Low-dose aspirin reduces the risk for preterm delivery

Takeaway

• In nulliparous women with singleton pregnancies from low-income and middle-income countries, early administration of low-dose aspirin (between 6 weeks and 0 days of gestation and 13 weeks and 6 days of gestation) was associated with a reduction in the incidence of preterm births before 37 weeks and perinatal mortality.

Why this matters

• Findings confirm the previously suggested benefit of low-dose aspirin in reducing the risk of preterm birth.

Study design

• In modified intention-to-treat (mITT) analysis, 11,544 nulliparous women from six countries with singleton pregnancies were randomly assigned to receive low-dose aspirin (81 mg daily; n=5780) or placebo (n=5764).
• Primary outcome: incidence of preterm birth (number of deliveries <37 weeks gestational age).
• Funding: Eunice Kennedy Shriver National Institute of Child Health and Human Development.

Key results

• Overall, the incidences of preterm birth at <37 weeks were lower in aspirin vs placebo group (11.6% vs 13.1%; RR, 0.89; 95%CI, 0.81-0.98; P=.012).
• Women in the aspirin vs placebo group had significant reductions in:
  • perinatal mortality (264 vs 309 per 1000 births; RR, 0.86; 95%CI, 0.73-1.00; P=.048);
  • foetal loss (303 vs 353 per 1000 pregnancies; RR, 0.86; 95%CI, 0.74-1.00; P=.039);
  • early preterm delivery (<34 weeks) (RR, 0.75; 95%CI, 0.61-0.93; P=.039); and
  • early preterm delivery (<34 weeks) and hypertensive disorders (RR, 0.38; 95%CI, 0.17-0.85; P=.015).
• No significant difference was seen in other maternal, foetal, and neonatal events between both groups.

Limitations

• The optimal dose and time of initiation of aspirin remained unclear.