This document discusses a cohort study examining the risks of the drug ondansetron, which is used to treat nausea and vomiting during pregnancy. The study followed a large group of pregnant women exposed to ondansetron and compared outcomes like abortion, birth defects, preterm birth, and low birth weight to unexposed women. The study found no significant increase in these risks with exposure to ondansetron during pregnancy. While definitive conclusions cannot be made, the results provide reassurance about the safety of using this drug to treat nausea and vomiting during pregnancy.

1. Ondansetron in Pregnancy
Nausea and vomiting are common during pregnancy, affecting more than
half of all pregnant women.
Whereas these symptoms can be managed conservatively in most pregnant
women, 10 to 15% receive drug treatment..
Because nausea and vomiting manifest in early pregnancy, with onset
between 3 and 8 weeks of gestation and with peak symptoms in weeks 7 to 12
in most cases.
Drug treatment often coincides with the period during which the fetus is most
susceptible to teratogenic effects.

2. A cohort study or panel study is a form of longitudinal study (a type of
observational study) used in medicine, social science, actuarial science,
business analytics, and ecology. It is an analysis of risk factors and follows a
group of people who do not have the disease, and uses correlations to
determine the absolute risk of subject contraction. It is one type of clinical
study design and should be compared with a cross-sectional study. Cohort
studies are largely about the life histories of segments of populations, and
the individual people who constitute these segments.
METHODS Study
Cohort

3. Conclusion:
In this registry-based cohort study, we
found that exposure to ondansetron in pregnancy
was not associated with a significant increase in the
risk of spontaneous abortion, stillbirth, any major
birth defect, preterm delivery, or infants born with
low birth weight or born small for gestational age.
Although these results cannot definitively rule out
the possibility of adverse effects in association with
ondansetron, the results do provide reassurance
regarding the use of this agent for nausea and
vomiting in pregnancy.

4. Reference
Björn Pasternak, Henrik Svanström, and Anders Hviid,
N Engl J Med 2013; 368:814-823February 28, 2013