The fertility-inhibiting effect of mosquitoes: Socio-economic differences in response to the Zika crisis in Colombia

We estimated the impact of the Zika virus outbreak on birth rates and demand for health care services in Colombia. Our analysis exploits the variation in the level of natural protection against mosquito-transmitted diseases across the country. This characteristic induced exogenous variation in Zika incidence, which allows us to construct a control group of municipalities with similar historical fertility trends but with differential exposure to the Zika crisis. We implemented a difference-in-differences model after matching, as well as synthetic control. We found a decrease in birth rates of approx. 10% in the last two quarters of 2019. The impact of the virus was similar irrespective of the women’s education level, and we found no discernible impact on teenage pregnancy.