The association between parity, CVD mortality and CVD risk factors among Norwegian women and men

Several studies have shown that women and men with two children have lower mortality than the childless, but there is less certainty about mortality, including CVD mortality, at higher parities and meagre knowledge about factors underlying the parity-mortality relationship.

The association between parity and CVD mortality was analyzed by estimating discrete-time hazard models for women and men aged 40-80 in 1975-2015. Register data covering the entire Norwegian population were used, and the models included a larger number of relevant sociodemographic control variables than in many previous studies. To analyze the relationship between parity and seven CVD risk factors, logistic models including the same variables as the mortality models were estimated from the CONOR collection of health surveys, linked to the register data.

Men (but not women) who had four or more children had higher mortality from CVD than those with two, although this excess mortality was not observed for the heart disease sub-group. Overweight, possibly in part a result of less physical activity, seems to play a role in this. All CVD risk factors except smoking and alcohol may contribute to the relatively high CVD mortality among childless.

Childbearing is related to a number of well-known CVD risk factors, and becoming a parent or having an additional child is, on the whole, associated with lower-or at least not higher-CVD mortality in Norway. However, for men family sizes beyond three children are associated with increased CVD mortality, with risks of overweight one possible pathway.