Pregnancy complications, along with several other factors, including starting periods early, the use of combined oral contraceptives and early menopause are linked to a heightened risk of heart disease and stroke in later life, according to new analysis of data by a team of researchers at the Universities of Birmingham and Warwick and Queen Mary’s University London, published in the BMJ.
Bringing together the results of 32 studies, which evaluated a range of risk factors over an average follow up period of seven to ten years, researchers found several factors related to fertility and pregnancy that seem to be associated with subsequent cardiovascular disease, including use of combined oral contraceptives, polycystic ovary syndrome, pre-eclampsia, miscarriage and early menopause.
Women with pre-eclampsia in particular were four times more at risk of heart failure in later life. On the contrary, a longer time spent breastfeeding was associated with a reduced risk of cardiovascular disease.
Possible explanations for these associations include family medical history, genetics, weight, high blood pressure and cholesterol levels, and chemical imbalances from use of hormonal contraceptives. However, no association was found between cardiovascular disease outcomes and current use of progesterone only contraceptives, use of non-oral hormonal contraceptive agents, or fertility treatment.
The researchers point to some limitations, such as missing data and the fact that reviews were largely based on observational evidence, so they cannot rule out the possibility that other unmeasured (confounding) factors may have had an effect.
Nevertheless, they say the evidence reported in this umbrella review suggests that, from menarche to menopause, the reproductive profile of women is associated with their future risk of cardiovascular disease.
It also provides clarity on the quality of the evidence, identifies gaps in evidence and practice, and provides recommendations that could be incorporated into guidelines, such as incorporating reproductive risk factors as part of the risk assessment for cardiovascular disease.
Lead author, Kelvin Okoth, from the University of Birmingham’s Institute of Applied Health Research, said: “From menarche to menopause, female reproductive risk factors, including adverse pregnancy outcomes and fertility-related or hormonal risk factors, are associated with risk of cardiovascular disease in later life.”
Corresponding and joint senior author, Dr Krishnarajah Nirantharakumar, added: “The strongest associations for cardiovascular outcomes - up to a 2-fold increase in risk - were found among women with a history of pre-eclampsia, recurrent pre-eclampsia, gestational diabetes mellitus, stillbirth or pre-term birth. The association for heart failure was 4-fold among women with a history pre-eclampsia.”
Senior author, Dr Nicola Adderley, noted: “Many of these reproductive risk factors are not mentioned in current UK guidelines. Identification of reproductive risk factors at an early stage in the life course of women might facilitate the initiation of strategies to modify potential risks. Policy makers should consider incorporating reproductive risk factors as part of the assessment of cardiovascular risk in clinical guidelines.”