Prevalence of neural tube defect in southern Thailand: a population-based survey during 2009-2012

Neural tube defects (NTDs) are a group of congenital malformation of the central nervous system that leads to permanent physical disability and requires lifelong treatment. In Thailand, there have been three published articles on NTDs, all hospital-based studies, which found prevalence of NTDs of 4.8-6.7 per 10,000 live births.

It was our purpose with this study to determine the prevalence and type of NTDs in southern Thailand through a population-based survey.

Data were obtained through the population-based surveillance during 2009-2012 in three provinces (Songkhla, Phatthalung, Trang) in southern Thailand. Entries in the birth defects registry included all live births, all stillbirths after 24-week gestational age, and termination of pregnancy following the prenatal diagnosis at any gestational age of all congenital anomalies.

During 2009-2012, 148,759 births were registered in the three provinces. Twenty-eight NTD cases were identified, giving an average of 1.88 per 10,000 births (95 % CI 1.20-2.51): 12 cases with anencephaly (42.8 %), 5 with occipital encephalocele (17.9 %), and 11 with myelomeningocele (39.3 %). The birth prevalence per 10,000 births of anencephaly, encephalocele, and myelomeningocele were 0.81, 0.33, and 0.74, respectively. Sixteen (57 %) were detected in live births, and 12 (43 %) were detected by prenatal diagnosis which later resulted in termination of pregnancy.

The prevalence of NTDs based on the population-based study in southern Thailand was low. About 40 % of NTD cases were detected prenatally and later terminated. Hence, examining only registry live births will result in an inaccurately low NTD prevalence rate.