[L. praegnans, with child, pregnant]
The condition of having a developing embryo or fetus in the body after successful conception. The average duration of pregnancy is about 280 days. Estimation of the date on which delivery should occur is based on the first day of the last menstrual period. SEE: Naegeli rule; SEE TABLE: Pregnancy Table for Expected Date of Delivery; SEE: prenatal care; SEE: prenatal diagnosis
About 7 million American women become pregnant each year, and about two thirds of these pregnancies result in live births. In 2009, there were 4,143,000 live births in the U.S.
SYMPTOMS AND SIGNS
Presumptive and probable signs are those commonly associated with pregnancy but may be due to other causes, such as oral contraceptive therapy. Presumptive symptoms include amenorrhea, nausea and vomiting, breast tenderness, urinary frequency, fatigue, chloasma, vaginal hyperemia (Chadwick sign), and “quickening.” Probable signs include increased abdominal girth, palpable fetal outline, softening of the lower uterine segment (Hegar sign), softening of the cervix (Goodell sign), and immunodiagnostic pregnancy tests. Positive signs and symptoms of pregnancy are auscultation of fetal heart sounds, fetal movements felt by the examiner, and an identifiable embryonic outline on ultrasound.
The pregnant woman experiences many physiological alterations related to the increased levels of estrogen and progesterone and to the demands of the growing fetus; every system in the woman's body responds to these changes.
Reproductive tract changes: Alterations in uterine size, shape, and consistency include an increase in uterine muscle mass over the months of pregnancy. In response to elevated estrogen and progesterone levels, the cervix and lower uterine segment soften. A thick mucous plug fills the cervical canal. Vaginal secretions increase, and vaginal pH is more acidic (pH = 3.5 to 6.0). Change in vaginal pH discourages the survival and multiplication of bacteria; however, it also encourages infection by Candida albicans. The vagina elongates as the uterus rises in the pelvis; the mucosa thickens, with increases in secretions, vascularity, and elasticity.
SEE: Chadwick sign; SEE: Goodell sign; SEE: Hegar sign
Breast changes: The breasts become enlarged, tender, and more nodular. The areolae darken; the nipples become more sensitive and erectile; and Montgomery's tubercles enlarge. Colostrum may leak out during the last trimester, as the breasts prepare for lactation.
Endocrine glands: The size and activity of the thyroid gland increase markedly. Levels of thyroid-binding globulin and triiodothyronine rise; levels of thyroid-stimulating hormone drop slightly. These changes allow the pregnant woman to meet the endocrine needs imposed by the developing fetus, and other body changes that occur during pregnancy. Pituitary activity increases; prolactin levels increase ensuring lactation; placental hormones prevent ovulation and encourage development of the corpus luteum. Parathyroid activity decreases during the first trimester, then increases throughout the pregnancy to meet the increasing calcium demands of the fetus. Insulin resistance increases; this poses a risk, for some women, of glucose intolerance or gestational diabetes mellitus.
Cardiovascular alterations: Circulating blood volume increases progressively throughout pregnancy, peaking in the middle of the third trimester. Although the red blood cell count rises by about 30%, a 50% increase in blood volume creates dilutional anemia. The lower relative hematocrit decreases the viscosity of the blood. However, a hemoglobin concentration of less than 11 g is usually due to iron deficiency. Rising levels of clotting factors VII, VIII, IX, X, fibrinogen, and von Willebrand factor increase coagulability. The pulse rate increases, along with cardiac stroke volume. Peripheral vascular resistance drops. Mid-trimester blood pressure may be slightly lower than normal but remains essentially unchanged.
Skeletal system: Softening and increased mobility of the pelvic articulations is reflected in the waddling gait of pregnancy. As pregnancy progresses, the woman's center of gravity shifts, and the lumbar curve increases to compensate for the growing anterior weight of the gravid uterus. Problems with dental caries may become more prominent during pregnancy but can be prevented with oral rinses (such as chlorhexidine) and regular brushing and flossing.
