To determine whether placental abnormality (placental abruption or placental previa) during pregnancy
predisposes an infant to a high risk of sudden infant death syndrome (SIDS), the authors conducted a
population-based case-control study using 1989-1991 California linked birth and death certificate data. They
identified 2,107 SIDS cases, 96% of whom were diagnosed through autopsy. Ten controls were randomly
selected for each case from the same linked birth-death certificate data, matched to the case on year of birth.
About 1.4% of mothers of cases and 0.7% of mothers of controls had either placental abruption or placenta
previa during the index pregnancy. After adjustment for potential confounders, placental abnormality during
pregnancy was associated with a twofold increase in the risk of SIDS in offspring (odds ratio = 2.1, 95%
confidence interval 1.3-3.1). The individual effects of placental abruption and placenta previa on the risk of SIDS
did not differ significantly. An impaired fetal development due to placental abnormality may predispose an infantto a high risk of SIDS.
<http://aje.oxfordjournals.org/content/149/7/608.full.pdf>Am J Epidemiol 1999; 149:608-11.