Epidemiologic Characteristics, Time Trend, and Seasonality of Orofacial Clefts in São Paulo State, Brazil. 2008-2019.

Objective: To characterize the epidemiology, identify trends in prevalence, seasonality, and risk factors for orofacial clefts (OFC), selecting the São Paulo state (SPS) population database.

Design: A population-based study to estimate the OFC prevalence trends in recent years, stratified by maternal age and SPS geographical clusters.

Setting: All live births (LB) with OFC in SPS from 2008-2019.

Patients: 5342 cases of OFC among 7 301 636 LB.

Interventions: Not applicable.

Main outcome measures: OFC prevalence trends, annual percent change (APC) with a 95% confidence interval, and seasonality.

Results: We found an OFC prevalence of 7.3/10 000LB in SPS, Brazil. Among all the cases, the majority were male (57.1%), Caucasian (65.4%), 77.8% born at term, 75.8% weight >2500 g, 97.1% singleton, and 63.9% of births were by cesarean section. From 2008-2019, SPS presented a stationary OFC prevalence trend; in São Paulo city, the highest APC was observed (0.05%); the maternal age group with the highest OFC prevalence rate was ≥35 years (9.2/10 000LB). We identified the existence of seasonal variation based on the conception date in the final months of the year, corresponding to the spring season (P < .001).

Conclusion: OFC had a stationary prevalence trend in recent years, with the highest prevalence in the Central North Cluster and ≥35 years maternal age group. Seasonality was observed in the spring season, and congenital malformation of lips was the most common associated pathology. This population-based study is the first to summarize the current epidemiology of OFC in SPS.