Changes in the birth prevalence of orofacial clefts in Japan: Has the birth prevalence of orofacial clefts been affected by improved accuracy of prenatal diagnosis?

We have been conducting a survey on the birth prevalence of orofacial clefts, including cleft lip with or without cleft palate and cleft palate, in the Tokai area in central Japan every year for 37 years. Along with the yearly trends in the birth prevalence of orofacial clefts in that area for the past 37 years, we discuss whether the artificial abortion rate of fetuses with orofacial clefts has increased through the improved performance of ultrasonic imaging equipment. We also compare the yearly trends in the birth prevalence of congenital anomalies, including orofacial clefts, in Japan with those in other countries or areas where artificial abortion due to birth defects is legally permitted, and discuss the impact of improved accuracy of ultrasound imaging on the rate of artificial termination of pregnancy. The fact that the birth prevalence of orofacial clefts has basically remained unchanged for more than 30 years, even with recent more detailed prenatal diagnosis based on the improvement of ultrasonic diagnostic equipment, has allowed us tentatively to conclude that prenatal diagnosis is not currently threatening the right to life of the fetuses with orofacial clefts.