During pregnancy, using the anti-nausea drug Zofran may double your risk of having a baby with a “hole in the heart” like atrial septal defect or ventricular septal defect, according to two recent studies.
Studies Link Zofran and “Hole in the Heart” Defect Risk
The use of Zofran in the first trimester of pregnancy was linked to a doubled risk of “hole in the heart” defects and a 62% increased risk of heart defects overall, according to a study published by the medical journal Reproductive Toxicology in December 2014.
The conclusions of the study were based on data from 1,349 infants who were exposed to Zofran in the womb between 1998 and 2012.
According to the researchers:
“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 Finds 2X Risk of Heart Defects from Zofran
In 2013, the New England Journal of Medicine published a study that did not find any increased risk of birth defects associated with Zofran. However, half of the women took Zofran after the first trimester when their baby was no longer at risk of major birth defects.
Later that year, Dr. Jon T. Andersen published a follow-up study focusing only on data from first-trimester use of Zofran, and with more pregnancies (900,000) over more years (1997-2010). He concluded that Zofran doubled the risk of heart defects and increased the risk of birth defects by 30% overall.
What Are “Hole in the Heart” Defects?
In the first few weeks of fetal development, the heart separates into four chambers — two upper chambers (“atria”) and two lower chambers (“ventricles”). The left and right sides are separated by a wall called a septum. When there is a hole in this wall, the following “hole in the heart” defects occur:
- 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
The severity of the heart defect depends on the size of the hole. Small defects (under 5-mm in diameter) might never cause symptoms or need treatment, while large defects (over 8-mm) often cause severe complications immediately after birth.
Babies with a “hole in the heart” may suffer from low oxygen levels in their bloodstream, which can cause weakness, poor feeding, and failure to thrive.
The defect often forces more blood into the lungs, causing pulmonary hypertension. High blood pressure damages delicate blood vessels in the lungs, permanently damaging tissue.
The condition also forces the heart to work harder than normal, which causes it to enlarge and lose flexibility. Left untreated, this can lead to heart failure and death.