Temporal trends in perinatal mortality and cerebral palsy: A regional population-based study in southern Japan

The prevalence of cerebral palsy (CP) has not decreased in developed countries over the past 30 years. We examined gestational age-specific trends in the prevalence of CP.

This unselected, population-based study was conducted in Miyazaki prefecture, Japan (10,000 deliveries annually), where 102,999 deliveries were registered between 2001 and 2010. Of these, 312 were stillbirths (⩾22 weeks of gestation), 126 were neonatal deaths (<28 days of birth), and 214 infants were determined to be at risk of CP at peer-review conferences. Survival and neurological damage were compared for two 5-year periods, 2001-2005 and 2006-2010, and infants were classified according to gestational ages.

Stillbirths and neonatal deaths decreased significantly during both periods. Likewise, the number of registered high-risk cases of CP decreased by 30.2%, from 126 to 88 cases. After excluding congenital anomalies, the corrected CP prevalence was 1.5 per 1000 (78/51,889) and 1.3 per 1000 (67/51,110), for the two periods, which was not a significant difference. The number of extremely preterm infants (22-25 weeks) did not change over the 10-year period, whereas that of moderately preterm infants (26-36 weeks) increased, and that of term infants significantly decreased (p<0.01). In term infants, asphyxia decreased from 18 to 7 cases (p<0.05).

Perinatal deaths and CP decreased in prevalence during both 5-year periods, and the CP prevalence was 2.1 per 1000 births. Furthermore, fewer term infants were at high risk for CP mainly because of the reduced prevalence of asphyxia.