Negative effect of a short interpregnancy interval on birth weight following loss of an infant to sudden infant death syndrome.

It was hypothesized that a short interpregnancy interval immediately following the birth of an infant that had succumbed to sudden infant death syndrome (SIDS) (and no other cause of death) would be associated with a reduced mean birth weight in the next infant. Mothers who had given birth to two children in the state of Oregon between 1975 and 1984 and whose first child had died in infancy from either SIDS (n = 84) or some other cause (n = 305) were identified from vital records. A multiple regression analysis in which adjustment was made for possible confounding variables (including the birth weight of the deceased child) was conducted. When the firstborn child had succumbed to SIDS, the mean birth weight of the next baby was 314 g (2,978 g vs. 3,292 g, p = 0.04) lower when the interpregnancy interval was less than 6 months versus greater than 6 months. In contrast, a less-than-6-month interval had a slightly positive effect (60 g) on the mean birth weight of the next baby when the firstborn child had died due to a cause other than SIDS. These results suggest that parents who have lost a child to SIDS may wish to delay a new pregnancy for at least 6 months.