Differences in prenatal diagnosis rate of congenital anomalies associated with singletons and multiple births: An observational study of more than 1.9 million births in Zhejiang Province, eastern China, during 2012-2018.

OBJECTIVE: To characterize differences in the prenatal detection of congenital anomalies (CAs) associated with singleton and multiple births. METHODS: This observational study covered all births registered in the CA surveillance system in Zhejiang Province of China during 2012-2018. Differences in the incidence and characteristics between singletons and multiple births with CAs were tested. Multivariate logistic regression models were performed to explore the associations of prenatal detection rate of CAs with multiple births. RESULTS: Totals of 49 872 singletons and 3324 multiple births with CAs were analyzed. The mean incidences of CA for single and multiple births were 27.12 and 54.42 per 1000 births, respectively. After adjustment for covariates, CAs associated with multiple births were less likely to be diagnosed prenatally (adjusted odds ratio [OR] 0.38, 95% confidence interval [CI] 0.34-0.43), as were congenital heart defects, congenital hydrocephalus, cleft lip with cleft palate, cleft lip without cleft palate, limb reduction defects, congenital diaphragmatic hernia, trisomy 21 syndrome, congenital malformation of the urinary system, and other chromosomal malformation, compared with singletons with CAs. CONCLUSION: Multiple birth is associated with a significantly higher risk of CA, but a significantly lower prenatal diagnosis rate. Therefore, the healthcare of women with multiple pregnancy and their fetuses should be strengthened.