OBJECTIVES: Women are frailer than men across different populations and age groups. However, the mechanisms are still not fully understood. One possible cause is pregnancy and motherhood. The objective of this study was to examine trajectories of Frailty Index over time according to the number of pregnancies. DESIGN: A prospective study with repeated measures over 14 years. SETTING AND PARTICIPANTS: A total of 2060 community-dwelling older women aged ≥60 years in England. METHODS: The number of pregnancies was calculated as a sum of the number of live births and the number of miscarriages, still-births, or abortions. The Frailty Index (FI) was constructed using 60 deficits and repeatedly calculated every 2 years over 14 years. Trajectories of FI according to the number of pregnancies were estimated by a mixed effects model. RESULTS: Mean FI was 0.15 at baseline. A mixed effects model adjusted for age, smoking, alcohol use, education, and wealth showed that FI increased over time. A higher number of pregnancies were significantly associated with a higher FI (estimate = 0.0047, 95% confidence interval = 0.0020, 0.0074). CONCLUSIONS AND IMPLICATIONS: The current study showed that a higher number of pregnancies were significantly associated with a higher degree of frailty at baseline and over time. Pregnancy and child rearing may explain some of the observed excess risk of frailty in women. Pregnancy-related factors, such as pregnancy loss, types of delivery, length of pregnancy, childbearing, and child rearing, should be examined in relation to frailty in future studies
