The prevalence of and risk factors for stillbirths in women with severe preeclampsia in a high-burden setting at Mpilo Central Hospital, Bulawayo, Zimbabwe

Introduction

Stillbirths remain a major global concern with a reported estimate of 2.6 million third trimester stillbirths having occurred in 2015 [1]. This figure remains unacceptably high [2]. The majority of stillbirths, nearly 98% occur in low- and middle-income countries (LMICs) [3]. Stillbirths have widespread negative effects on parental mental health [4]. One important cause of stillbirths in LMICs is preeclampsia, where studies from Ghana [5], Zimbabwe [6], and Nigeria highlight that women with preeclampsia were eight times more likely to experience stillbirths (adjusted odds ratio (aOR) 8.24, 95% confidence interval (CI) 3.01–22.51) [7]. Other important causes of stillbirths include malaria, syphilis, prematurity, antepartum haemorrhage, placental abruption, maternal age older than 35 years and unspecified bacterial infections [1, 5], [6], [7], [8].

Sub-Saharan Africa has some of the highest rates of stillbirth. In Zimbabwe, the prevalence of stillbirth was found to be 3.0% at Mpilo Central Hospital [6] and in Northern Tanzania it was found to be 3.6% [8]. There have been efforts to reduce stillbirths to meet the targets set by the Every Newborn Action Plan (<12 per 1,000 births). At a low-resource setting in Zimbabwe, clinical leadership and accountability was found to reduce fresh full-term intrapartum stillbirths [9]. Access to planned and emergency caesarean sections have been found to reduce stillbirths [9], [10], [11]. If effective intervention(s) could be targeted to women at greatest risk of stillbirth, then it is anticipated that the stillbirth rate would decrease. Therefore, the aim of this study was to determine the prevalence of and risk factors for stillbirths amongst women with severe preeclampsia in a low resource setting. It was hypothesised that there would be risk factors for stillbirth in women with severe preeclampsia.

Materials and methods

This sub-analysis was part of a doctoral research programme. The main study was a retrospective cross-sectional study of all women with severe preeclampsia covering the period January 1, 2016 to December 31, 2018, at Mpilo Central Hospital, Bulawayo, Zimbabwe. Therefore, some of the participants include in this sub-analysis were also analysed in prior studies on the same subject of severe preeclampsia [12], [13], [14], [15], [16], [17], [18], [19]. This sub-analysis only included women who were above 28 weeks’ gestation, so that if their babies demised, they met the WHO definition of a stillbirth [20].

The outcome measure was birth outcome. A stillbirth was defined as a baby born after 28 weeks’ of gestation without signs of life as appropriate for low-resourced countries. Severe preeclampsia was defined here as systolic blood pressure ≥160 mmHg, diastolic blood pressure ≥110 mmHg or there was hypertension ≥140/90 mmHg in the presence of proteinuria or abnormal biochemical or haematological blood indices [15, 21]. Data regarding socio-demographic information, past obstetric history, maternal signs and symptoms, laboratory test results, maternal complications, birth-weight and fetal sex were obtained from the clinical records. The Mpilo Ethics Committee and the Medical Research Council of Zimbabwe approved the research programme, approval number MRCZ/A/2483.

Results

There were 46 stillbirths out of the 469 women that met the inclusion criteria, giving a stillbirth prevalence of 9.8% amongst women with severe preeclampsia. 31 (67.4%) of the stillbirths were male and 15 (32.6%) were female.

Women who had a stillbirth differed in terms of maternal age (p=0.002), gravidity (p=0.01), parity (p=0.01), and gestational age (p<0.0001) from those who had a live born baby. The rest of the results of the statistical differences can be seen in Table 1.

Table 2 shows the univariate and multivariate analysis of predictor variables and stillbirths. Unbooked status was an independent risk factor for stillbirths in women with severe preeclampsia, who were 3 times more likely to experience a stillbirth compared to those that were booked for antenatal care (aOR 3.01, 95% CI 2.20–9.10, p=0.05). Women with frontal headaches and severe preeclampsia were 2 times more likely to suffer a stillbirth compared to those without frontal headaches (aOR 2.33, 95% CI 0.14–5.78, p=0.01). Women with vaginal bleeding with abdominal pain and severe preeclampsia were 5 times more likely to experience a stillbirth compared to those without vaginal bleeding with abdominal pain (aOR 4.71, 95% CI 1.12–19.94, p=0.04).

Women with diastolic blood pressure of ≥150 mmHg and severe preeclampsia were 15 times more likely to experience a stillbirth compared to those with diastolic blood pressure of <110 mmHg (aOR 15.04, 95% CI 1.78–126.79, p=0.01). Women with platelet count 0–49 × 10⁹/L were 3 times more likely to suffer a stillbirth compared to those with platelet counts ≥150 × 10⁹/L (aOR 2.80, 95% CI 1.26–6.21, p=0.01), whereas those with platelets count 50–99 × 10⁹/L were 2.5 times more likely to suffer a stillbirth (aOR 2.48, 95% CI 0.99–6.18, p=0.05). Male babies were 3 times more likely to be stillborn compared to female babies (aOR 2.75, 95% CI 1.37–5.53, p=0.04).

Discussion

Information from this sub-analysis showed that the prevalence of stillbirths was 9.8% amongst women with severe preeclampsia, this confirms that this group of women are at a significantly increased risk of stillbirth. The stillbirth prevalence of 9.8% at Mpilo Central Hospital was similar to the 9.0% found in Nigeria, a similar low-resource setting [22]. Focussed efforts to improve the management of severe preeclampsia may have a positive impact on the number of stillbirths in low-resource settings. Such focussed efforts could entail the establishment of specialised antenatal services or emergency care for women who develop hypertensive disorders of pregnancy. The general prevalence of stillbirths at the hospital was 3.0% [6], but this study has revealed that amongst severe preeclampsia the prevalence of stillbirths was 9.8% which justifies the need for a more dedicated and focussed approach in these women to improve perinatal outcomes.

Conclusions

This study determined that the prevalence of stillbirths was increased in women with severe preeclampsia. Multivariable logistic regression identified independent risk factors for stillbirths in women with severe preeclampsia. These emphasise the importance of ensuring women book for and receive adequate antenatal care and that clinicians caring for women with severe preeclampsia recognise symptoms and clinical signs associated with stillbirth and intervene to control severe blood pressure. Focussed and dedicated antenatal clinics should be considered as a high priority by policy makers to reduce the burden of stillbirths on parents and the high global stillbirth deaths.