Do short birth intervals have long term implications for the health of parents? Results from analyses of complete cohort Norwegian register data

Emily Grundy, London School of Economics and Political Science (LSE)
Øystein Kravdal, University of Oslo

Short inter-pregnancy intervals are associated with poorer birth outcomes and child survival and WHO recommends an interval of 24 months or more from a live birth to the start of the next pregnancy. Inter-pregnancy or inter-birth intervals have also been associated with maternal outcomes, but results have been disputed. Nearly all studies of associations between inter-birth intervals and parental health have considered only short term effects on mothers. However, stresses arising from depleted nutrition or from strains associated with raising two young children close in age might be hypothesised to also have longer term effects on parental health and such effects have been suggested in two recent UK studies. We investigate associations between inter-birth intervals and mortality risks in late middle age using high quality register data for the whole Norwegian population. We also investigate associations with prescription drug use, as an indicator of morbidity. We focussed on parents of two-four children and controlled for age, year of observation, education, age at first birth, parity and, in some models, whether or not there had been a change in co-parent since the previous birth. Results indicate adverse effects of birth intervals of less than 18 months and, to a lesser extent, intervals of 18-23 months on mortality risks of both mothers and fathers. Mothers of twins also had raised mortality risks and higher prescription drug use. The lack of gender differentiation (except for parents of twins)suggests the operation of biosocial pathways which, together with possible confounding via various selective influences we have been unable to control for, need further investigation.