The effectiveness of low-dose aspirin for the prevention of hypertensive disorders of pregnancy in a sub-Saharan Africa Country: A randomized clinical trial

Objective

To evaluate whether a daily dose of low-dose aspirin (LDA) can prevent hypertensive disorders of pregnancy (HDP), including preeclampsia, among pregnant women in a South African cohort, and to assess its impact on related maternal and fetal outcomes, such as preterm birth and neonatal complications.

Study design

This single-center, open-label, parallel-group randomized controlled trial (RCT) was conducted at a regional hospital in Durban, KwaZulu-Natal, South Africa, from May 2021 to March 2024. A total of 423 pregnant women, aged 18 years or older with singleton pregnancies between 12 and 20 weeks of gestation, were randomized to receive either 162 mg of LDA daily or standard care. The primary outcome was the incidence of HDP, while secondary outcomes included early-onset preeclampsia (EOPE), preterm birth, low birth weight (LBW), and neonatal death. Data analysis used relative risk (RR) and 95 % confidence intervals (CIs).

Results

Of the 423 women, 209 were in the LDA group and 214 in the control group. The incidence of HDP was significantly lower in the LDA group (6.2 % vs. 25.2 %; RR = 0.25, 95 % CI [0.14–0.44], p < 0.001), corresponding to a 75 % reduction in HDP risk, with an absolute risk reduction (ARR) of 19 % and a number needed to treat (NNT) of 5.3. EOPE was reduced (2.4 % vs. 14.0 %; RR = 0.17, 95 % CI [0.07–0.41], p < 0.001), as was preterm birth (6.7 % vs. 26.2 %; RR = 0.26, 95 % CI [0.15–0.45], p < 0.001). There were no significant differences for LBW or neonatal death. Sensitivity analysis confirmed the importance of initiating LDA before 16 weeks, showing continued reductions in HDP incidence with early initiation.

Conclusion

LDA significantly reduces the risk of HDP, EOPE, and preterm birth, particularly when initiated before 16 weeks of gestation. These findings support the use of LDA for preventing hypertensive disorders of pregnancy in low-resource settings and underscore the value of early intervention for improved maternal and fetal outcomes.