Low prevalence of high blood pressure in pregnant women in Burkina Faso: a cross-sectional study

Maternal mortality is unacceptably high. Worldwide, approximately 295,000 women died during pregnancy, childbirth and the postpartum period in 2017 [1]. Every day, approximately 810 women die from preventable causes related to pregnancy and childbirth [1].

The vast majority of these deaths (94%) occur in low-resource settings and most could have been prevented [1]. Numerous factors, such as hypertensive disorders of pregnancy (HDP), have been identified as being responsible for this mortality [2‐5]. According to a recent report from the World Health Organization (WHO), HDP is the leading cause of maternal mortality in some African settings [3]. HDP is a multisystem disorder that includes gestational hypertension, chronic hypertension with superimposed pre-eclampsia and pre-eclampsia. HDP contribute to 14% of maternal mortality worldwide and 16% in sub-Saharan Africa [3, 4]. Globally, 2.7% of pregnant women suffer from HDP, whereas the incidence of chronic hypertension is 0.29%; the prevalence of HDP is 2.16% in pre-eclampsia and 0.28% in eclampsia [6]. Many studies have investigated the prevalence of high blood pressure (HBP) in pregnant women, with most studies being conducted in tertiary hospitals [7‐9]. Very different prevalence of HDP has been reported, ranging from 1.3% in China to 26.7% in Tanzania [10, 11]; in 2022, a prevalence of 0.3% in women of childbearing age was reported in sub-Saharan Africa [12]. Few studies, however, have investigated HBP prevalence at the healthcare system level; furthermore, no studies have been conducted in Burkina Faso.

The primary goal of WHO recommendations is to improve the quality of care and outcomes for pregnant women, particularly related with the management of HDP [13, 14]. Women with HDP should have a comprehensive care plan that includes prenatal counselling, frequent visits during pregnancy, timely birth, appropriate intrapartum monitoring and care and postpartum follow-up. Management involves advice during each stage of pregnancy to ensure that the woman is aware of the risks to herself and her fetus [13, 15]. In an era where data govern health priorities, evaluation of the prevalence of HBP in particular settings has important implications for surveillance [16, 17]. This study was conducted to determine the prevalence of HBP among pregnant women at the first level of the healthcare system in Burkina Faso and to investigate associated risk factors.

Among the six health facilities, 1027 women received antenatal care and all agreed to participate. Mean age of the participants was 25.8 ± 6.0 years and of them, 14.4% (148/1027) were < 20 years, out of whom 17.4% (76/437) lived in semi-urban areas, and 12.2% (72/590) in rural areas. Most participants were younger than 20 years in the first pregnancy 71.8% (732/1027) and had not received formal education (63.3%; 650/1027) (Table 1).

The overall prevalence of HBP was 1.4% (14/1027; 95% CI 0.7–2.3). Prevalence rates for each group were as follows: in the group aged 20–29 years (1.4%; 95% CI 0.7–2.7), without formal education (1.7%; 95%CI 0.9–3.0), in low income households (1.7%; 95% CI 0.8–3.9), without occupation (1.5%; 95% CI 0.8–2.8), in the third trimester (3.0%; 95% CI 1.1–7.7), primipara (1.6%; 95% CI 0.8–3.2), and living in rural areas(1.6%; 95% CI 0.8–3.3). These differences were, however, not statistically significant (Table 2).

In the multivariable analysis, pregnancy trimester, maternal age, household income, occupation, parity, and residential area were not associated with HBP during pregnancy (Table 3).

The prevalence of HBP in pregnancy was low with 1.4% in Burkina Faso, similar to that reported in African (1.5%) and global studies (0.2%–9.2%) [20, 21]. In 2020, Gemechu et al. reported a prevalence of 0.9% (95% CI: 0.4–1.8) for only gestational hypertension in a systematic review and meta-analysis of 70 studies [4]. The prevalence found in our study is relatively high compared to the prevalence of 0.3% for women of childbearing age reported by Jiang et al. in 2022 [12]. However, large differences have been reported in the prevalence of HBP [8, 20, 20, 22‐24]. Berhe et al., reported a range of 8–46.4% in the prevalence of HBP in a systematic review of 258,602 pregnant women [25]. These differences could be explained by the participants’ age. A survey of HBP in China showed a prevalence of 12.7% in pregnant women aged ≥ 40 years compared to a prevalence of 4.3% in pregnant women aged 25–29 years [26]. HBP measurement methods have not been described in all studies therefore different methods may partially explain the differences in prevalence [4, 25]. In addition, differences might be due to sociocultural variability in maternal risk factors and differences in antenatal care accessibility [4].

Most prevalence studies, however, were conducted in referral hospitals and in urban settings where women with hypertension are concentrated for better management [7, 8, 11, 20, 23]. In Togo, the prevalence of hypertension was 12.5% in in a maternity department in an urban area [22]. In Burkina Faso, in the teaching hospital of an urban area, a prevalence of 9.6% was reported [18]. This is similar to the prevalence of 9.9% reported in a health facility in Ethiopia and 9.7% in a Nigerian teaching hospital [24, 25]. Our study was conducted at a first-level health facility. In our sample, more than 76% of the participants were < 30 years of age. Their young age and rural residential environment could explain the observed low prevalence. HBP may be more common in women aged > 35 years, although a high prevalence in women < 30 years of age has been reported in China and Ethiopia [25, 26].

Higher prevalence of hypertension among women in the third trimester of pregnancy (3%) than in the first trimester (0.7%) can be explained by the development of hypertensive disorders of pregnancy after 20 weeks [7]. Differences in prevalence rates in the literature also depend on the stage of pregnancy blood pressure measurement was done, considering the mid-pregnancy blood pressure drop occurring in uncomplicated pregnancies and the level of screening before pregnancy in different countries [27‐29].

Maternal age, household income, occupation, parity, and residential area were not associated with HBP during pregnancy in our study. Several studies have reported an association between sociodemographic characteristics [12, 20, 25]. This difference may be explained by the lack of statistical power because we conducted this study to identify the prevalence of HBP during pregnancy [30].

The prevalence of HBP among pregnancy women in the first level of health system care is significantly lower compared to prevalence’s reported in hospital studies. Pregnant women in resource-limited countries face a double burden due to maternal infections and common pathologies such as the hypertensive disorders that compromise perinatal and maternal outcomes of pregnancy. Public health surveillance, primary prevention activities, early screening, and treatment of HDP should be reinforced in all health facilities to reduce the burden of adverse pregnancy outcomes in Burkina Faso.