Age at first birth and risk of later-life cardiovascular disease: a systematic review of the literature, its limitation, and recommendations for future research

Abstract

BackgroundCardiovascular disease (CVD) is the principal contributor to the burden of disease and mortality worldwide. Previous studies observed associations between early age at first birth (AFB) and all-cause mortality. AFB may be associated with CVD both through physiological and sociobiological pathways. In this paper, we review the literature on AFB and CVD events and mortality. Additionally, we provide an overview of limitations of the current research and recommendations for future research.MethodsPubMed and Web of Science databases were searched for observational studies published between 1980-June 2016, investigating associations between AFB and CVD events and mortality. Data were extracted using a pre-defined list.ResultsA total of 20 publications, reporting on 33 associations, were included in the review. Ten studies observed a positive association between early AFB and CVD while two studies observed a positive association between later AFB and CVD. Substantial methodological limitations were observed related to: operationalization of exposure categories, choice of reference category, sample size, follow-up time and possibly over adjustment.ConclusionsEarly AFB is possibly related to CVD. More work, in particular from large cohort studies starting before reproductive age is reached, is needed to better investigate this relationship, and to ascertain causal pathways that may explain observed associations.Electronic supplementary materialThe online version of this article (doi:10.1186/s12889-017-4519-x) contains supplementary material, which is available to authorized users.

Adolescent Childbirth Is Associated With Greater Framingham Risk Scores for Cardiovascular Disease Among Participants of the IMIAS (International Mobility in Aging Study)

“…Finally, we recently conducted a systematic review on AFB and CVD events and mortality. The study findings were relatively consistent when young AFB was defined as 20 years or younger and pointed towards increased risk for CVD for women with a young AFB …”

“…We operationalized AFB into 5 categories: <20 years, 20 to 24 years, 25 to 29 years, ≥30 years, and nulliparous women. Most studies examining AFB and CVD events have defined their youngest age group as <20 years . Because we hypothesize that younger AFB is associated with greater CVD risk, we treated AFB <20 years as the reference group.…”

“…Numerous studies observe associations between an early AFB, especially adolescent childbirth, and all‐cause mortality and a few observe associations between AFB and CVD risk factors, CVD events, and CVD mortality . Parity has been examined more thoroughly than AFB, including as part of 2 systematic reviews on women's cardiovascular health .…”

“…In those studies reporting statistically significant associations, typically nulliparous and multiparous women are at greater risk of CVD . Yet, AFB may confound observed associations between parity and CVD, because AFB is closely linked with parity . Women with early AFB tend to have more children .…”

“…Numerous studies observe associations between an early AFB, especially adolescent childbirth, and all-cause mortality, [11][12][13][14] and a few observe associations between AFB and CVD risk factors, CVD events, and CVD mortality. 6,[15][16][17][18] Parity has been examined more thoroughly than AFB, 2,4,[19][20][21][22] including as part of 2 systematic reviews on women's cardiovascular health. 4,19 In those studies reporting statistically significant associations, typically nulliparous and multiparous women are at greater risk of CVD.…”