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Aspirin Before Bed May Reduce Risk For Preterm Delivery, Gestational Hypertension And Preeclampsia: Presented at AHA-HBPR

By Peggy Peck
Special to DG News

ORLANDO, FL -- September 27, 2002 -- Aspirin appears to significantly reduce the incidence of preeclampsia, gestational hypertension, intrauterine growth retardation (IUGR) and preterm delivery, but the effect seems to be time dependant.

This research was presented Thursday at the American Heart Association's 56^th Annual High Blood Pressure Research Conference by Ramon C. Hermida, PhD of the University of Vigo, Vigo, Spain.

He said that administration of aspirin at bedtime is likely to be more effective because "the body's metabolism slows with sleep so the aspirin is present longer. Based on the results of this study, we would recommend that women who are at risk for gestational hypertension or preeclampsia be offered a trial of low dose aspirin beginning no later than the 16th week of pregnancy. This protective effect is not apparent when aspirin is initiated later in pregnancy."

Dr. Hermida and co-author Diane E. Ayala, MD, PhD enrolled 341 women, including 181 primipara. The women, at 12 to 16 weeks' gestation, were randomly assigned to one of six treatment groups: aspirin 100 mg on awakening, eight hours after awakening, or at bedtime, or to time matched placebo groups.

Blood pressure for each woman was automatically monitored for 48 consecutive hours every four weeks from the day of recruitment until delivery, as well as at puerperium, for a total of 2511 BP profiles. Effects of medication and time of ingestion upon BP and the incidence of complications were evaluated by ANOVA and non-parametric testing, respectively.

The results showed that aspirin taken on awakening had no effect compared to placebo but there was a statistically significant improvement in blood pressure among the women who took aspirin eight hours after awakening. "But the most significant effect was observed with bedtime treatment," he said. At bedtime there was a mean reduction of 12.6/8.5 mmHg in 24-hour mean systolic/diastolic BP at delivery, Dr. Hermida said. Differences in BP among women receiving ASA at different circadian times disappeared at puerperium (P>0.096).

An aspirin at bedtime was associated with a 1.7 percent incidence of preeclampsia compared to 14.3 percent in the placebo group. The rates for gestational hypertension, IUGR and preterm delivery were 6.8 percent, 3.4 percent and 0 percent in the bedtime aspirin group compared to rates of 30.4 percent, 16.1 percent, and 17.9 percent respectively in the bedtime placebo group.

Dr. Hermida said that an aspirin eight hours after awakening or at bedtime also was associated with increased birth weight and gestational age at delivery.

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