Meconium is a collection of secretions and desquamated cells from the digestive tract, and waste products from ingested amniotic fluid. It begins to appear towards the beginning of the second trimester and accumulates in the colon until birth.

When is meconium formed?

Meconium is formed by the fetus as early as the 12th week of gestation, accumulates throughout pregnancy, and is normally excreted after birth by the infant.

What is meconium made of?

The first bowel movement a baby has is called meconium. Meconium is composed of amniotic fluid, mucus, lanugo (the fine hair that covers the baby's body), bile, and cells that have been shed from the skin and the intestinal tract. Meconium is thick, greenish black, and sticky.