Pregnancy

Pregnancy is the carrying of one or more offspring inside the uterus of a woman. The term embryo is used to describe the developing offspring during the initial weeks, and the term fetus is used from about two months of development until birth.

Pregnancy is divided into three trimester periods. 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 coincides with the fetus' ability to survive, with or without medical help, outside of the uterus.

A term pregnancy lasts 37-42 weeks. Preterm delivery occurs prior to 37 weeks gestation while a post-dates pregnancy lasts more than 42 weeks. The gestational age of the fetus is calculated starting from the first day of the last menstrual period. Although this date occurs prior to conception, it is the standard method of dating a pregnancy.

Obstetrics is the medical specialty that manages a woman's medical needs specifically related to pregnancy, delivery and the postpartum period.

Fertilization

Pregnancy begins after a sperm joins an egg to form an embryo. This is called fertilization. A woman usually releases one egg from her ovaries each month. Semen from a man usually contains several million sperm. During unprotected sexual intercourse, sperm make their way through the vagina and swim up the cervix and through the uterus to the fallopian tubes, where fertilization usually occurs. The sperm must break through outer layers of the egg in order to penetrate inside. Usually, only one sperm gets into the egg. Once inside, the DNA from the sperm and the egg combine to create a complete set of chromosomes. This new cell is an embryo.

Implantation

An embryo divides until it is composed of several cells that are identical copies of the original one. During this time, it moves from the fallopian tube into the uterus. The embryo secretes a hormone called human chorionic gonadotropin (HCG) that helps the embryo embed itself into the lining of the uterus, or endometrium. Meanwhile, the ovary secretes progesterone to help the pregnancy develop. During this time, the placenta and amniotic sac begin to grow. These help support the remainder of the pregnancy.

Gestation

The embryo continues to grow for eight weeks. During this time, the cells of the embryo begin to form different parts of the body. After eight weeks, the embryo is known as a fetus.

Fetus of about eight weeks, enclosed in the amnion. Source: Gray's Anatomy of the Human Body

Phases of Pregnancy

The phases of pregnancy are divided into trimesters. A normal pregnancy lasts anywhere between 37 and 42 weeks.

The first trimester (conception to 12 weeks) is the time of rapid growth and development. It is at this stage that the embryo or fetus is most sensitive to harm from chemicals such as drugs, alcohol, and many medications.

In the second trimester (13 to 28 weeks), the fetus continues to grow rapidly and begins to move.

Fetus in utero, between fifth and sixth months. Source: Gray's Anatomy of the Human Body

During the third trimester (29 weeks to birth), the fetus continues to grow, and develops recognizable physical features.

Labor and Delivery

Labor, or childbirth, has three stages.

First stage

The first stage of labor is divided into three phases: early, active, and transition. The phases are marked by how far the cervix, or opening of the uterus, has opened up or dilated.

• Early phase: Beginning of labor to dilation of the cervix to 3 cm
• Active phase: Cervical dilates from 3 to 7 cm
• Transition phase: Cervix dilates completely to 10cm

Second stage

This is the stage in which the baby is born. It begins when the cervix is completely dilated and continues as the mother pushes until the baby is born.

Third stage

During this stage, the placenta is delivered. This is augmented by holding and breastfeeding the baby, which increases oxytocin levels. Oxytocin stimulates the uterus to contract and helps the placenta to come out.

Types

An intrauterine pregnancy is the usual type of pregnancy, in which there is one fertilized egg implanted in the uterus.

A multigestational pregnancy occurs with multiple births such as twin pregnancies, triplet pregnancies, etc.

An ectopic pregnancy occurs when the fertilized egg implants outside of the uterus. Ectopic pregnancies rarely last to term, and can be very dangerous to the mother if the pregnancy outgrows its blood supply and ruptures.

