Childbearing may reduce mortality in later life

Jul 9 2012

By Sarah Guy

All-cause mortality rates fall progressively among women aged 60-76 years the more children they have borne, show Australian study results.

The findings indicate that all-cause mortality is highest among nulliparous women in this age group, and lowest among women with three children or more.

"This finding will have underlying mechanisms which deserve further elucidation, potentially adding to the quality of maternal health," write Leon Simons, from the University of New South Wales in Sydney, and colleagues, in Age and Ageing.

The trend can be pinpointed to a reduction in the risk for death from cancer and respiratory conditions with increasing parity, although the team was unable to identify exactly which specific conditions were responsible.

Simons and co-workers monitored hospital and death records in a cohort of 1572 women aged 60 years in 1988, over a 16-year period, until 2004. Participants' baseline variables (including age, cigarette smoking, body mass index [BMI], self-rated health, and diabetes) and the number of children they had produced were noted.

All-cause mortality fell with increasing parity, with the highest rates observed in women with no children (n=140), at 51.2%, dropping to 47.1% in women with one child (n=159), 34.1% in women with two children (n=322), and 31.3% in women with three children (n=361), at which point, rates leveled off.

After adjusting these figures for significant potential confounders not including BMI, hypertension, or diabetes - all factors that showed an upward trend with increasing parity in unadjusted analysis - the hazard ratios (HRs) for mortality fell progressively with increasing parity. They became significant in women with six or more children, who were 40% less at risk for death than their nulliparous counterparts.

The team reports that coronary heart disease (CHD) was "generally increased" in all parous women, ranging from 60 to 111% higher than their nulliparous peers.

Including BMI, hypertension, and diabetes in the multivariate analysis had no significant effect on results, say Simons et al.

"Notably absent was any clear association between parity and self-rated health, physical disability or depression score," they write. "This suggests that surviving women with a mean age around 70 years are not carrying excess morbidity from earlier childbearing."

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