Chromosomal abnormality: Prevalence, prenatal diagnosis and associated anomalies based on a provincial‐wide birth defects monitoring system.

Aim: To investigate the epidemiology of chromosomal abnormalities (CA) in fetuses of all pregnancies based on a provincial‐wide birth defects‐monitoring system, which could provide scientific basis for making relatively policy and research. Methods: Chromosomal abnormalities cases were collected from all hospitals in Hunan Province, China, between 2016 and 2019. The prevalence of CAs was calculated to examine associations among infant sex, maternal age and region. The rates of prenatal diagnosis and termination of pregnancy (TOP) involving CA or associated anomalies were calculated as rates or proportions. Results: From 2016 to 2019, a total of 2 883 890 perinatal infants (28 weeks of gestation to postpartum 7 days) underwent prenatal screening and diagnostic tests, and 3181 fetuses were diagnosed as CA, with the prevalence of 11.03/10 000. The average prevalence of CAs was higher for male than female fetuses (11.33/10 000 vs 10.06/10 000) (OR = 1.13, 95% CI: 1.05–1.21), which was higher in urban areas than rural areas (23.03/10 000 vs 7.13/10 000) (OR = 3.23, 95% CI: 3.02–3.47), and the prevalence increased linearly with maternal age (Xtrend2 = 1821.844, P = 0.000). Among the fetuses with CAs, 3097 (97.36%) were diagnosed prenatally, and 3046 (98.35%) underwent TOP. The majority of CA were numerical abnormalities (90.18%). The main types of numerical autosomal abnormalities were trisomy 21 (6.69/10 000, 59.57%), trisomy 18 (1.13/10 000, 10.04%) and trisomy 13 (0.21/10 000, 1.88%). The main types of numerical gonosomal abnormalities were Klinefelter syndrome (0.68/10 000, 6.02%), Turner syndrome (0.49/10 000, 4.39%), Triple X syndrome (0.26/10 000, 2.29%) and 47,XYY syndrome (0.21/10 000, 1.91%). The three associated anomalies with the highest proportions were congenital heart defects (CHD) (41.06%), cleft palate or/and cleft lip (10.89%) and congenital talipes equinovarus (8.94%). Conclusion: The prevalence of CA was lower than that reported. Chromosome detection should be further promoted including test contest and coverage, especially for urban areas, older mothers and fetuses with CHD, cleft palate or/and cleft lip or congenital talipes equinovarus. [ABSTRACT FROM AUTHOR]