Meconium aspiration in the midtrimester fetus: an autopsy study

We studied the incidence, severity, and significance of intrauterine meconium aspiration (IUMA) in the midtrimester fetus. Lung sections from 219 midtrimester fetuses were examined for meconium, identified by finding meconium corpuscles. There were 21 cases (9.6%) with IUMA. Gestational age ranged from 13 to 23 weeks (mean 18.7 weeks); 11 were female, and 10 were male. Eighteen were spontaneous abortions, 11 of which were macerated, and 1 of these was associated with an intrauterine contraceptive device. There were 3 terminations of pregnancy, 2 for fetal abnormality and 1 for severe preeclampsia. One fetus was conceived by in vitro fertilization. Fifteen cases (71.4%) showed slight IUMA, 5 cases (23.8%) showed moderate IUMA, and in 1 case (4.8%) IUMA was massive. The incidence of IUMA in an autopsy series of midtrimester fetuses was 9.6%. The amount of aspirated meconium was usually small and possibly physiologic. When IUMA was moderate or massive, it was associated with severe abnormality of the umbilical cord or placenta, particularly subchorionic hematoma.