Relevance of the gestational age distribution of meconium passage in utero.

The incidence of meconium staining of the amniotic fluid among the admissions to a newborn special care unit was determined. Meconium staining of the amniotic fluid was present in 251 (7.5%) of 3,374 admissions. The majority of those with meconium staining (98.4%) was of 37 weeks gestation or greater and none was less than 34 weeks gestation. The possible relevance of this gestational age distribution is discussed.