(277) Early-onset hypertensive disorders of pregnancy associated with high perinatal mortality in Dar es Salaam, Tanzania

Objective: To estimate the risk of adverse perinatal outcomes associated with early (< 34 weeks) vs late (> 34 weeks) presentation of hypertensive disorders of pregnancy (HDPs) in a resource-limited setting.

Study Design: We performed a secondary analysis of a randomized noninferiority trial comparing 500 mg vs 1500 mg calcium supplementation daily for preeclampsia (PE) prevention among nulliparous women (n=11,000) in Dar es Salaam, Tanzania (2019-2023). Women were followed monthly during antenatal visits through delivery with serial measurements of blood pressure and urine dipstick for protein. We compared risk of adverse perinatal outcomes associated with early (< 34 weeks) vs late (> 34 weeks) presentation of HDPs in multivariable regression models.

Results: Of the 11,000 women enrolled in the trial, 162 (1.5%) were diagnosed with GHTN, 121 (1.1%) with PE without severe features and 194 (1.8%) with PE w/ severe features. Early (< 34 weeks) presentation was associated with a marked increase in the risk of adverse perinatal outcomes across all HDP categories (TABLE). The prevalence of perinatal mortality for early compared to late onset of GHTN was 32.0% vs 5.0% (aRR 5.0; 95% CI: 2.2, 11.1); for PE without severe features 26.1% vs 4.6% (aRR: 8.5; 95% CI: 2.0, 36.7); and for PE with severe features 47.5% vs 8.8% (aRR: 5.8; 95% CI: 3.0, 11.4). Early onset HDP also was strongly associated with preterm birth and low birthweight across HDP phenotypes.

Conclusion: Adverse perinatal outcomes were significantly higher among pregnancies with HDPs that presented earlier in gestation (< 34 weeks) compared to later in this large pregnancy cohort from Tanzania.  Our findings confirm the importance of early detection and management of HDP. The high rates of perinatal mortality and other adverse outcomes underscore the critical need for scaling up interventions, such as prophylactic aspirin or calcium supplementation, that can prevent or delay the onset of HDP in settings where access to routine neonatal intensive care is limited or currently unavailable.