Blood pressure, and the aspirin that prevents preeclampsia
One of the genuinely effective things offered in pregnancy.
Preeclampsia is high blood pressure with organ involvement, usually after 20 weeks. It is the reason your blood pressure and urine are checked at every visit.
Low-dose aspirin genuinely reduces it in women at higher risk. In a randomized trial of 1,776 high-risk pregnancies, 150 mg of aspirin daily from 11 to 36 weeks reduced preterm preeclampsia from 4.3% to 1.6%. That is an absolute reduction of 2.7 percentage points, or about 37 women treated to prevent one case.
Across 23 trials and 26,952 women, aspirin reduced preeclampsia (relative risk 0.85), perinatal death (relative risk 0.79) and preterm birth (relative risk 0.80), with absolute reductions of roughly 1 to 6 percentage points for preeclampsia and 0.5 to 1.1 percentage points for perinatal death in the largest trials. It did not increase bleeding after birth.