Incidence and determinants of perinatal mortality in five urban hospitals in Dar es Salaam, Tanzania: a cohort study with an embedded case-control analysis

Introduction: Tanzania has one of the highest burdens of perinatal mortality, with a higher risk among urban versus rural women. To understand the characteristics of perinatal mortality in urban health facilities, study objectives were: I. To assess the incidence of perinatal deaths in public health facilities in Dar es Salaam and classify these into a) pre-facility stillbirths (absence of fetal heart tones on admission to the study health facilities) and b) intra-facility perinatal deaths before discharge; and II. To identify determinants of perinatal deaths by comparing each of the two groups of perinatal deaths with healthy newborns.

Methods: This was a retrospective cohort study among women who gave birth in five urban, public health facilities in Dar es Salaam. I. Incidence of perinatal death in the year 2020 was calculated based on routinely collected health facility records and the Perinatal Problem Identification Database. II. An embedded case-control study was conducted within a sub-population of singletons with birthweight ≥ 2000 g (excluding newborns with congenital malformations); pre-facility stillbirths and intra-facility perinatal deaths were compared with 'healthy newborns' (Apgar score ≥ 8 at one and ≥ 9 at five minutes and discharged home alive). Descriptive and logistic regression analyses were performed to explore the determinants of deaths.

Results: A total of 37,787 births were recorded in 2020. The pre-discharge perinatal death rate was 38.3 per 1,000 total births: a stillbirth rate of 27.7 per 1,000 total births and an intra-facility neonatal death rate of 10.9 per 1,000 live births. Pre-facility stillbirths accounted for 88.4% of the stillbirths. The case-control study included 2,224 women (452 pre-facility stillbirths; 287 intra-facility perinatal deaths and 1,485 controls), 99% of whom attended antenatal clinic (75% with more than three visits). Pre-facility stillbirths were associated with low birth weight (cOR 4.40; (95% CI: 3.13-6.18) and with maternal hypertension (cOR 4.72; 95% CI: 3.30-6.76). Intra-facility perinatal deaths were associated with breech presentation (aOR 40.3; 95% CI: 8.75-185.61), complications in the second stage (aOR 20.04; 95% CI: 12.02-33.41), low birth weight (aOR 5.57; 95% CI: 2.62-11.84), cervical dilation crossing the partograph's action line (aOR 4.16; 95% CI:2.29-7.56), and hypertension during intrapartum care (aOR 2.9; 95% CI 1.03-8.14), among other factors. CONCLUSION: The perinatal death rate in the five urban hospitals was linked to gaps in the quality of antenatal and intrapartum care, in the study health facilities and in lower-level referral clinics. Urgent action is required to implement context-specific interventions and conduct implementation research to strengthen the urban referral system across the entire continuum of care from pregnancy onset to postpartum. The role of hypertensive disorders in pregnancy as a crucial determinant of perinatal deaths emphasizes the complexities of maternal-perinatal health within urban settings.