How Pregnancy Occurs

Pregnancy occurs when one sperm fertilizes one egg. This can occur during sexual intercourse orwith assisted reproductive techniques such as artificial insemination (in which sperm is introduced artificially into the cervix) and in vitro fertilization (in which an egg is injected with a sperm outside of the body and then implanted into a woman's uterus to grow).

Signs and Symptoms

The primary sign of pregnancy is missing one or more consecutive menstrual periods. Other signs and symptoms of pregnancy may include the following:

• An intuitive sense by the woman that she is pregnant
• Nausea or vomiting, morning sickness
• Sore breasts or nipples
• Fatigue
• Headaches
• Food cravings or aversions
• Mood swings
• Frequent urination

During pregnancy, a woman will experience a variety of changes in her body:

• Weight gain is expected during pregnancy. Most women gain between 25 to 35 pounds. Some women need to gain more, and some need to gain less. Nutrition during pregnancy is critically important. It is important for mothers to eat nutrient-dense foods while pregnant to ensure their babies get the best nutrition possible.

• Urinary frequency is often due to a decreased ability of the bladder to hold as much urine. This typically occurs early in the pregnancy when the uterus first begins to expand, and is improved somewhat when the uterus grows enough to rise above the bony confines of the pelvis. At the end of the pregnancy when the uterus and baby are much larger, urinary frequency often returns.

Diagnosis

Pregnancy tests are the best way to detect a pregnancy. Home pregnancy test kits are available over-the-counter and are considered highly accurate. A health care provider can also do a pregnancy test.

The National Institute of Child Health and Human Development (NICHD) research in the 1970s found that high levels of the hormone human chorionic gonadatropin (HCG) in the urine were associated with pregnancy. This research led to the development of the home pregnancy test that is commercially available today.

Prenatal Care

Prenatal care is the care a woman gets during a pregnancy. Getting early and regular prenatal care is important for the health of both mother and the developing baby. According to the Centers for Disease Control and Prevention, 83.9% of women receive prenatal care in their first trimester.^[1] In addition, health care providers are now recommending that women see health care providers for preconception care before even trying to get pregnant in order to plan and prepare for any future pregnancies.

Below are some steps women can take to provide a healthy environment for the baby:

• Getting at least 400 micrograms of folic acid every day to help prevent many types of neural tube defects. Health care providers recommend taking folic acid both before and during pregnancy.
• Maintaining a nutritious diet and a healthy weight.
• Getting regular physical activity before, during, and after pregnancy.
• Avoiding smoking, alcohol, or drug use before, during, and after pregnancy.

Practitioners

For centuries, women have been pregnant and have not received special medical care. Midwives have provided care during pregnancy throughout history and remain the primary caregivers in many traditional societies. Today, many types of practitioners are available to help women maintain healthy pregnancies and to help those who are not healthy.

• Obstetricians are medical doctors who have special training in obstetrics and gynecology.
• Some family medicine physicians, specialists in the care of people of all ages, provide obstetric care. Generally family medicine physicians focus on the normal process of pregnancy and birth as a woman and family centered event, and are willing to work with women to provide medicated or natural births.
• Midwives continue to support women in pregnancy throughout the world. They practice with the point of view that pregnancy and childbirth are natural life processes rather than medical conditions. Many women who seek natural childbirth use midwives at home, birth centers, or hospitals.
• Doulas are women who accompany women during labor to assist in the birth and often also help women postpartum.

Childbirth Education

There are many types of childbirth education available. Two of the most popular childbirth preparation methods are Bradley and Lamaze.

High-risk Pregnancy

Factors present before pregnancy or that develop during pregnancy, can place the mother and baby at higher risk for problems. Women with high-risk pregnancies may need care from specialists or a team of health care providers to help promote healthy pregnancy and birth.

Factors present before pregnancy that can increase risk may include the following:

• Young or old maternal age
• Being overweight or underweight
• Having had problems in previous pregnancies, such as miscarriage, stillbirth, or preterm labor or birth
• Pre-existing health conditions, such as high blood pressure, diabetes, or HIV/AIDS

During pregnancy, problems may also develop even in a woman who was previously healthy. Examples include gestational diabetes, preeclampsia, and eclampsia.

