Impact of the COVID-19 pandemic on the monthly proportion of male births and spontaneous fetal death rates in Japan: a descriptive epidemiological study using national vital statistics

Abnormal increases in spontaneous fetal deaths could not explain male birth proportion decreases. Abnormal decreases in proportion of male births occurred approximately 8-10 months after Japan's state of emergency declarations, but not 8-10 months after stimulus payments among groups with targeted families. Financial support might therefore have prevented decreases in the proportion of male births during states of emergency, but analytical studies are needed to test this hypothesis.