Parity, infertility, age at first birth, and risk of atrial fibrillation: data from the HUNT study

Although parity, infertility, and age at first birth are important for later development of cardiovascular disease, research on their association with atrial fibrillation (AF) is limited.

We linked data from the population-based HUNT study and the Medical Birth Registry of Norway (MBRN) and validated medical records from local hospitals. A total of 24 015 women aged 45 years or older were followed for verified incident AF. Parity and age at first birth were retrieved from the MBRN or from self-reported questionnaires in the HUNT study. A history of infertility was self-reported on the HUNT questionnaire. Cox proportional hazards models were used to calculate hazard ratios (HRs) for the multivariable-adjusted associations of parity, infertility, and age at first birth with risk of AF. During a median follow-up of 12.8 years, 1448 (6.0%) participants developed AF. Women with higher parity (four or more births vs. two births) were at 21% higher risk of AF [HR 1.21, 95% confidence interval (CI) 1.05-1.39]. A history of infertility was also associated with the risk of AF (HR 1.20, 95% CI 1.02-1.42). Among parous women, younger age at first birth (<20 vs. 20-29 years) was associated with a 20% higher risk of AF (HR 1.20, 95% CI 1.03-1.40).

Women with four or more births, or a history of infertility, or younger age at first birth have approximately a 20% higher risk of AF among women over 45 years old.