Fig 2. Unadjusted and adjusted relative risk for the association between developmental vulnerability on the Australian Early Developmental Census (AEDC) and post-birth interpregnancy intervals (IPIs).

Post-birth IPI was defined as the time between the birth of the child in the cohort and the start of pregnancy of their next youngest sibling (birth date of cohort child minus gestational age of the subsequent child, measured in completed weeks of gestation). The proportion of the study population classified as developmentally vulnerable (a) on one or more AEDC domains, and (b) on two or more AEDC domains, overlayed with the relative risk for each outcome. Developmental vulnerability was defined as scores in the bottom decile, based on the 2009 AEDC cut-offs. Adjusted model based on pooled analysis from 20 imputed datasets, controlling for; the sex of child and age of the child at the time of AEDC completion, maternal smoking status during pregnancy, preterm birth, small for gestational age, parity, maternal age at the time of child’s birth, the child speaks a language other than English at home, ethnicity of the child, preschool attendance, maternal marital status at the time of child’s birth, maternal and paternal occupation status, Accessibility and Remoteness Index of Australia category, Index of Relative Socioeconomic Disadvantage category. All data is presented with 95% confidence intervals: modified Poisson regression.