Purpose

This is called "Aim 1" of the investigators' NIH grant. Ondansetron (Zofran) is a safe and effective drug used in pregnant women to prevent nausea but the investigators do not know what effect pregnancy may have on the metabolism of Zofran in pregnant women or their babies. Therefore the investigators will enroll approximately 40 pregnant women and their babies and draw blood samples from the mother, the baby and the cord, to determine how much Zofran is in each sample of blood (called the pharmacokinetics or PK of Zofran). The pregnant women will receive Zofran, as a standard-of-care drug, for their scheduled Cesarean Section. The investigators will also enroll about 20 non-pregnant women undergoing surgery who will receive Zofran as standard-of-care during surgery. In both the pregnant & the non-pregnant women, the investigators will draw blood samples at the same time points based on number of minutes from the time the Zofran is given. The blood data (PK of Zofran) will help the investigators move into Aim 2 of the study, which will be done in pregnant, narcotic-addicted mothers and their babies who are born addicted to narcotics. Aim 2 will be listed separately as it will be an interventional study.