Exploring the Zika virus epidemic’s association with fertility in a cohort of women of Northeastern Brazil: socioeconomic and educational gradients

Objective: To explore the association between the Zika virus epidemic, fertility rates, and sociodemographic and behavioral factors influencing birth trends. Methods: A prospective cohort of 1,497 women aged between 15 and 39 years living in arbovirus-endemic areas in Fortaleza, Brazil, was analyzed. Women were enrolled in February 2018 and followed up two times every six months. The total fertility rate (TFR), age-specific fertility rate (ASFR), and mean age at first birth (MAB) were estimated and a multivariate Poisson regression model was used to explore the main factors associated with fertility. Results: The TFR was lowest during the epidemic period (2.64, 95%CI 2.06–3.06), increasing in the post-epidemic phase (TFR=3.52, 95%CI 3.18–3.86). Low educational attainment (RR=1.32, TFR=3.69, 95%CI 3.26–4.13), overcrowding (RR=1.27, TFR=3.26, 95%CI 2.98–3.54), and having undergone an abortion (RR=1.85, TFR=4.88, 95%CI 4.31–5.45) were associated with higher fertility rates. Conversely, having had an unwanted pregnancy was associated with reduced fertility (RR=0.81, TFR=2.65, 95%CI 2.41–2.89). Conclusion: We observed a slowdown in fertility rates during the epidemic period coincident with human Zika virus transmission with large differences by sociodemographic gradients.