Respiratory system: The effects of progesterone on smooth muscle include a decreased airway resistance, which enables the woman to meet her increased needs for oxygen by permitting a 30% to 40% increase in tidal volume and a 15% to 20% rise in oxygen consumption. The effects of estrogen include edema and congestion of the nasal mucosa, reflected in nosebleeds and nasal stuffiness.
Gastrointestinal system: Nausea and vomiting are the most common complaints during the first trimester. Progesterone-related diminished motility contributes to common complaints of heartburn and constipation. Hemorrhoids are common, caused by increased pressure in the lower pelvis and constipation.
Immune system: Alterations in T helper cell dominance produce immunological tolerance for the fetus and the placenta, both of which contain antigens that are alien to the mother. During pregnancy, autoimmune diseases such as rheumatoid arthritis or systemic lupus erythematosus tend to become less active.
Skin: Pigmentation changes in pregnancy include chloasma (the mask of pregnancy), areolar darkening, and linea nigra (a pigmented line that vertically bisects the abdomen). They reflect estrogen-related stimulation of skin melanocytes. Striae gravidarum, stretch marks, may appear in the skin of the abdomen, breasts, and thighs.
Urinary system: By the middle of the first trimester, the glomerular filtration rate has risen by about 50%; in compensation, tubular reabsorption also increases. Although urinary frequency is common in the first and last trimesters, bladder capacity actually increases; however, pressure from the growing uterus reduces the volume required to stimulate voiding. During the second trimester, the uterus rises out of the pelvis, becoming an abdominal organ and relieving bladder compression until late in the third trimester.
Weight: In average-sized women, the expected first-trimester weight gain is 2 to 5 lb. Total weight gain and the pattern by which it increases should be monitored to enable early signs of pregnancy-related problems common to the particular point in gestation. The Institute of Medicine recommends the following weight gains during singleton pregnancies: a woman with a prepregnancy body mass index less than 19.8 should gain 25 to 39 lb (11.4 to 17.7 kg); a woman with a prepregnancy body mass index from 19.8 to 26 should gain 25 to 34 lb (11.4 to 15.5 kg); and a woman with a prepregnancy body mass index from 26 to 29 should gain 15 to 24 lb (6.8 to 10.9 kg). The recommended weight gains during pregnancy are different for multiple gestations, e.g., a woman carrying triplets should gain about 50 lb (22.7 kg) during her pregnancy.
A pregnancy test, either urine or blood sample is taken, determines whether a woman is pregnant. Markers that indicate pregnancy, e.g., human chorionic gonadotropin (hCG), are found in the blood and urine.
An essential component to anticipatory guidance and patient teaching is to encourage the woman's active participation in her own health maintenance and pregnancy progress. Health care providers describe to pregnant women common complaints related to normal physiological changes of pregnancy and suggest actions to minimize discomfort.
Nausea and vomiting.
SEE: morning sickness
Heartburn: Hormone-related delayed gastric emptying, cardiac sphincter relaxation, and stomach displacement by the growing uterus contribute to reflux. The use of low-sodium or combination aluminum hydroxide/magnesium hydroxide preparations is recommended for symptomatic relief. For severe, unresponsive heartburn, over-the-counter H2-recedptor antagonists, such as ranitidine (Zantac) or famotidine (Pepcid), may be recommended.
Constipation: The woman should increase fiber and fluid intake. She also may use stool softeners.
Muscle cramps: The woman may relieve the so-called charley horse that occurs during sleep by dorsiflexing the foot of the affected leg. A calcium-phosphorus imbalance may contribute to increased frequency of this problem, although the causes are not clear. The woman can increase calcium intake by drinking the recommended daily quart of milk or by drinking a pint of milk daily and taking a calcium supplement with vitamin D.
Back pain: Growing anterior mass, shift in center of gravity, and increased lumbar curve contribute to backaches. To relieve discomfort, the pregnant woman should wear well-fitting, low-heeled shoes and perform exercises that increase abdominal muscle tone.
SEE: pelvic rock; SEE: pelvic tilt
Dependent edema: Pedal edema is a common third-trimester complaint related to decreased venous return from the extremities. The woman is advised to rest frequently and to elevate her feet. She should report promptly any edema of the face, hands, or sacral area to facilitate early diagnosis and management of pregnancy-induced hypertension.
