Antepartum testing in the hypertensive patient: when to begin.

Antepartum testing has been recommended for patients whose pregnancies are complicated by hypertension. Although this is considered accepted practice, there are little data available to help the clinician know when to start testing. To help answer this question in patients with chronic hypertension and nonproteinuric pregnancy-induced hypertension, we reviewed the results of all antepartum tests between 1976 and 1987 in patients with these diagnoses. The primary mode of surveillance in the majority of our patients was the contraction stress test. We determined when patients first had positive contraction stress test results and when intervention occurred because of an abnormal antepartum test result. There were a total of 917 patients tested with these diagnoses. Fifty-three (5.8%) of these patients had at least one positive contraction stress test result. Twenty-two patients were delivered of infants before 35 weeks' gestation because of abnormal antepartum test results. Those with early intervention (less than 35 weeks' gestation) could not be differentiated from those with later intervention (greater than or equal to 35 weeks' gestation) by maternal age, diastolic blood pressure, or systolic blood pressure at the time of testing. The majority of patients who were delivered of infants before 35 weeks' gestation had a concomitant diagnosis of systemic lupus erythematosus, intrauterine growth retardation, diabetes mellitus, or superimposed preeclampsia. On the basis of when compromise was evident, patients with these diagnoses may require testing to be started as early as the fetus is considered viable. However, in those without these diagnoses, the clinician may delay the beginning of testing until 33 weeks' gestation without significant risk of pregnancy loss before testing.