The effect of inter-pregnancy interval on stillbirth in urban South Ethiopia

1. Inter-pregnancy interval under 18 months increased the risk of stillbirth in a population of pregnant women in urban South Ethiopia.

Evidence Rating Level: 2 (Good)

This study defines stillbirth as a baby born with no signs of life (heartbeat or spontaneous breathing) at or after 28 weeks gestation or a baby weight at birth >1000 g. Stillbirth can occur either before giving birth (macerated) or during labour (fresh) and has profound and long-lasting medical, psychological, economic, and social impacts on mothers and their families. Globally, approximately 2 million stillbirths occur each year. Of these, 84% occur in low- and middle-income countries and Sub-Saharan Africa alone has a stillbirth rate ~7 times that of developed countries (21.7 vs. 3.1 per 1000 births). Ethiopia has a stillbirth rate of 24.6 per 1000 births and it remains a poorly understood adverse outcome of pregnancy and a significant clinical challenge. Furthermore, when stillbirth occurs during the first pregnancy, the marriage is presumed to be unlucky, increasing anxiety and depression during subsequent pregnancies and causing considerable strain on marital, familial, and cultural relationships. Inter-pregnancy interval (IPI) is defined as time elapsed from live birth to subsequent conception or a woman’s last menstrual period. Both shorter (<6, <18, <24 months) and longer (>59 months) IPIs have been found to be associated with increased risk of prematurity, low birth weight, and small for gestational age. The relationship between IPI and stillbirth is poorly understood. Consequently, this prospective cohort study explores the effect of IPI on stillbirth in urban South Ethiopia. A total of 2578 pregnant women were enrolled and followed until delivery. Exposed groups included pregnant women with IPIs of <18 months and 18-23 months. Unexposed groups included pregnant women with IPIs of 24-60 months. The outcome variable was stillbirth (both macerated and fresh). It was found that the risk of stillbirth was nearly four times higher for women with IPI of <18 months as compared to 24-60 months (ARR = 3.55, 95% CI: 1.64, 7.68). Interventions targeting factors contributing to shorter IPIs may help in reducing the risk of stillbirth.

Click here to read the study in BMC Medicine

Relevant Reading: Magnitude and trend of perinatal mortality and its relationship with inter-pregnancy interval in Ethiopia: A systematic review and meta-analysis

In-Depth [Prospective Cohort Study]: This study was conducted among pregnant women in five urban settings in South Ethiopia. Participants were recruited and enrolled by trained midwives during house visits organized between July 8, 2019 and March 30, 2020. Inclusion criteria were women who were pregnant at the time of recruitment, had a live birth during the most recent childbirth, and were able to recall the date of their last childbirth. The exposure variable was inter-pregnancy interval (IPI), which was ascertained by subtracting the date of the most recent childbirth from the date of the last menstrual period. Women with IPIs of <18 months and 18-23 months were categorized as exposed groups. Women with IPIs of 24-60 months were categorized as an unexposed group. The outcome variable was both macerated and fresh stillbirths, which was ascertained during labour and delivery. A generalized linear model for binary outcome was applied. Relative risk was used to estimate the effect size with a 95% confidence level. Attributable fraction and population attributable fraction were used to report the public health impact of exposure. The overall incidence of stillbirth was 15 per 1000 total births (95% CI: 11, 20%). The incidence varied across IPI: Among women with an IPI of <18 months, the incidence of stillbirth was 30 per 1000 total births, among those with an IPI of 18-23 months, the incidence was 8 per 1000 total births, and among those with an IPI of 24-60 months, the incidence was 10 per 1000 total births. The risk of stillbirth was found to be nearly four times higher for women with IPIs of <18 months as compared to 24-60 months (ARR = 3.55, 95% CI: 1.64, 7.68). Consequently, approximately 72% (AF = 72, 95% CI: 39, 87%) of stillbirth among the IPI of <18 months category and 42% (PAF = 42, 95% CI: 23, 50%) of stillbirth in the study population were attributed to an IPI of <18 months. Interventions that prevent IPIs of <18 months, such as improving contraception utilization, may help reduce the risk of stillbirth. Further research on stillbirth rate is needed.

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