Beyond birth outcomes: Interpregnancy interval and injury‐related infant mortality

Abstract

Background Several studies have examined the association between IPI and birth outcomes, but few have explored the association between interpregnancy interval (IPI) and postnatal outcomes. Objective We examined the association between IPI and injury‐related infant mortality, a leading cause of postneonatal mortality. Methods We used 2011‐2015 US period‐linked birth‐infant death vital statistics data to generate a multiyear birth cohort of non‐first‐born singleton births (N = 9 782 029). IPI was defined as the number of months between a live birth and the start of the pregnancy leading to the next live birth. Causes of death in the first year of life were identified using ICD‐10 codes. Hazard ratios (HR) for IPI categories were estimated using Cox proportional hazards models adjusted for birth order, county poverty level, and maternal characteristics (marital status, race/ethnicity, education, age at previous birth). Results After adjustment, overall infant mortality (48.1 per 10 000 births) was higher for short and long IPIs compared with IPI 18‐23 months (reference): <6, aHR 1.61, 95% CI 1.54, 1.68; 6‐11, aHR 1.22, 95% CI 1.17, 1.26; and 60+ months, aHR 1.12, 95% CI 1.08, 1.16. In comparison, the risk of injury‐related infant mortality (4.4 per 10 000 births) decreased with longer IPIs: <6, aHR 1.77, 95% CI 1.55, 2.01; 6‐11, aHR 1.41, 95% CI 1.25, 1.59; 12‐17, aHR 1.25, 95% CI 1.10, 1.41; 24‐59, aHR 0.78, 95% CI 0.69, 0.87; and 60+ months, aHR 0.55, 95% CI 0.48, 0.62. Conclusion Unlike overall infant mortality, injury‐related infant mortality decreased with IPI length. While injury‐related deaths are rare, these patterns suggest that the timing between births may be a marker of risk for fatal infant injuries. The first year postpartum may be an ideal time for the delivery of evidence‐based injury prevention programmes as well as family planning services.

Sudden Unexpected Infant Death

“…Generally, there is a high incidence of low birth weight and prematurity among infants in the Middle East (Hamadneh et al 2016a). Of particular relevance to Middle Eastern women are short inter-pregnancy intervals, inadequate prenatal care, and nutrition; adolescent pregnancy, low socio-economic status, and low education levels are risk factors for the aforementioned outcomes (Thoma et al 2019).…”

Interpregnancy interval and outcomes beyond the neonatal period: More complicated than it seems

“…Barber and East analysed data from the US National Longitudinal Survey of Youth and noted that while the home environment, on average, declined following the birth of a sibling, the decline was greater when the birth was unintended than when it was intended, even at comparable interval . This report provides a possible explanatory mechanism for the results of Thoma et al…”

“…In this issue of Paediatric and Perinatal Epidemiology , Thoma and colleagues evaluated the association between interpregnancy (livebirth to subsequent conception) interval (IPI) and infant mortality, focusing particularly on injury‐related and general external cause mortality. Short intervals were associated with elevated risk of all types of mortality, although associations with long (60 months or longer) intervals differed by timing and cause.…”

Exploring the Factors Associated with Infant Mortality in Rural Indonesia

“…The first birth order had higher odds of infant mortality since the mothers had no experience taking care of their first child. Thus, the first child had a higher chance of dying from preventable injuries (Thoma et al, 2019). However, the last birth order with a high number of births can reduce the chances of survival of the baby because maternal fatigue decreases the mother's ability to concentrate (Iwata et al, 2018), which can increase the incidence of postpartum fatigue (Thomas & Spieker, 2016), feeling tight Senol et al, 2019), and caused their babies to wean their breast milk earlier (Fata & Atan, 2018).…”