Inclusion of early fetal deaths in a birth defects surveillance system.

This investigation evaluated the impact of collecting data on early fetal deaths (less than 20 weeks' gestation) on a birth defects surveillance system. Data were obtained from the Hawaii Birth Defects Program (HBDP), a statewide registry for Hawaii with active case ascertainment methodology. In 1986 through 1997, 257 early fetal deaths with birth defects were identified, representing 2.2% of the total birth defects cases. Two hundred sixteen (84.1%) of the early fetal deaths had chromosomal defects (mainly trisomies, polyploidies, and Turner syndrome) and 59 (23.0%) had structural defects. Most (65.4%) of the early fetal deaths with chromosomal defects occurred at 8-12 weeks' gestation, and 62.3% of the early fetal deaths with structural defects occurred at 16-19 weeks' gestation. For half of the 26 specific birth defects examined, early fetal deaths accounted for at least 4% of all cases. The proportion of total birth defects cases accounted for by early fetal deaths increased over the 12-year period of the study (p = 0.003). Most of this secular trend appeared to result from an increase over time in early fetal deaths where a birth defect was prenatally detected (p = 0.004). Although ascertainment of early fetal deaths is not believed to be complete, their inclusion in a birth defects registry may be beneficial because of confusion about the pregnancy outcome and/or gestational age reported in the medical record, their importance in cluster investigations, and their contribution to birth defects prevention strategies.