Pregnancy and
Childbirth, terms for the gestation period of the human
reproductive cycle this is actually within 7-9 months of being heavy and
weakness striven to ensure reproduction occurs in a manner to which much pains
and worries and discarded.
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PREGNANCY
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Trimesters of Pregnancy
The typical human pregnancy lasts about
280 days (about 40 weeks) and is divided into trimesters, each lasting about 3
months. During pregnancy a woman’s body undergoes a variety of changes to
prepare for the growth, nourishment, and birth of a child. The health of the
developing fetus is closely tied to that of the mother. A pregnant woman who
consumes tobacco, alcohol, or certain drugs increases the risk that her baby
will be born prematurely or with birth defects.
Pregnancy starts when a
male’s sperm fertilizes a female’s ovum (egg), and the fertilized ovum implants
in the lining of the uterus. Because pregnancy changes a woman’s normal hormone
patterns, one of the first signs of pregnancy is a missed menstrual period Other
symptoms include breast tenderness and swelling, fatigue, nausea or sensitivity
to smells, increased frequency of urination, mood swings, and weight gain. Some
women also experience cravings for unusual substances such as ice, clay, or
cornstarch; this condition, called pica, can indicate a dietary deficiency in
iron or other nutrients. By the 12th week of pregnancy many of these symptoms
have subsided, but others appear. For example, a woman’s breasts usually
increase in size, and her nipples darken. The most obvious symptom is weight
gain; most physicians now recommend a gain of about 9 to 12 kg (about 22 to 26
lb) by the end of pregnancy.
The first few months of
pregnancy are the most critical for the developing infant, because during this
period the infant’s brain, arms, legs, and internal organs are formed. For this
reason a pregnant woman should be especially careful about taking any kind of
medication except on the advice of a physician who knows that she is pregnant.
X rays should also be avoided, and pregnant women should avoid smoking and
alcohol consumption.
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COMPLICATIONS
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Prenatal Testing
Two types of medical tests may be used
early in a woman’s pregnancy to determine if her fetus has a defective gene or
a chromosomal abnormality. Both procedures remove cells surrounding the
developing fetus. The cells obtained have the same genetic makeup as the fetus
and can be tested for genetic abnormalities. In chorionic villus sampling, a
doctor removes tissue from the chorionic villi, fingerlike projections that are
part of the developing placenta, between 10 and 12 weeks of pregnancy. Using
ultrasound guidance, the doctor inserts either a needle through the woman’s
abdominal wall or a thin, hollow tube called a catheter through her cervix to reach
the chorionic villi. The doctor suctions out cells using a syringe.
Amniocentesis is usually performed between 15 and 17 weeks of pregnancy. In
this procedure, a doctor uses ultrasound guidance to insert a needle through
the abdominal wall into the amniotic fluid surrounding the fetus. Cells from
the amniotic fluid are removed using a syringe. Both procedures pose a slight
risk for the developing fetus, and health professionals recommend these tests
only in cases in which a mother or father has a family history of a genetic
disorder or a known risk for chromosomal abnormalities.
Most women worry about
the health of their unborn child, especially mothers over the age of 35, when
genetic problems are more common. Safe, effective tests are available that can
detect genetic disorders which cause mental retardation and other problems. The
most common test is amniocentesis, and in about 95 percent of the cases tested
the baby is found to be normal. Some doctors recommend that all pregnant women
over the age of 35 have an amniocentesis test.
Amniocentesis
In amniocentesis, a medical procedure
generally performed during the fourth month of pregnancy, approximately one
ounce of the amniotic fluid surrounding the fetus is drawn off for study. The
examination of fetal cells contained in the sample can provide valuable
information about developmental abnormalities of the fetus.
Although most pregnancies
proceed normally, certain complications can develop. One rare but
life-threatening complication is ectopic pregnancy, in which the fertilized egg
implants outside the uterus, in the abdomen, or in a fallopian tube. Symptoms
include sudden, intense pain in the lower abdomen about the seventh or eight
week of pregnancy. If not promptly treated by surgical means, ectopic pregnancy
can result in massive internal bleeding and possibly death.
Ultrasound Image of Fetus
In this ultrasound image of a fetus in
the womb, the head of the fetus is partially outlined on the left side of the
picture. Ultrasound images are created when very high frequency sound is
reflected from living tissue and subsequently processed by a computer.
Ultrasound has a variety of medical applications, particularly in obstetrics,
where it is used during pregnancy to monitor fetal size and to identify
multiple pregnancies or structural abnormalities.
About 15 percent of all
pregnancies end in miscarriage, most of which occur between the 4th and 12th
weeks of pregnancy. A physician should be contacted immediately if a woman
suspects that she is pregnant and then experiences severe abdominal cramping or
vaginal bleeding.
Toxemia is another potentially
serious complication of late pregnancy. Symptoms include high blood pressure;
rapid, large weight gain, due to edema (swelling), of as much as 11 to 13 kg
(25 to 30 lb) in a month; and protein in the urine. If untreated, toxemia can
lead to seizures and coma and death of the infant. Once severe toxemia is
diagnosed, the infant is usually delivered as soon as possible to protect both
mother and child. The condition disappears with birth.
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LABOR AND CHILDBIRTH
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Stages of Labor
During childbirth, a woman undergoes a
process called labor, in which rhythmic contractions of the uterus expel the
baby through the vagina. Labor can be divided into six distinct stages,
although a laboring woman may not always be aware when one stage ends and
another begins.
A normal pregnancy lasts
about 40 weeks, or 280 days, after the beginning of the last menstrual period.
Occasionally women go into labor before the expected date of birth, resulting
in a premature infant. About 7 percent of all infants are premature—that is,
born before the 37th week of pregnancy. Babies born just a few weeks early
usually develop normally. Recent advances in the care of premature infants now
allow many babies who are born after only 25 to 26 weeks of pregnancy to
survive. Even babies born after only 23 weeks of pregnancy have survived,
although survival rates for such highly premature infants are low.
Childbirth
In the final stage of childbirth, the
umbilical cord is cut. The umbilical cord transports nutrition and oxygen from
the mother’s placenta to the fetus.
Delivery, the process by
which the baby is expelled from the uterus through the birth canal and into the
world, begins with irregular contractions of the uterus that occur every 20 to
30 minutes. As labor progresses, the contractions increase in frequency and
severity. The usual length of labor for a first-time mother is about 13 to 14
hours, and about 8 or 9 hours in a woman who has given birth previously. Wide
variations exist, however, in the duration of labor.
Birthing Pool
In the vast majority of hospital
births, doctors offer women some type of anesthesia to alleviate the pain of
uterine contractions during labor. Natural childbirth (birth without medication
or medical intervention) is becoming more popular in America and Europe, partly
because of women’s concerns that anesthesia used during childbirth may be
transferred to the unborn baby. This mother has just given birth in a birthing
pool. The warm water relaxes the mother’s muscles and provides some relief from
the pain of labor.
Most women prefer some
kind of anesthesia to alleviate the pain associated with childbirth. Natural
(unmedicated) childbirth, however, is becoming more popular, in part because
many women are aware and concerned that the anesthesia and medication given to
them is rapidly transported across the placenta to the unborn baby. Heavy doses
of anesthesia can make the newborn baby less alert after birth.
Other options available
regarding childbirth include regional (local) anesthesia, in which only those
areas of the mother that are affected by the pain of childbirth are numbed.
Such anesthesias include a lower spinal block and epidural anesthesia, in which
the pelvic region is anesthetized. Another option is cesarean section, in which
the baby is surgically removed from the uterus. Cesarean section is usually
performed only for a specific medical reason.
