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

BACKGROUND Previous studies observe associations between lifetime parity and cardiovascular disease, but relatively fewer investigate age at first childbirth (AFB). Herein, we examine the association of AFB with a summary cardiovascular risk measure (Framingham Risk Score [FRS]). METHODS AND RESULTS As part of the IMIAS (International Mobility in Aging Study), data were collected in 2012 among 1047 women, aged 65 to 74 years, from Canada, Albania, Colombia, and Brazil. FRSs were calculated to describe cardiovascular risk profiles, and linear regression analyses were performed, adjusting for early life and socioeconomic variables. Women with an AFB of <20 years were compared with women with an AFB of 20 to 24, 25 to 29, and ≥30 years, as well as nulliparous women. We also compared FRS between combinations of AFB and parity categories: nulliparous women, parity 1 to 3 combined with AFB <20 years, parity ≥4 with AFB <20 years, parity 1 to 3 with AFB ≥20 years, and parity ≥4 with AFB ≥20 years. Women with an AFB of <20 years had a higher mean FRS compared with all other AFB groups. Compared with the lowest AFB risk group (25-29 years), women with an AFB of <20 years had a 5.8-point higher mean FRS (95% confidence interval, 3.4-8.3 points). Nulliparous women presented the lowest mean FRS in all analyses. The analysis comparing combinations of AFB and parity categories showed no meaningful differences in FRS between women who had 1 to 3 childbirths and those who had ≥4 childbirths within the stratum of AFB <20 years, and in the stratum of AFB ≥20 years. CONCLUSIONS Our analyses suggest that nulliparity and AFB, rather than increasing parity, drive the association with cardiovascular disease risk.