Interpregnancy intervals and child development at age 5: a population data linkage study

Abstract

Objective: To investigate the associations between interpregnancy intervals (IPIs) and developmental vulnerability in children's first year of full-time school (age 5).

Design: Retrospective cohort study using logistic regression. ORs were estimated for associations with IPIs with adjustment for child, parent and community sociodemographic variables.

Setting: Western Australia (WA), 2002-2015.

Participants: 34 574 WA born singletons with a 2009, 2012 or 2015 Australian Early Development Census (AEDC) record.

Main outcome measure: The AEDC measures child development across five domains; Physical Health and Wellbeing, Social Competence, Emotional Maturity, Language and Cognitive Skills (school-based) and Communication Skills and General Knowledge. Children with scores <10th percentile were classified as developmentally vulnerable on, one or more domains (DV1), or two or more domains (DV2).

Results: 22.8% and 11.5% of children were classified as DV1 and DV2, respectively. In the adjusted models (relative to the reference category, IPIs of 18-23 months), IPIs of <6 months were associated with an increased risk of children being classified as DV1 (adjusted OR (aOR) 1.17, 95% CI 1.08 to 1.34), DV2 (aOR 1.31, 95% CI 1.10 to 1.54) and an increased risk of developmental vulnerability for the domains of Physical Health and Wellbeing (aOR 1.25, 95% CI 1.06 to 1.48) and Emotional Maturity (aOR 1.36, 95% CI 1.12 to 1.66). All IPIs longer than the reference category were associated with and increased risk of children being classified as DV1 and DV2 (aOR >1.15). IPIs of 60-119 months and ≥120 months, were associated with an increased risk of developmental vulnerability on each of the five AEDC domains, with greater odds for each domain for the longer IPI category.

Conclusions: IPIs showed independent J-shaped relationships with developmental vulnerability, with short (<6 months) and longer (≥24 months) associated with increased risks of developmental vulnerability.

Keywords: community child health; epidemiology; public health.

Figure 1

Eligible cohort and numbers included for analyses. AEDC, Australian Early Development Census; IPIs, Interpregnancy Intervals; WARDA, Western Australian Register of Developmental Anomalies.

Figure 2

Unadjusted and adjusted ORs for the association between interpregnancy intervals (IPIs) and developmental vulnerability on Australian Early Development Census (AEDC) domains. ORs relative to the IPI interval reference category of 18–23 months between IPI and (A) developmental vulnerability on one or more AEDC domains (DV1) and (B) developmental vulnerability on two or more AEDC domains (DV2). Adjusted for maternal smoking status during pregnancy, mode of delivery, preterm birth, small for gestational age, parity, mother’s age at time of child’s birth, sex of child, ethnicity, child speaks a language other than English at home, age of child at time of AEDC completion, number of siblings, mother’s marital status at time of child’s birth, father’s and mother’s occupational status scale at time of child’s birth, Accessibility and Remoteness Index of Australia and Index of Relative Socioeconomic Disadvantage category. All data is presented as ORs and 95% CIs; logistic regression (n=34 574).