A woman's reproductive success: Long-term implications for chronic diseases and death

Loss of children, stillbirths or live births that die later, has been related to long term maternal health. It is unclear whether grief or pre-existing health conditions are the strongest causal factors. In our last article, we have studied these relations in relation to perinatal death (stillbirth or children dying in the first week of life), again, we focus on a woman's overall reproduction, not just the first birth which seems to be the most common strategy. A normal response after a loss will be to replace the loss with a new pregnancy, and our data confirm that fertility increases after a loss, relatively women who have surviving children. This response we see regardless of parity (number of previous children). Studies show that a 'replacement child' reduces grief relatively the lost child. In our study, we find a strong relationship between one (or more) losses and long term health of the mother (considered again as an increased risk of death - all causes, or death due to cardiovascular disease), but not for all women with losses. We find particularly increased risk (5-fold) for women who lose their first child, or who loses the first two children, and later do not have more children. By far the majority of women who have losses have more children, and especially if these additional pregnancies are in time after the loss, we see little or no increased risk of increased mortality for the mothers. This applies particularly to mothers with high education. Both for a better understanding of the relations between pregnancy outcome and long-term health of the mother, and for the prevention of cardiovascular disease, these clear heterogeneities in risks are of huge importance.

Pregnancy problems like preeclampsia, gestational diabetes and preterm birth have long been studied in relation to the infant's health. Studies have begun to consider how such problems might influence the mother's long-term mortality. Women die at younger ages if they: delivered preterm, developed preeclampsia or the child had low birth weight. Observations are typically based on studies of the 1st pregnancy which leads to invalid conclusions: adverse pregnancy outcomes may impede a 2nd pregnancy, and wom en with one pregnancy have higher mortality than women with more pregnancies. We will study long-term maternal health in relation to complete pregnancy histories utilising the Medical Birth Registry of Norway - one of the few settings in the world where t his is available. This unique source of population-based data covers 1967-2009, with 2.5 mill births in 1.2 mill sibships, linked to death- and education-registries. Preliminary analyses suggest that long-term mortality is better predicted by the mother's total reproductive experience and that the association of preeclampsia in the first pregnancy with maternal cardiovascular disease disappears in mothers who continue with healthy pregnancies. Focus will be on preeclampsia, preterm birth, perinatal death, birth defects, and fetal growth. We will study variation in total maternal mortality, deaths due to cardiovascular causes, site-specific cancers and stroke, contrast the results with paternal survival, and evaluate effect differences between social strat a (maternal education). Pregnancy outcomes and long-term maternal mortality risk have never before been addressed based on the woman?s complete reproductive history. The project will fundamentally change how physicians interpret the effects of adverse pre gnancy outcomes on mother?s future health and may also lead to new opportunities for diagnosis and prevention of latent maternal diseases that are expressed first as pregnancy failure.