Fetal surveillance in late pregnancy and during labor

During early gestation, drugs have teratogenic effects and can be associated with structural anomalies in the fetus. Substance abuse can also have physiologic effects on the mother and fetus, including decreased uterine blood flow, increased vascular resistance, and an increase in fetal blood pressure. Women at increased risk for stillbirth should undergo antepartum fetal surveillance initiated at 32 weeks of gestation. Because of the high incidence of low birth weight, fetal anomalies, preterm delivery, and growth restriction in these patients, ultrasonography for appropriate pregnancy dating, a detailed anatomic survey, and cervical length should be performed at 20 weeks' gestation.