Hypotension in pregnant women: a population-based case-control study of pregnancy complications and birth outcomes

Hypotension is frequent in pregnant women; nevertheless, its association with pregnancy complications and birth outcomes has not been investigated. Thus, the aim of this study was to analyze the possible association of hypotension in pregnant women with pregnancy complications and with the risk for preterm birth, low birthweight and different congenital abnormalities (CAs) in the children of these mothers in the population-based data set of the Hungarian Case-Control Surveillance of CAs, 1980-1996. Prospectively and medically recorded hypotension was evaluated in 537 pregnant women who later had offspring with CAs (case group) and 1268 pregnant women with hypotension who later delivered newborn infants without CAs (control group); controls were matched to sex and birth week of cases (in the year when cases were born), in addition to residence of mothers. Over half of the pregnant women who had chronic hypotension were treated with pholedrine or ephedrine. Maternal hypotension is protective against preeclampsia; however, hypotensive pregnant women were at higher risk for severe nausea or vomiting, threatened abortion (hemorrhage in early pregnancy) and for anemia. There was no clinically important difference in the rate of preterm births and low birthweight newborns in pregnant women with or without hypotension. The comparison of the rate of maternal hypotension in cases with 23 different CAs and their matched controls did not show a higher risk for CAs (adjusted OR with 95% confidence intervals: 0.66, 0.49-0.84). In conclusion, a higher risk for CAs and other adverse birth outcomes was not found in the offspring of pregnant women with hypotension, but maternal hypotension was associated with a higher risk of some pregnancy complications.