Whose Blood Is It, Anyway?; April 2001; Scientific American Magazine; by Ronald M. Kline, sidebar by Carol Ezzell; 8 Page(s)

Wrinkly-faced, slippery and squalling, the newborn makes her debut into the world. As the parents share their joy and begin to count 10 perfect little fingers and 10 adorable tiny toes, they scarcely pay attention to birth's Act Two: the delivery of the placenta, or afterbirth.

After the ordeal of labor, most new mothers are happy they need to push only once more for their physician to scoop up the roughly one-pound, pancakelike organ that nourished their baby through the umbilical cord for nine months. After cutting the cord and checking the afterbirth for gaps and tears that might indicate that a piece still remains inside the mother's uterus-where it could cause a potentially fatal infection-the doctor usually tosses it into a stainless-steel bucket with the rest of the medical waste bound for incineration.