Incidence of birth defects in Hunan Province, China: an in-depth cross-analysis according to gender, residence, and maternal age

Abstract

Objective There is some evidence that birth defects are related to maternal age, gender, and residence, but in-depth studies need to be included. To define the relationships between gender, residence, maternal age, and a broad range of birth defects, we examined surveillance data from the Birth Defects Surveillance System in Hunan Province.Methods Data were obtained from the Birth Defects Surveillance System in Hunan Province, China, 2010–2020. Incidences of birth defects (number of cases per 10000 fetuses (births and deaths at 28 weeks of gestation and beyond)) with 95% confidence intervals (CI) were calculated by residence, gender, maternal age, year, and 23 specific defects. Crude odds ratios (ORs) were calculated to examine the association of each maternal characteristic with birth defects.Results Our study included 1619376 fetuses, and 30596 fetuses had at least one birth defect diagnosis. The incidence of birth defects was 188.94/10000 (95%CI: 186.82-191.05). Birth defects were more frequent in males than females (210.46 vs. 163.03/10000, OR = 1.30, 95%CI: 1.27–1.33), in urban areas than rural areas (223.61 vs. 162.90/10000, OR = 1.38, 95%CI: 1.35–1.41), and in mothers ≥ 35 years old compared to mothers 25–29 years old (206.35 vs. 187.79/10000, OR = 1.10, 95%CI: 1.06–1.14). Cleft palates were more frequent in males, and nine specific defects were more frequent in females. Five specific defects were more frequent in rural areas, and eight were more frequent in urban areas. Compared to mothers 25–29 years old, five specific defects were more frequent in mothers < 20 years old, seven specific defects had higher incidences in mothers 20–24 years old, two specific defects had higher incidences in mothers 30–34 years old, and ten specific defects had higher incidences in mothers ≥ 35 years old.Conclusion Our data indicate that gender, residence, and maternal age differences in the incidences of birth defects and most specific defects are common. Several mechanisms have been proposed to explain these differences. Our study is of great significance for researchers attempting to identify novel risk factors for birth defects.