregnancy, or preeclampsia, a condition marked by swelling of the extremities near the end of the pregnancy. Additionally, while both sets of parental chromosomes impact genetic birth defects, syndromes such as Down's have connections to chromosomal abnormalities within the zygote and fetus, but have no connection to the parental chromosomes or woman's actions.

A Mother's Experience of Pregnancy

For most women in the industrialized world, pregnancy usually involves repeated checkups with a doctor who specializes in pregnancy and childbirth, and procedures such as ultrasound to track the baby's growth and health. The birth will probably take place in a hospital where the highest levels of emergency care are available, but where a woman may also feel that her experience has become subject to control by a highly technological medical establishment. To make the pregnancy and birth more personal and retain more control of the process, a mother may hire a professional doula or midwife to assist with prenatal care, the birth, and to care for the baby in the first days. If the birth is uncomplicated and the baby is healthy, a mother will be discharged within a few days. Giving birth at home (usually with the aid of a midwife or other professional) is increasingly popular as well. New mothers often feel isolated and overwhelmed if female relatives, friends, or a doula are not available to help her adjust.

In developing countries, a woman may receive very little prenatal care, and many women give birth at home. If any skilled care is available, it often comes from a midwife or community member (usually female) trained to assist in birth. The experience of birth is often communal, with many female relatives and neighbors assisting in the preparations, birth, and care of the mother and child after birth. This experience lacks the incongruity many women experience from giving birth in a hospital, but offers less help to mother and infant should a medical emergency arise.

See Also:

Abortion, Artificial Insemination, Birth Control, Birth Imagery, Metaphor, and Myth, Birth Mothers, Body Image, Breastfeeding, Breastmilk, Childbirth, Doula, Ectogenesis, Fertility, Home Births, Maternal Body, Maternal Health, Midwifery, Miscarriage, Mommy Brain, Obesity and Motherhood, Obstetrics and Gynecology, Postpartum Depression, Prenatal Health Care, Reproduction, Stillbirth

  • Boston Women's Health Collective. Our Bodies, Ourselves: Pregnancy and Birth. Clearwater, FL: Touchstone, 2008.
  • Costa, Shu. Lotus Seeds and Lucky Stars: Asian Myths and Traditions About Pregnancy and Birthing. New York: Simon & Schuster, 1998.
  • Medline Plus. “Miscarriage.” (accessed August 2009).
  • Ngoc, Nhu; Nguyen, Thi “Causes of Stillbirths and Early Neonatal Deaths: Data From 7993 Pregnancies in Six Developing Countries.” Bulletin of the World Health Organization, v.84 : , .
  • Obermeyer, Carla Makhlouf ed. Cultural Perspectives on Reproductive Health. Oxford, UK: Oxford University Press, 2001.
  • Piñón, Ramón Jr. Biology of Human Reproduction. Sausalito, CA: University Science Books, 2002.
  • Saul, Stephanie “Grievous Choice on Risky Path to Parenthood.” New York Times : , October 11, 2009 (accessed October 2009).
  • Jones, Rita M.
    Lehigh University
    Copyright © 2010 by SAGE Publications, Inc.

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