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Click here to view next page of this article Prenatal CareThe major goal of prenatal care is to ensure a healthy baby and a healthy mother. Although the pregnant woman should be aware of this goal, she should be counseled that, with current limitations in medicine and science, its achievement cannot be guaranteed, especially with regard to promising a normal baby. Specific objectives to achieve this goal include the following:
In an attempt to ensure a systematic approach to prenatal care, several standardized prenatal forms have been developed, some of which provide a built-in risk assessment system. Diagnosis of Pregnancy Commercial kits are available for the diagnosis of pregnancy, all of which depend on detection of human chorionic gonadotropin (hCG) by an antibody. The various techniques used to detect hCG include agglutination inhibition, Work During Pregnancy A woman who has an uncomplicated pregnancy and a normal fetus and who is employed where there are no greater potential hazards than those encountered in routine daily life in the community may continue to work without interruption until the onset of labor. In addition, she may resume working 4-6 weeks after an uncomplicated delivery. Work may be limited or contraindicated during pregnancy in patients with vaginal bleeding, a cervix that may not be able to hold a pregnancy to term, uterine malformation associated with perinatal loss, pregnancy-induced hypertension (PIH), fetal growth restriction, multiple gestations, a prior history of preterm birth, or hydramnios. Exercise During Pregnancy In the absence of obstetric or medical complications, a pregnant woman may engage in a moderate level of physical activity. Exercise will help a pregnant woman maintain cardiorespiratory and muscular fitness throughout Ultrasonography Ultrasound imaging methods are based on insonating target tissues with low-energy (<100 mW/cm2), high-frequency (3.5-7.5 MHz) sound waves and recording the intensity and the delay time for reflected echoes. These echo signals are converted to dots by a digital computer; the brightness of the dots reflects signal strength, and the position of the dots reflects the distance of the target from the transducer. Multiple emitting crystals may be lined up and excited Antepartum Surveillance Although most methods of antenatal testing have been evaluated extensively for their relative value in high-risk populations, there are very few data on low-risk populations. Centers vary regarding testing protocols, interpretation of test results, testing techniques, and timing and frequency. Indications for Testing Following are some common indications for testing:
For most of these fetal conditions, testing is begun when the diagnosis is established, usually in the third trimester. For long-standing fetal conditions or chronic maternal medical complications, the timing depends on the severity of the Nonstress Test The NST is generally accepted as the simplest screening test for fetal compromise in the antepartum period. It is best to carry out this test with the patient either in the slightly tilted, recumbent position or in the semi-Fowler position to minimize compression of the maternal vena cava by the uterus. The fetal heart rate (FHR) is recorded by using an external Doppler ultrasound device. An external tocodynamometer is used as well. The protocol for the NST generally involves recording the FHR for 20-40 minutes, with the patient pressing a marker button when there is fetal movement. There are various criteria for the number of accelerations required during a Biophysical Profile The BPP combines the NST with fetal ultrasound parameters. In a 30-minute period, the fetus should exhibit movements, breathing motions, and evidence of tone as described in Table 2. In addition, the amniotic fluid volume is assessed and the NST results are recorded. The total score obtained reflects the fetal status. A score of 8-10 is normal and correlates highly with normal fetal umbilical cord blood gases and a normal fetal outcome. A score of 6 is considered equivocal and generally warrants repeated testing within 12-24 hours or delivery if the fetus is mature. A score of 4 or less is highly predictive of fetal Contraction Stress Test The CST attempts to mimic labor by inducing mild uterine contractions. Contractions may be spontaneous or may be generated either by oxytocin or by nipple stimulation. The heart rate is monitored continuously and compared with the contraction pattern. The presence of late decelerations suggests that the fetus has lost some placental reserve. However, in various studies, approximately 50% of fetuses that had abnormal