The Prevalence of Nonsyndromic Oral Clefts in Twins Compared to Singletons: The Association With Birth Weight

Purpose: To examine the prevalence of nonsyndromic oral clefts in twins compared to singletons in the United States and to evaluate the association between birth weight and nonsyndromic oral clefts. Design: A large population-based cross-sectional study was performed using the data from the US National Center for Health Statistics database in 2017. Participants: Our sample consisted of 128 310 twins and 3 723 273 singletons. Methods: The variables collected were sociodemographic variables, environmental predictors, and clinical measures. Descriptive analysis, bivariate, and multivariate logistic regression were performed. Main Outcome Measure: The main outcome variable in our study is nonsyndromic oral clefts. Results: The prevalence of nonsyndromic oral clefts was 5.22 per 10 000 in twins and 5.12 per 10 000 in singletons. Results show no significant risk of nonsyndromic oral clefts in twins compared to singletons (P = .92). There was a significant relationship between birth weight and infant diagnosed with nonsyndromic oral clefts (P = .01). Unadjusted odds ratio for birth weight was 2.52 (95% CI: 2.25-2.82). Adjusted odds for potential confounders such as mother's age, race, mother's education, gender of the infant, APGAR 5-minute score, gestational age, prenatal smoking, number of prenatal care visits, and mother's body mass index were resulted in similar but with a slightly lower odds of 2.11 (95% CI: 1.78-2.50). Conclusion: Compared to singletons, twins did not have higher risk of nonsyndromic oral clefts. Infants with low birth weight were more prone to have nonsyndromic oral clefts.