Low-dose aspirin does not prevent pre-eclampsia, small birthweight in high-risk women

Among women who are deemed high-risk for pre-eclampsia by Doppler examination, treatment with low-dose aspirin appears to have no significant clinical benefit, a recent study has found.

Researchers conducted a randomized, blinded, and parallel-group trial of 1,110 women who were given 160-mg aspirin (n=550) or placebo (n=550). All participants had a lowest pulsatility index >1.7 or bilateral protodiastolic notching or both uterine arteries, as determined by an ultrasound. The main outcome was the incidence of pre-eclampsia or infant birthweight ≤5th percentile.

Pre-eclampsia or low infant birthweight occurred in 88 women in the low-dose aspirin group, yielding an incidence rate of 16 percent. Seventy-nine (14.4 percent) placebo comparators experienced the same outcome. The proportion difference of 1.6 did not correspond to a statistically significant difference, according to multivariate analysis (odds ratio [OR], 1.14, 95 percent confidence interval [CI], 0.82–1.58; p=0.45).

Complete-case analysis confirmed these findings, which showed that the primary outcome occurred in 14.1 percent and 13.3 percent in the low-dose aspirin and placebo groups, respectively (p=0.68).

Secondary outcomes, including pre-eclampsia alone, severe pre-eclampsia, preterm pre-eclampsia, mode of delivery, preterm delivery, and perinatal death, all occurred at comparable rates between the groups.

“Low-dose aspirin was not associated with a lower rate than placebo of either pre-eclampsia or FGR in women identified as at high risk of pre-eclampsia during a first-trimester uterine artery Doppler examination,” the researchers said. “We interpret our results cautiously because of the lack of power related to insufficient number of patients recruited.”