Impact of age at first childbirth on primary open-angle glaucoma.

OBJECTIVE: No studies have addressed the relationship between the timing of first childbirth and primary open-angle glaucoma (POAG). The aim of the study was to identify the relationship between age at first childbirth and POAG and to examine the contribution of parity to the age at first childbirth-POAG relationship in postmenopausal women.

METHODS: The study population comprised postmenopausal women aged 50 or above in the cross-sectional Korea National Health and Nutrition Examination Survey from 2010 to 2012. Participants were grouped into quintiles by age at first childbirth for analysis. This study used logistic regression and mediation analyses with accommodations for the complex sampling structure of the survey.

RESULTS: Of the 4,057 women in the study population, the mean age at first childbirth was 23.7 years, and POAG prevalence was 3.4%. Prevalence of POAG was lowest in women whose first childbirth was between the ages of 27 and 44 (1.8%). Their risk for POAG (odds ratio [OR], 0.25; 95% CI, 0.10-0.65) was significantly lower than in those whose first childbirth was between the ages of 13 and 20, after adjustments for covariates. Late first delivery (≥27 y) was directly (OR, 0.57) and totally (OR, 0.85) associated with the decreased risk of POAG; decreased parity in women who delivered their first child at an older age attenuated the age at first childbirth-POAG relationship (OR of indirect effect, 1.50).

CONCLUSIONS: First childbirth at the age of 27 years or above decreases the risk of POAG in postmenopausal women. Decreased parity, caused by late first childbirth, attenuated the magnitude of the total effects of age at first childbirth on POAG.