Why does meconium staining occur predominantly in infants older than 36 weeks of gestational age?

Question

Quizplus · Accepted Answer

Meconium passage into the amniotic fluid requires strong peristalsis and anal sphincter tone, which is not common in preterm infants. Meconium aspiration syndrome rarely occurs in infants born at less than 36 weeks of gestation. The longer a pregnancy is allowed to continue past 42 weeks, the greater the chances are of the passage of meconium.

Why Does Meconium Staining Occur Predominantly in Infants Older Than