Abstract

Introduction Nigeria has one of the highest maternal mortality ratios in the world (814/100,000 live births), and in a recent nationwide, cross-sectional study, 29.0% of all maternal deaths were attributed to the hypertensive disorders of pregnancy. However, the reported prevalence of the hypertensive disorders of pregnancy ranges greatly from 10% to 22% in Southern Nigeria and there are limited data describing clinically accurate, population-level estimates. Objectives As part of the Community Level Interventions for Pre-eclampsia (CLIP) Study [NCT01911494], the aim of this analysis is to record and report community-level prevalence rates of the various hypertensive disorders of pregnancy in Ogun State, Nigeria. Methods Clinical signs and symptoms of the hypertensive disorders of pregnancy were assessed and recorded for 8790 pregnancies, at primary health centers across five local government areas (Remo North, Ijebu Northeast, Odeda, Yewa South and Ogun Waterside). Proteinuria was measured by dipstick and blood pressure was assessed using a semi-automated, validated blood pressure device at each antenatal or postnatal visit. The classification criteria used for the hypertensive disorders of pregnancy is based on the Society of Obstetricians and Gynaecologists of Canada guidelines (2014). To account for the different gestational ages at enrolment, mixed hypertension is used to describe conditions of pre-existing hypertension, gestational hypertension or pre-eclamptic toxemia. Pre-eclampsia is defined as the presence of hypertension with either (i) proteinuria, or (ii) one or more adverse conditions (headache, visual disturbances, chest pain/dyspnea, abdominal pain), or (iii) one or more severe complications (coma, stroke, seizures, vaginal bleeding). Statistical analysis was undertaken using R software, and 95% confidence intervals were used to describe prevalence rates. Results The mean maternal age of 8790 enrolled women was 27.2 (+/- 5.6) years, and 31.3% were nulliparous (n = 2752). The mean gestational age at enrolment was 26.5 (+/-7.0) weeks. Hypertension, defined as sBP Math Eq 140 mm Hg and/or dBP Math Eq 90 mm Hg, was observed in 10.3% ([CI 6.5–14.1%]; n = 720) of the 7016 completed pregnancies. Severe hypertension (sBP Math Eq160 mm Hg and/or dBP Math Eq 110 mm Hg) was identified in 130 (1.9% [CI 0.9–2.8%]) completed pregnancies and 590 (8.4% [CI 4.7–12.1%]) pregnancies were identified with non-severe hypertension (140 mm Hg Math Eq sBP Math Eq160 mm Hg; 90Math Eq dBP Math Eq 110). Of the 6709 pregnancies evaluated at gestational age >20 weeks, 10.4% ([CI 6.7–14.0%]; n = 696) presented with mixed hypertension whereas 3.3% ([CI 1.9–4.6%], n = 219) showed mixed hypertension with evidence of pre-eclampsia. Conclusion The prevalence of hypertension in pregnancy of 10.3% observed in this cohort is comparable to findings reported in studies in Southern Nigeria. Antihypertensive therapy for non-severe pregnancy hypertension decreases the risk of severe hypertension and associated complications; therefore, a prevalence of 8.4% non-severe hypertension could benefit from treatment with oral antihypertensives. These findings can inform future research and programmatic activities.