International Board of Certified Lactation Consultant (IBCLC) Practice Exam

What substance causes the dark color of meconium?

1. Bile/bilirubin

2. Amniotic fluid

3. Colostrum

4. Meconium itself

The correct answer is: Bile/bilirubin

The dark color of meconium is primarily caused by bile and bilirubin. Meconium, which is the first stool passed by a newborn, contains a mixture of materials the fetus ingests while in utero, including bile and cells from the intestinal lining. Bilirubin, a breakdown product of hemoglobin from red blood cells, imparts a dark green or blackish hue to the meconium. The presence of bile not only contributes to the color but also indicates fetal liver function. Meconium itself, while responsible for the substance's composition, does not define its color; rather, it is the bilirubin and bile that provide the characteristic dark coloration. Amniotic fluid and colostrum do not contribute to the coloration of meconium, as they have different compositions and functions in pregnancy and lactation. The dark color can vary, but the key factor in its appearance is the presence of these substances related to the newborn's physiological processes.