Varicose veins: Decreased venous return from the extremities and compression of vascular structures by the growing uterus aggravate any weakness in the vascular walls and valves. Varicosities often occur in the legs, vulva, and pelvis. The woman should avoid tight clothing and prolonged standing. Other preventive and therapeutic measures include wearing support stockings, resting in left Sim position, and elevating the lower limbs during sleep.
Hemorrhoids: Temporary symptomatic relief may be obtained by Sitz baths and analgesic ointments. The woman also should be instructed in how to reinsert the hemorrhoid with a well-lubricated finger, holding it in place for 1 to 2 min before releasing the pressure.
Vaginal discharge: A normal increase in vaginal discharge occurs during pregnancy. Common perineal hygiene usually is effective as a comfort measure; douching is contraindicated during pregnancy. The woman should contact her primary caregiver promptly if profuse, malodorous, or blood-tinged discharge occurs.
Dyspnea: Shortness of breath occurs as the growing uterus presses on the woman's diaphragm. Elevation of the head and shoulders may provide some relief. The dyspnea disappears when lightening occurs.
Pruritus: The normal stretching of the skin may generate itching on the breasts, abdomen, and vulva. Pruritic urticarial papules and plaques of pregnancy is the most common benign dermatosis of pregnancy. Occurring in the third trimester, it usually resolves spontaneously after delivery. If severe, topical emollients, steroids, and antihistamines may provide some relief. Use of an emollient lotion may be suggested; the patient is instructed to inform her primary caregiver if vulvovaginal itching occurs in conjunction with an increase or alteration in vaginal discharge.
A woman's nutritional status before and during pregnancy is an important factor that affects both her health and that of her unborn child. Nutritional assessment is an essential part of antepartal care. In addition, the presence of preexisting and coexisting disorders, such as anemia, diabetes mellitus, chronic renal disease, and phenylketonuria, may affect dietary recommendations. Substance abuse increases the risk of inadequate nutrition, low maternal weight gain, low-birth-weight infants, and perinatal mortality.
Dietary recommendations emphasize a high-quality, well-balanced diet. Increased amounts of essential nutrients, i.e., protein, calcium, magnesium, zinc, and selenium, B vitamins, vitamin C, folate, and iron, are necessary to meet nutritional needs of both mother and fetus. Most nutritional and metabolic needs can be met by eating a balanced daily diet containing approx. 35 kcal for each kilogram of optimal body weight plus an additional 300 kcal/day during the second and third trimesters. Because it is difficult to meet all the daily dietary recommendations, vitamin and iron supplements are recommended.
Travel: Preparing for travel during pregnancy will depend upon the number of weeks' gestation, the duration of the travel, and the method, i.e., auto, boat, bus, train, airplane.
Safety belts, preferably the combined lap and shoulder type, should be worn with the lap portion below the pregnant abdomen not across it. If nausea and vomiting of pregnancy is a factor, travel by sea isn't advisable. If anti-motion-sickness medication is used, it should be one approved for use during pregnancy (or antinausea wrist bands may be used). Travel during the last part of pregnancy is not advised unless obstetrical care is available at the destination(s). It is important to carry a copy of current medical records when traveling. Travel abroad should be discussed with the obstetrician so that appropriate immunizations can be given. For travel in an area known to be endemic for malaria, certain drugs will be needed for prophylaxis.
Live virus immunization should not be administered during pregnancy.
Working: Healthy pregnant women who are employed in jobs that present no more risk than those in daily life are encouraged to continue working if they desire until shortly before delivery.
Exercise: If the pregnancy is progressing normally, exercise should be continued. The amount and type of exercise is an individual matter. A woman who has exercised regularly before her pregnancy should experience no difficulty with continuing; however, a previously sedentary woman should not attempt to institute a vigorous exercise program such as long-distance running or jogging during her pregnancy. No matter what the type of exercise, it is important to remember that, with the progress of pregnancy, the center of gravity will change and probably prevent participation at the same level and skill as before pregnancy. Sports to avoid include water skiing, horseback riding, and scuba diving. In horseback riding, in addition to the possibility of falling from the horse, the repeated bouncing may lead to bruising of the perianal area. Scuba diving may lead to decompression sickness and bends and to intravascular air embolism in the fetus. Women who breast-feed their children should continue exercising if they maintain hydration and adequate breast support.
