Zofran Atrial Septal Defect

When pregnant women use Zofran to control morning sickness, studies have found evidence that they may be more likely to have a baby with a heart defect, including atrial septal defect.

Zofran and Atrial Septal Defect

Zofran (ondansetron) is an anti-nausea drug made by GlaxoSmithKline (GSK). Although it is only FDA-approved for chemotherapy patients, it is commonly used “off-label” by pregnant women suffering from morning sickness.

The problem is that no one knows if Zofran is safe during pregnancy. A report published by the Toronto Star in June 2014 highlighted nearly two dozen cases of women who used Zofran and had a baby with a birth defect.

According to one case:

“A doctor reported that [Zofran] was the suspected cause of a baby’s mouth deformity, jaundice, heart murmur and two heart defects, including “atrial septal defect,” otherwise known as a hole in the heart.”

This is not the first time Zofran has been linked to birth defects. Zofran was linked to a 30% overall increased risk of birth defects, mostly due to an excessive number of heart defects, in a study published in August 2014. Conclusions of the study, titled “Ondansetron use in early pregnancy and the risk of congenital malformations,” were based on nearly 900,000 pregnancies in Denmark.

Swedish Researchers Find Zofran Doubles Risk of Septal Heart Defects

Swedish researchers have published a study finding that Zofran doubled the risk of “hole in the heart” defects. Conclusions were published in December 2014, published in Reproductive Toxicology, based on data from 1998-2012, and included nearly 1,400 babies who were exposed to Zofran during the first trimester.

Atrial Septal Defect – “Hole in the Heart”

Atrial Septal Defect (ASD) is one of the most common heart defects. Normally, the heart is separated into four chambers — two on the left and two on the right. The upper chambers (“atria”) are separated by a wall (“septum”).

All babies develop with a hole in the heart, but it does not cause problems because the fetus receives oxygen from its mother. The holes normally close just before birth. If they do not, the baby is born with a heart defect.

What is the problem?

The severity of the condition depends on the size of the hole. Small ASDs (under 5mm) often close on their own, cause no symptoms, and never need treatment.

Large ASDs (over 8mm) can cause oxygen-poor blood to mix with oxygen-rich blood. This “mixed” blood does not have enough oxygen, and the baby may appear blue, lethargic, weak, or fail to thrive and grow normally.

Complications

Over time, delicate tissues in the lungs may be severely damaged by abnormally high blood pressure (pulmonary hypertension). ASD also causes the right side of the heart to work harder than normal. Eventually, the heart muscle will thicken, lose flexibility, weaken, and fail.