responses to the CST subsequently Fetal Movement The antepartum use of fetal movement counting (or kick counts) may decrease antepartum stillbirth rates in low-risk women. In the fetal movement test, the pregnant woman records the length of time that the fetus takes to make 10 movements. She may select any period of the day to count these movements, but fetuses are generally perceived to Fetal Umbilical Artery Velocimetry Recently, Doppler fetal umbilical artery velocimetry has been used to measure increased placental vascular resistance, which may potentially allow for the recognition of placental dysfunction. However, due to its low positive predictive value, Doppler ultrasonography is not a screening test for detecting fetal compromise in the general obstetric population. After 24 weeks of gestation, measurement of the relationship of peak systolic to diastolic flow velocities, with the systolic-diastolic ratio, pulsatility index, or resistance index, may offer insight into fetal compromise. The Fetal Therapy Fetal therapy, or fetal treatment, encompasses some routine therapies as well as cutting-edge fetal surgery. There are both routine and unusual circumstances in which specific medical or invasive therapy is directed at the fetus with a well-defined, serious condition. It is in these situations that the term fetal therapy is usually applied. Many such Medical Therapy There are two types of medical therapy. In one, medications are given to the mother solely to cross the placenta and reach the fetus. In the other, medications are given to the mother to change her status and thus affect the fetus. Fetal Lung Maturity Thyroid hormone also controls fetal pulmonary development. Several trials of maternal administration of Congenital Adrenal Hyperplasia Congenital adrenal hyperplasia is a recessively inherited disorder that results in salt wasting. Glucocorticoid Fetal Tachyarrhythmia In most cases of fetal tachyarrhythmia (ie, FHR >180 beats per minute), there is no underlying anatomic congenital heart disease. Children with this condition respond well to treatment, and the long-term prognosis is good. Untreated fetuses may become hydropic, and the mortality under these circumstances is substantial. Digoxin is used to treat Neonatal Alloimmune Thrombocytopenia When a fetus has neonatal alloimmune thrombocytopenia, the mother has a normal platelet count, which is unlike maternal immune thrombocytopenic purpura. Fetuses tend to have profound thrombocytopenia, which may result in Invasive Fetal Therapy Intravenous Therapy The most successful and widely used form of invasive fetal therapy is the direct transfusion of erythrocytes to fetuses with erythrocyte isoimmunization. A transfusion can be directed into the fetal peritoneal cavity or intravenously. The latter route has been used more extensively in recent years. This is discussed in greater detail in the "Complications of Pregnancy" section. Anemia is the most common other reason to give a fetus erythrocyte transfusions. Fetal anemia usually is discovered during examination of a fetus with nonimmune hydrops. If the fetus is found to be anemic from a reversible cause, fetal therapy may be warranted. The most common etiologies for reversible underlying anemia are a fetal-maternal hemorrhage or parvovirus B 19 infection with a resultant fetal hemolytic crisis. Stem cell transplantation has been suggested as a way of treating fetuses affected with certain genetic diseases. To date, this procedure has been successful only in a limited number of cases. Generally, stem cells are injected into the fetus in the first or early second trimester. Grafting of these cells into the fetal liver with subsequent function has been documented. Obstructive Uropathy Obstructive uropathy lends itself to early detection with ultrasonography. Posterior urethral valves or bladder outlet obstructions are the most common of these disorders, but the obstruction may be at any level of the urinary tract. In all cases of obstructive uropathy, the rationale behind treatment is that the obstruction itself will lead to permanent renal damage in the developing fetus. Obstruction of the urinary tract will lead to oligohydramnios and pulmonary hypoplasia, which is usually the cause of death in these neonates. Thus, the rationale for invasive therapy is that it Diaphragmatic Hernia Diaphragmatic hernia is a serious fetal anomaly with a high perinatal mortality rate. Although it may be associated with other fetal anomalies, more frequently it is isolated. Death of neonates from pulmonary hypoplasia is believed to be due to compression of the normal lung in utero by herniated abdominal contents. Various methods of in utero repair |