Sir.—With regard to the statement by Novack et al1 that they are unaware of any study in developed countries on the effects of perinatal factors on the time of umbilical cord separation, we wish to point out that we have already published such a study.2
Our study was carried out on a group of 911 infants born in the Netherlands. The perinatal factors we studied included the sex of the infant, its gestational age and birth weight, and the method of delivery, whether by cesarean section, vaginal delivery with the aid of forceps or ventouse, or unassisted vaginal delivery. We also studied the effects of the presence or absence of septicemia or other infections necessitating treatment with antibiotics and the presence or absence of jaundice in the newborn that required treatment with phototherapy. The effects of other various medical neonatal problems that necessitated admission to the Special