This page has moved. Click here to view.
HYPERTENSION
Hypertensive disease complicates 6-8% of all pregnancies in the United States and is one of the major causes of maternal death. Hypertensive disease also significantly increases perinatal morbidity and mortality. Two distinct entities are commonly encountered in pregnant women: chronic hypertension and PIH. These two conditions may coexist; in fact, the risk of developing PIH is significantly increased in women with underlying chronic hypertension. Pregnancy-induced hypertension is a multiorgan disease process that may involve much more than elevated blood pressure. Sev-eral clinical subsets are recognized, depending on end-organ effects. Some such subsets have traditionally been given distinct labels, for example, preeclampsia when renal involvement leads to proteinuria, eclampsia when central nervous system involvement leads to seizures, and more recently, HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome when the clinical picture is dominated by hematologic and...
Clinical Manifestations
Hypertension is defined as a sustained blood pressure increase to levels of 140 mm Hg systolic or 90 mm Hg diastolic. Blood pressure may depend greatly on patient position; ideally, measurements should be taken in a uniform manner at each prenatal visit; the proper cuff size should be used and...
Ordinarily, PIH has its onset after 20 weeks of gestation, and chronic hypertension is defined as hypertension devel-oping before 20 weeks of gestation. Patients with gestational trophoblastic disease are an exception; they can develop classic features of PIH during the first or second trimester hypertension, pregnancy, toxemia, preeclampsia, pregnancy-induced hypertension, toxema, toxemea.
Patients who develop PIH and, in addition, manifest end-organ involvement or fetal growth restriction are considered to have severe disease. Early delivery should be considered for such women, often despite fetal immaturity. Manifesta-tions that can indicate severe disease are listed in the box.
Clinical Manifestations of Severe Disease in Patients with Pregnancy-Induced Hypertension
• Blood pressure >160-180 mm Hg systolic or
>110 mm Hg diastolic
• Proteinuria >5 g/24 h (normal <300 mg/24 h)
• Elevated serum creatinine
• Grand real seizures (eclampsia)
• Pulmonary edema
• Oliguria <500 mL/24 h
• Microangiopathic hemolysis
• Thrombocytopenia
• Hepatocellular dysfunction (elevated alanine aminotransferase, aspartase).
• Intrauterine growth restriction or oligohydramnios
• Symptoms suggesting significant end-organ involvement: headache, visual disturbances, or epigastric or right-upper-
quadrant pain
Pathophysiology
The etiology of PIH is unknown. However, it is well established that the disease process occurs most often in women who are pregnant for the first time, women with multiple gestation, and women with certain vascular disorders such as those seen with insulin-dependent diabetes, lupus erythematosus, renal disease, and chronic hypertension. The major
pathophysiologic derangement is vasospasm.
There are several potential maternal consequences of PIH, including cardiovascular and hematologic effects and regional perfusion abnormalities. For example, cardiac output is increased 30-50% in normal pregnant women and is not altered significantly in patients with PIH. The control of peripheral resistance in normal and PIH-complicated pregnancies is critical to understanding blood pressure control because blood pressure is the product of cardiac output times peripheral resistance, and peripheral resistance is increased in women with PIH. This likely occurs as the consequence of an increased sensitivity of the maternal vasculature to a variety of
Prevention
Several studies have addressed the use of low doses of aspirin for the prevention of PIH. A meta-analysis of six con-trolled trials demonstrated a significant reduction in IUGR and cesarean delivery in women judged to be at high risk for PIH based on various criteria. No reduction in perinatal death was seen, and there were no
BLEEDING IN THE SECOND HALF OF PREGNANCY
Third-trimester bleeding is a phrase commonly used as a "diagnosis" for bleeding occurring late in \
MULTIPLE GESTATION
Multiple gestation occurs in about 1.5% of all births. Although multiple pregnancies of higher order (greater than three) presently constitute a relatively small component of the total, these numbers are increasing as a result of the widespread use of assisted reproductive technologies.
Twins may result either from the splitting of a single fertilized ovum into two genetically identical individuals (monozygotic) or when two separate ova are each fertilized by a sperm, leading to genetically distinct
Management
Antenatal management should include attention to adequate nutrition, avoidance of strenuous physical activity, frequent prenatal visits, and counseling on symptoms of preterm labor, PROM, and hypertensive disorders of pregnancy. Ultrasound assessment of fetal growth and amniotic fluid volume should be
Embryo Reduction
The higher-order multiple gestations resulting from assisted reproductive technologies have many associated problems. Of greatest significance to the offspring is the increased risk of preterm delivery, which is directly
ISOIMMUNIZATION
Despite dramatic progress in the management and prevention of hemolytic disease of the fetus and newborn caused by maternal blood group immunization, it continues to be an important cause of infant morbidity and mortality in the United States. In 1970, the incidence of hemolytic disease in newborns was approximately
FETAL GROWTH RESTRICTION
Infants born at or below the third percentile of mean weight for gestational age, with clinical evidence of dysfunctional or abnormal growth, are described as growth restricted. The perinatal mortality rate of these infants is five times higher than that of normal infants. Approximately one half of growth-restricted babies show wasting of soft tissue and muscle mass, especially in the cheeks, arms, buttocks, and thighs. The
PRETERM LABOR AND DELIVERY
Any birth occurring before the end of 37 weeks of gestation is considered preterm. The incidence is between 8% and 10% of all births, and preterm births account for more than 60% of non-anomalous-related neonatal TOCOLYSIS
Methods to arrest preterm labor include bed rest and tocolytics. The most widely used tocolytic drugs are magnesium sulfate, beta-mimetics, prostaglandin synthetase inhibitors, and calcium channel blockers. Recently, atosiban (an oxytocin analog) and nitric oxide donor drugs have been used. The safety and
CORTICOSTEROID THERAPY
Maternal corticosteroid treatment with betamethasone and dexamethasone has been shown in several controlled trials to decrease the incidence of respiratory distress syndrome. The National Institute of Child Health and Human Development, together with the Office of Medical Applications of Research of the National
PREMATURE RUPTURE OF MEMBRANES
Rupture of membranes that occurs before the onset of labor is described as premature (PROM). Preterm PROM occurs before 37 weeks of gestation. It is preferable to specify rupture of membranes according to
POSTTERM GESTATION
The average length of human pregnancy, calculated from the first day of the last menstrual period, is 280 days (ie, 40 weeks). By current definition, a postterm pregnancy is a gestation lasting 42 weeks or more (ie, 295 days from the first.day of the last menstrual period). The incidence ranges from 4% to 14%, with an