The Risk of Perinatal Mortality Following Short Inter-Pregnancy Intervals: Insights from 109 Demographic and Health Surveys

Background: Inter-pregnancy interval (IPI), or the time from birth or termination of a pregnancy to next conception, has been identified as a potentially modifiable risk factor to improve perinatal outcomes. While the evidence supports WHO recommendation on interval from birth to next conception, there are still conflicting results regarding its recommendation of waiting for at least six months after a pregnancy loss to improve subsequent pregnancy outcomes. We examine the risk of perinatal mortality following short IPIs, stratified by outcome of the last pregnancy.Methods: We extracted data for pregnancies with gestational age and pregnancy outcomes from all Demographic and Health Surveys conducted since 2000 that included reproductive/contraceptive calendar module. The primary outcome is perinatal mortality (stillbirth and early neonatal death) while IPI is our exposure of interest, grouped into categories of <6, 6-11, 12-17, 18-23, and 24-59 months. The analysis was stratified by preceding pregnancy outcome (live births; stillbirths; and abortions). Kaplan-Meier method and Cox Proportional Hazard model were used to calculate the cumulative probability of perinatal mortality and the hazard ratios, respectively. Meta-analysis with random effect was used to pool country-specific hazard ratios.Findings: The analysis sample comprised of 680,243 pregnancies in 109 surveys from 46 countries. The pooled hazard ratio of perinatal death was 2.72 (95% CI 2.52-2.94) times higher for an IPI of less than 6 months compared to the recommended optimal waiting time of 18-23 months following a livebirth. Hazard ratios followed a context-related pattern, with the highest value (2.95) in sub-Saharan Africa and the lowest in North Africa, West Asia and Europe (1.98). IPI of less than 3, 6, and 12 months following stillbirth or abortion (spontaneous or induced) does not pose a risk for perinatal death in subsequent birth.Interpretation: Our study reaffirms the WHO recommendation on optimal interval between the last live birth and the next pregnancy of at least 24 months and avoiding pregnancy before 18 months. However, contrary to WHO recommendation, no benefit was evident in delaying the next pregnancy after a pregnancy loss. In low- and middle-income countries (LMICs) that account for most of the perinatal deaths, a majority of these deaths can be averted through optimal birth spacing by contraceptive use. Women with a foetal loss should not be advised to delay attempting the next pregnancy for six month, but try when they feel ready.Funding: No funding was received for this projectDeclaration of Interest: We declare no competing interests.