Recent Trends in the Birth Prevalence of Cleft Lip With or Without Cleft Palate in the Tokai Region of Japan: Possible Association With Changes in the Prenatal Diagnostic Environment

ABSTRACT

This study investigated long‐term trends in the birth prevalence of cleft lip and/or cleft palate (CL/P) in central Japan and examined whether recent developments in prenatal diagnosis may be related to these trends. Annual questionnaire surveys were conducted for 42 years across maternity facilities in the prefectures of Aichi, Gifu, and Mie. Cases were categorized as cleft lip with or without cleft palate (CL ± P) or cleft palate only (CPO). Researchers calculated annual birth prevalence rates and used regression analyses to evaluate changes over time and possible influences such as maternal age, total live births, and survey coverage. The annual prevalence of CL/P ranged from 0.11% to 0.21%, with an average of 0.14%. CL ± P ranged from 0.06% to 0.16% (mean 0.11%), while CPO remained lower and more stable, ranging from 0.02% to 0.04% (mean 0.03%). CL ± P gradually increased until 2013 but declined from 2014 onward. In contrast, CPO showed no clear long‐term change. Statistical comparisons revealed that the average prevalence of CL ± P was significantly lower during 2014–2023 than during 1983–2013, whereas no significant difference was found for CPO. Multiple regression analyses indicated that the decline in CL ± P after 2014 remained significant even after adjusting for maternal age and survey coverage. The observed decline in CL ± P birth prevalence may be associated with changes in the prenatal diagnostic environment; however, the present data cannot establish a causal relationship, and survey coverage may also have influenced the observed trend.