The Importance of Nonproteinuric Hypertension in Pregnancy

Abstract

Objective: To compare the prevalence of maternal and fetal complications in hypertensive pregnant women (excluding chronic hypertension) with and without proteinuria.

Methods: A prospective study of hypertensive pregnant women referred for physician care in a principal teaching hospital between 1987 and 1993: 740 pregnant women were diagnosed as having preeclampsia or gestational hypertension on the basis of (i) exclusion of essential or secondary forms of hypertension in pregnancy, (ii) hypertension arising after 20 weeks gestation and returning to normal blood pressure after delivery. Clinical management was by one physician in conjunction with that patient's obstetrician, according to a uniform departmental protocol. Proteinuria was defined as greater than 300 mg/day or persistently ≥ 1 g/L (i.e., 2+) on dipstick testing if 24-h urine was unobtainable.

Main Outcome Measures: Maternal complications were: thrombocytopenia, renal insufficiency, liver disease, neurological abnormalities, and severe hypertension (≥ 170/110 mm Hg). Fetal complications were: perinatal mortality; small for gestational age. Birth weight was recorded.

Results: Only 17% had true proteinuria. Substantially more women would have had this diagnosis (inaccurately) if <1 g/L (2+) on dipstick testing alone was accepted. There was a higher prevalence of all maternal complications. and perinatal mortality was higher and birth weight lower in women with proteinuria. However, similar maternal complications still occurred in 4% to 13% of women without proteinuria.

Conclusions: Proteinuria is associated with a greater prevalence of maternal and fetal complications of hypertensive pregnancy. However, the absence of true proteinuria does not define a strictly benign subgroup as between 4% and 13% of hypertensive women without true proteinuria will also develop these complications. The outlook for the fetus in nonproteinuric women remains very good. Thus, nonproteinuric hypertensive pregnant patients should be managed with the same degree of vigilance as for proteinuric women.

Key Words:

• Hypertension
• Maternal Complications
• Perinatal mortality
• Pre-eclampsia
• Proteinuria