Evaluating the risks of cesarean section: low Apgar score in repeat C-section and vaginal deliveries.

Data from Washington State birth certificates from 1980-83 were used to estimate excess risk to the infant delivered via repeat cesarean section independently of any risk associated with the indication for the procedure. Using a case-control design, we compared the method of delivery of all infants with low (0-6) five-minute Apgar scores born to multiparous mothers after uncomplicated pregnancies and births to that of similar infants with a high score (7-10), frequency matched by birthweight. Of the 1,030 infants with low Apgar score, 127 (12.3 per cent) were delivered via repeat cesarean section, in contrast to 98 (9.8 per cent) of 998 controls with high Apgar score. In a regression model controlling for birthweight, gestational length, maternal age, and income the relative risk was 1.29 (95% confidence interval 0.97, 1.72). Excess risk was highest among babies of normal (2500-4000 grams) birthweight. While a number of limitations inherent in the source of data require cautious interpretation of these results, we conclude that some excess risk of low Apgar score may be associated with repeat cesarean section procedures.