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USPSTF recommends low-dose aspirin for women at high risk for preeclampsia
The US Preventive Services Task Force recommended low-dose aspirin for pregnant women at high risk for preeclampsia.
The task force concluded that pregnant women at high risk for preeclampsia should take aspirin 81 mg/day after 12 weeks of gestation. The recommendation differs from the 1996 recommendation, when the task force found insufficient evidence for benefit and potential risk for placental abruption if pregnant women at high risk for preeclampsia took aspirin.
Evidence that has emerged since 1996, however, indicates that low-dose aspirin is associated with a reduction in risk for preeclampsia, preterm birth and intrauterine growth restriction, Michael L. LeFevre, MD, MSPH, chair of the USPSTF, and colleagues wrote.
According to the USPSTF, preeclampsia affected 3.8% of deliveries in the United States in 2010 and accounts for 15% of US preterm births. Preeclampsia and eclampsia are directly responsible for 12% of maternal deaths in the United States, the task force wrote.
The task force defined preeclampsia as onset of hypertension (systolic BP >140 mm Hg/diastolic BP >90 mm Hg) and proteinuria (≥0.3 g of protein in the urine within a 24-hour period) any time after 20 weeks of pregnancy. It also defined preeclampsia as hypertension without proteinuria but with one of the following: thrombocytopenia, impaired liver function, renal insufficiency, pulmonary edema or cerebral or visual disturbances.
Risk reduction
The USPSTF evaluated 15 randomized controlled trials of maternal and perinatal health benefits in women at increased risk for preeclampsia and 13 randomized controlled trials of preeclampsia incidence.
Its meta-analysis found that low-dose aspirin in women at increased risk for preeclampsia was associated with a 14% reduction in risk for preterm birth (pooled RR=0.86; 95% CI, 0.76-0.98; I2=33.2%), a 20% reduction in risk for intrauterine growth restriction (pooled RR=0.8; 95% CI, 0.65-0.99; I2=36%) and an increase in mean birth weight of infants (pooled weighted mean difference, 130 g; 95% CI, 36.2-223.3; I2=60%). It was not associated with a reduction in perinatal mortality (pooled RR=0.81; 95% CI, 0.65-1.01; I2=0%).
The task force also found that low-dose aspirin in women at increased risk for preeclampsia was associated with a 24% reduction in risk for preeclampsia (pooled RR=0.76; 95% CI, 0.62-0.95; I2=40.5%). It did not find any effect on preeclampsia prevention by timing of aspirin initiation or dosage of aspirin.
The USPSTF also concluded that the harms of low-dose aspirin when used by pregnant women “are no greater than small.” It evaluated 19 randomized controlled trials and two observational studies to evaluate maternal, perinatal and developmental harms.
It found that use of aspirin in pregnant women was not associated with placental abruption (pooled RR=0.92; 95% CI, 0.98-1.48; I2=36.4%). It also found no harm related to perinatal mortality associated with aspirin use (pooled RR=0.93; 95% CI, 0.76-1.11; I2=0%) and a trend toward a benefit in women at increased risk for preeclampsia (pooled RR=0.81; 95% CI, 0.65-1.01).
Research gaps
More research is needed on the effect of low-dose aspirin on the development of preeclampsia and how magnitude of response to aspirin may change with individual or combined risk factors for preeclampsia, LeFevre and colleagues wrote. They also identified a need for future research in high-risk subgroups, including black women and nulliparous women. “Future trials should recruit adequate numbers of women from racial/ethnic populations that are at disproportionate risk … in order to have sufficient power to determine the effectiveness of different aspirin dosages and timing of initiation in these high-risk groups,” they wrote.
The task force also included guidance on how to classify women as low risk, moderate risk or high risk for preeclampsia. It recommended low-dose aspirin for women with at least one high-risk factor or several moderate-risk factors.
The USPSTF recommendation is similar to a recommendation from the American Heart Association and American Stroke Association, which states that women with chronic primary or secondary hypertension or previous pregnancy-related hypertension take low-dose aspirin from 12 weeks until delivery.
Disclosure: The members of the USPSTF report no relevant financial disclosures.