Sexual intercourse: Women who are experiencing normally progressing pregnancies need not avoid intercourse. Pregnant women should refrain from coitus if they have a history of preterm labor or premature rupture of membranes and if they are bleeding or have ruptured membranes.
Tests: Common tests include blood tests for nutritional or sickle cell anemia, blood type and Rh factor, rubella titers, syphilis, and serum alpha-fetoprotein for the presence of neural tube defects such as spina bifida. Additional testing may include determining HIV status and hepatitis immunity. Ultrasound may be used to determine age, rate of growth, position, some birth defects, and fetal sex. Chorionic villus sampling may be done early in pregnancy if the family history indicates potential for genetic diseases. Second trimester amniocentesis may be used to detect chromosomal abnormalities, genetic disorders, and fetal sex. In late pregnancy, nonstress tests, contraction stress tests, and fetal biophysical profiles may be done; amniocentesis may be done to evaluate fetal lung maturity. SEE TABLE: Recommended Screening for Pregnant Women
Vaccinations: Influenza vaccination is recommended during pregnancy
Pregnancy in adolescence: Although pregnancy among teenagers is decreasing in the U.S., approx. 7% of all American teenage girls still become pregnant in any given year, one of the highest rates of teenage pregnancy in developed countries. Sociocultural factors are believed to contribute to the high incidence of pregnancies among this population. Demographic data indicate that teenage pregnancy is more likely to be associated with being single, having low socioeconomic status, and lacking social support systems. Pregnant teenagers are believed to be at high risk for some complications of pregnancy; if, however, they seek prenatal care early and consistently cooperate with recommendations, the risk is comparable to that for other age groups. Clinical data identify a common pattern of late entry to the prenatal care system, failure to return for scheduled appointments, and noncompliance with medical and nursing recommendations. As a result of these behaviors, adolescents are at higher risk for pregnancy-related complications, such as iron-deficiency anemia, pregnancy-induced hypertension, preterm labor and delivery, low birthweight newborns, and cephalopelvic disproportion. Other health problems seen more commonly in pregnant adolescents include sexually transmitted diseases and substance abuse.
SEE: high-risk pregnancy
Mature pregnancy: A growing number of women are experiencing their first pregnancies after age 35. The incidence of fetal demise among this population is 6:1000 births, double the rate for women under 35. Many factors may contribute to the increased risk, including preexisting and coexisting conditions, such as diabetes mellitus, hypertension, and uterine fibroids. Mature women are identified as being at higher risk for spontaneous abortion, preeclampsia, abruptio placentae, placenta previa, gestational diabetes, cesarean birth, and chromosomal abnormalities such as Down syndrome. Multiple-gestation secondary assisted reproduction also may be a factor in fetal loss.
Pregnancy after menopause: Very rarely, postmenopausal women have become pregnant through embryo donation and have successfully carried the pregnancy to term delivery. Prior to undergoing this procedure, the women had been undergoing hormone replacement therapy. Previously, it had been assumed that the postmenopausal uterus would not be capable of supporting the growth and development of an embryo. Pregnancies in older women are considered high risk for reasons similar to those related to mature pregnancy. Late in the third trimester, the woman may be instructed to keep a fetal activity record and undergo regularly scheduled nonstress tests.
Pregnancy Table for Expected Date of Delivery
Recommended Screening for Pregnant Women
|• Assessment of pregnant women for alcohol misuse and tobacco use|
|• HIV antibodies (blood test)|
|• Chlamydia and gonorrhea (antigen or culture) tests|
|• Hepatitis B virus (blood test)|
|• Rh incompatibility (blood test)|
|• Syphilis (blood test)|
|• Urinalysis for asymptomatic bacteriuria|
|• Nutritional assessment|
|• Assessment for intimate partner violence|
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