What is the term for the first meconium stool passed by the newborn?

The term that denotes the first meconium stool passed by the newborn is meconium itself. Meconium is composed of various materials ingested by the fetus during its time in utero, including amniotic fluid, mucus, lanugo, and bile. This dark greenish-black, tar-like substance typically is passed within the first 24 to 48 hours following birth, though it can sometimes occur earlier.

The other terms are related to newborn characteristics or substances but do not refer specifically to the first stool. Colostrum is the early form of breast milk produced in the first few days post-delivery, rich in antibodies and nutrients. Lanugo refers to the fine, soft hair that covers a fetus and newborn and is often shed prior to birth or shortly thereafter. Vernix is a greasy, waxy substance found on the skin of newborns that serves to protect their delicate skin from the amniotic fluid. Each of these plays its own role in the newborn's health and development but does not specifically identify the first stool.