Impact of induced abortions and statistical definitions on perinatal mortality figures.

Two problems originating from the advanced use of medical technology in screening for malformations and in the care of preterm and low birthweight infants are presented: the impact of the increasing number of induced medical abortions and the differences in statistical definitions on perinatal mortality (PNM) figures. Data on 186,562 births registered in the Finnish Medical Birth Registry between 1987 and 1989 were studied, and 65,554 medical abortions (of which 1647 were performed after the sixteenth week of gestation) registered in the Abortion Registry between 1985 and 1990. A 115% increase in abortions for medical reasons in the period 1985-1990 was found. It was estimated that the trend accounted for up to one-third of the decline in PNM rate during that time. The perinatal mortality rate was strongly influenced by very small infants. The application of the Finnish version of the International Classification of Diseases, Ninth Revision (ICD-9) (including all livebirths and using both birthweight of 500 g and gestational age of 22 weeks as the criteria) resulted in PNM rates which were about 5% higher than according to ICD-9. We suggest that the impact of medical abortions on perinatal statistics has reduced the value of the perinatal mortality rate as an indicator of the standard of care.