Association between interpregnancy interval and subsequent stillbirth in 58 low-income and middle-income countries: a retrospective analysis using Demographic and Health Surveys

Abstract

Background About 3 million stillbirths occur each year, 98% of which are in low-income and middle-income countries (LMICs). Interpregnancy interval is a key risk factor of interest, because it is modifiable. We aimed to investigate whether there is a causal relationship between the length of interpregnancy interval and risk of subsequent stillbirth. MethodsWe used Demographic and Health Surveys (2002-18) from 58 LMICs to study reproductive histories of women and to identify livebirths and stillbirths in the preceding 5 years. Countries were selected on the basis of the availability of interpregnancy interval data and other covariates of interest (age, education, urban or rural residence, and wealth) in surveys done since 2002. Exclusion criteria were being nulliparous, having missing parity data, and not having had at least two births (livebirth or stillbirth) in the 5 years before the survey. We combined two analytic approaches: one that analyses intervals between all births and another that analyses intervals within mothers. We report stratified estimates for the first, second, and third intervals, controlling for all past birth outcomes and intervals in a 5-year period, and other socioeconomic covariates. We also explored effect heterogeneity across key cohort subgroups.Findings Between July, 1997, and April, 2018, we identified 716 478 births from 338 223 women in 123 Demographic and Health Surveys from 58 LMICs, of which 9647 were stillbirths. Intervals of less than 6 months were associated with an increased risk of stillbirth in the between-mother models when considering the first interval (risk difference [RD] 0·0096, 95% CI 0·008-0·011). This association was slightly attenuated when considering only the second interval (RD 0·0054, 95% CI 0·0010 to 0·0099) and substantially attenuated when considering only the third interval (0·0007, -0·037 to 0·039). Within-mother modelling showed a null association with intervals of 24-59 months when considering the first and second (RD 0·007, 95% CI -0·001 to 0·016) and first and third (0·040, -0·422 to 0·501) intervals.Interpretation Although interpregnancy intervals of less than 12 months were associated with increased risk of stillbirth, these effects were attenuated when considering second and third intervals, suggesting the association in the first interval might not be causal. Future studies should use generalisable cohorts with longitudinal data, and report estimates stratified by birth order.

Beyond counting induced abortions, miscarriages and stillbirths to understanding their risk factors: analysis of the 2017 Ghana maternal health survey

“…We argue that just like miscarriages, stillbirths are also natural events and women who experience stillbirth may have been exposed to risk factors such as stress from their partners, families or struggling to meet routine deadlines at work as established in the literature [33][34][35] and these stressful events are more likely to occur in marriages. In relation to our finding that the odds of stillbirth is lower among women with higher parity, it contradicts the findings of studies that have identified that high chances of stillbirth characterise women with multiple pregnancies [39][40][41] and those that have found a u-shaped relationship between parity and stillbirths [42,43]. Notwithstanding, the possible reason for our finding could be explained in terms of pregnancy experience obtained by women with higher parity which could empower them to observe essential health practices that protect them from stillbirths.…”

Characteristics and Adverse Outcomes of Chinese Adolescent Pregnancy Between 2012 and 2019: An Observational Study of 438 Health Facilities

“…They do not have the ability to live independently, and they are not physically or psychologically ready for pregnancy. Premature pregnancy has adverse effects on health 1,2,[6][7][8]10,11,19,22,[28][29][30] . Our study demonstrated that higher risks of eclampsia, severe anaemia, and MNM were observed at a gestational age greater than 37 weeks among adolescent mothers compared with mothers aged 20-24 years.…”

“…Perinatal outcomes were restricted to live births at 28 gestational weeks or later or to a birthweight of more than 1000 grams, in accordance with the de nition of third-trimester stillbirth from the WHO 19 . Gestational age in China is generally ascertained on the basis of the last menstrual period or the ultrasound examination when the date of the last menstrual period is not known 20 .…”

Interpregnancy interval and pregnancy loss in a rural South Africa: A population-based cohort study

“…We defined the IPI as the time between the end of one pregnancy and the start of the next pregnancy (Swaminathan et al ., 2020). This was established by reviewing the AHRI pregnancy registry and calculating the time in months between the date that the first pregnancy ended and the date of the last menses associated with the start of the second pregnancy.…”

“…Given these implications, and the projected exponential growth of the SSA population in the next few decades (Ezeh et al ., 2020), interest in understanding modifiable risk factors for pregnancy loss in this region has gained momentum. The interpregnancy interval (IPI), or the period of time between the end of one pregnancy and the start of the next pregnancy (Swaminathan et al ., 2020), is perhaps one of the least understood modifiable risk factors for pregnancy loss.…”