Medical Disorders During Pregnancy
- Armando G. Milano, PHD
Although relatively few medical disorders can prevent pregnancy, virtually the entire spectrum of disease can complicate it. This section highlights some of the most frequently encountered medical disorders during pregnancy. In each case the unique interaction of medical disease and pregnancy is emphasized. Recommendations for treatment reflect the understanding that management of serious medical disorders frequently requires the use of medications potentially harmful to the fetus. Yet many untreated medical diseases are detrimental to the fetus and jeopardize the health of the mother as well.
Diabetes Mellitus, Type I
Beginning in early gestation, glucose and various gluconeogenic amino acids reach the fetus against a concentration gradient by facilitated diffusion.
Gestational diabetes is defined as carbohydrate intolerance of variable severity with onset during the present pregnancy.
Several special considerations of thyroid dysfunction during pregnancy should be kept in mind. First, signs and symptoms of disordered thyroid function may be mimicked by pregnancy itself.
Primary hyperparathyroidism does not appear to impair fertility, but it is known to result in a high rate of fetal complications such as spontaneous abortions, stillbirths, and neonatal tetany.
Prolactin-secreting adenomas account for approximately 30% of all pituitary adenomas. Fewer than 7% of patients with intrasellar microadenomas (size less than 10 mm) manifest clinical evidence of tumor expansion during pregnancy.
Pregnancy is associated with a variety of anatomic and functional changes of the kidneys and lower urinary tract. Caliceal, pelvic, and ureteral dilatation occurs during the first trimester and persists throughout gestation up to 12 weeks postpartum. Hydronephrosis and hydroureter have direct clinical consequences because urinary stasis contributes to the propensity to develop pyelonephritis in women with asymptomatic bacteriuria.
Hypertension is among the most commonly seen medical disorders of pregnancy. Up to 30% of pregnancies are complicated by hypertension, about half being chronic essential hypertension. Preeclampsia occurs in 5% to 10% of pregnant women. Arterial blood pressure greater than 140 mm Hg systolic and 90 mm Hg diastolic or a rise in blood pressure more than 30 mm Hg systolic and 15 mm Hg diastolic over baseline warrant a diagnosis of hypertension. A useful classification of hypertensive disorders of pregnancy is presented in Box 372-1.
Preeclampsia and Eclampsia
Preeclampsia is a multiorgan disease unique to pregnancy. The condition is characterized by the development of elevated blood pressure, proteinuria, and generalized edema.
Without documentation of elevated blood pressure before pregnancy, chronic hypertension can only be presumed. The vast majority of patients who present with elevated blood pressure before the twentieth week of gestation, however, have chronic hypertension.
Late or Transient Hypertension
Hypertension without proteinuria or abnormal edema that develops late in gestation or in the puerperium is referred to as late or transient hypertension.
Hypertensive States of Pregnancy
Normal pregnancy is accompanied by changes in blood volume, heart rate, blood pressure, cardiac output, and ventilation. Cardiac output begins to rise during the first trimester, peaks at an approximate 40% increase by 20 to 24 weeks, then declines during the last 8 weeks of gestation. The increase in cardiac output during early pregnancy is primarily caused by an increase in stroke volume. As pregnancy advances, heart rate increases, whereas stroke volume falls to nonpregnant levels.
Thromboembolic disease is the leading cause of nonobstetric postpartum maternal mortality. In the United States, one half of all thromboembolic events in women younger than 40 years are related to pregnancy.
Asthma is one of the most common illnesses and the most common obstructive pulmonary disease encountered during pregnancy. Asthma may occur for the first time during pregnancy.
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