Getting good prenatal care and seeing a health care provider regularly during pregnancy are important ways to promote a healthy pregnancy.

Statistics

According to the Centers For Disease Control and Prevention, in 2005, there were 2,873,918 births in the United States. Cesarean sections were performed in 30.3% of all deliveries.^[2]

Complications

Many complications of pregnancy can be detected and prevented. Some however, like spontaneous abortions, may go undetected.

Miscarriage

Miscarriage, also known as spontaneous abortion, is the loss of a pregnancy before the 20th week of pregnancy. Miscarriage occurs in as many as 10%-25% of all pregnancies.

Preeclampsia and eclampsia

Preeclampsia and eclampsia are serious conditions that can occur during pregnancy. Preeclampsia is characterized by high blood pressure and protein in the urine. Many care providers check the urine routinely during pregnancy to look for protein. Preeclampsia can progress to eclampsia which is characterized by preeclampsia plus seizures.

Premature labor

Preterm labor, or premature birth is labor that begins before the 37th week of pregnancy. Premature labor can often be stopped. If the baby is born early, he or she will probably need care in a neonatal intensive care unit. Babies born after the 32nd week of pregnancy usually do very well without long-term side effects.

Premature rupture of membranes

When the amniotic sac begins to leak fluid ("the water breaks") before the 37th week of pregnancy, this is known as premature rupture of membranes (PROM). This can happen for many reasons, including infections or anatomic problems with the sac or uterus. The mother may require treatment to avoid an infection of the membranes and to prevent preterm labor.

Related Disorders

Pregnancy can cause a variety of disorders in the mother. Some are transient and last only during the pregnancy, whereas others are long-term.

Morning sickness

Morning sickness occurs in most pregnant women. About one in four only has very mild nausea. Nausea is most common in the first trimester, and usually begins around the 8th to 10th week of pregnancy.

Gestational diabetes

Gestational diabetes occurs when the mother does not make enough insulin to handle the sugar in her bloodstream. This extra sugar gets passed on to the baby and can cause complications with the pregnancy. The most common of these is a high birth weight. Patients who have a previous history of diabetes have an increased risk of developing gestational diabetes during pregnancy. Providers will screen for gestational diabetes at the first visit and will continue to monitor throughout the pregnancy.

Back pain

Back pain is very common during pregnancy. Many women can find relief with a variety of postures and strengthening exercises.

Sciatica is another common complaint during pregnancy. This also usually improves with conservative measures such as exercise and positional changes.

Controversy

Many question the medicalization of childbirth. It is a natural process that has sustained the human species for thousands of years, but today most women have their children under the care of a physician. The field of obstetrics has certainly saved lives in cases of complicated pregnancies and difficult pregnancies. The controversy surrounds the fact that many women who could safely have natural childbirths do not.

Recent News

Talk show host Ricki Lake recently produced a documentary on childbirth in the United States titled The Business of Being Born. This film examines the current maternity system and asks "Should most births be viewed as a natural life process, or should every delivery be treated as a potentially catastrophic medical emergency?"

Videos

Lamaze International: Watch Women Give Birth With Confidence

The video below show the development of a fetus.

The video below shows a ultrasound of a fetus at the age of 27 weeks.

For a menu of YouTube videos related to home birth, midwifery, and health issues in general, visit www.themidwife.net.

References

1. ↑ Centers for Disease Control and Prevention. Prenatal Care.
2. ↑ Martin JA and colleagues. Births: Final Data for 2005. National Vital Statistics Reports. CDC. Volume 56, Number 6.

External Links

• Video of a Cesarean Section

American College of Obstetricians and Gynecologists:

American College of Nurse Midwives

Doulas of North America

American Academy of Family Physicians

The National Women's Health Information Center

March of Dimes

American Pregnancy Association

International Childbirth Education Association

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