Two studies have found that the anti-vomiting drug Zofran doubles the risk of having a baby with a heart defect, including “hole in the heart” defects like atrial septal defect and ventricular septal defect.
Study Finds Zofran Doubles Risk of “Hole in the Heart” Defects
In December 2014, the journal Reproductive Toxicology published a study linking the use of Zofran with a 62% increased risk of heart defects overall, including a doubled increased risk of “hole in the heart” defects, such as atrial septal defect and ventricular septal defect.
Conclusions were based on data from Sweden, including 1,349 infants born of women who took Zofran in early pregnancy between 1998 and 2012.
The researchers warned:
“If an association between the use of ondansetron and an increased risk for cardiovascular defects is true, the strongly increasing off label use of the drug at nausea and vomiting in early pregnancy must be regarded as unsuitable and should be avoided.”
Another Study Links Zofran and Heart Defects
In 2013, a study published in the New England Journal of Medicine found no evidence linking Zofran and birth defects. However, the average gestational age of exposure was 10 weeks, suggesting that half of the pregnant women used Zofran after the first trimester when their fetus was no longer at risk of most major birth defects.
Later that year, a follow-up study by Dr. Jon T. Andersen focused only on first-trimester use of Zofran. Dr. Andersen also looked at more pregnancies (900,000) over a longer period of time (1997-2010). He found that Zofran increased the risk of birth defects by 30%, mostly due to a doubled increased risk of heart defects.
Case Reports in Canada Link Zofran and “Hole in the Heart”
In June 2014, an investigation by the Toronto Star reported 20 cases of Canadian women who had a baby with a birth defect after using Zofran, including multiple reports of heart defects and one baby who had a “hole in the heart” (atrial septal defect).
Types of “Hole in the Heart” Defects
- Atrial Septal Defect: Hole between the two upper chambers of the heart (“atria”)
- Ventricular Septal Defect: Hole between the two lower chambers of the heart (“ventricles”)
What is the problem?
“Hole in the heart” birth defects occur during the first trimester. Normally, as a baby develops in the womb, a wall (“septum”) forms and divides the heart into four chambers. If the wall does not form properly, a hole remains after birth.
Small holes cause few problems and do not need treatment. However, large holes can result in low-oxygenated blood in the child’s body.
When blood flows between the upper or lower heart chambers, pressure builds up in the lungs (called “pulmonary hypertension”). Over time, delicate blood vessels in the lungs are permanently damaged due to high blood pressure.
The right side of the heart must work even harder to compensate, which can cause the muscle to enlarge, stiffen, and lose the flexibility it needs to pump efficiently. This can lead to heart failure and death.
Symptoms of a Hole in the Heart
- Heart murmur (abnormal sound a doctor hears using a stethoscope)
- Fast and hard breathing
- Shortness of breath with activity
- Failure to gain weight or thrive
- Sweating while feeding
- Frequent respiratory infections in children