The use of Zofran in the first few months of pregnancy may double the risk of having a baby with a heart defect, such as ventricular septal defect, according to several recent studies.
Zofran and Ventricular Septal Defect
Most major heart defects occur very early in pregnancy, usually before the 8th week. During this time, the mother’s body is undergoing major hormonal changes. Over 75% of pregnant women have morning sickness (nausea and vomiting) during the first trimester, and many of them use Zofran.
The problem is that a number of recent studies have found higher rates of heart defects in babies who were exposed to Zofran in the womb.
One recent study, published in December 2014 by Reproductive Toxicology, found a 62% increased risk of heart defects, including a doubled risk of cardiac septal defects, associated with first-trimester use of Zofran. These defects include ventricular septal defect and atrial septal defect.
About a year before that study was published, another study linked Zofran with a 30% increased risk of birth defects, mostly due to a doubled risk of heart defects. Conclusions were published by Dr. Jon T. Andersen and based on data from nearly 900,000 pregnancies in Denmark from 1997-2010.
Ventricular Septal Defects (VSD)
Normally, the heart divides into four chambers during the first few weeks of pregnancy. A wall called a “septum” separates the lower chambers (ventricles). If it does not form completely, a hole remains and the baby is born with a “hole in the heart.”
What is the problem?
Babies with a ventricular septal defect are at risk of many complications. One major problem is “shunting” of blood through the hole, which results in oxygen-rich blood mixing with oxygen-poor blood. This mixed blood is pumped into the child’s body, but it does not contain enough oxygen.
Symptoms of a ventricular septal defect may include:
- Heart murmur (abnormal sound heard with a stethoscope)
- Rapid and heavy breathing
- Poor feeding or tiring easily while feeding
- Failure to gain weight or thrive
- Pulmonary hypertension: or high blood pressure in the lungs. It occurs when blood leaks through the hole and heart forces too much blood into the lungs, causing severe damage to delicate blood vessels in the lungs.
- Heart Failure: Over time, the right side of the heart must work harder. If the defect is not repaired, the muscle will thicken and lose the flexibility it needs to pump effectively. This can lead to heart failure and death.
- Growth Failure: The risk is especially high in infants, who may lose weight or fail to grow and develop normally.
- Arrhythmias: Heart rhythm problems can occur due to extra blood flowing through the heart, which causes it to stretch and enlarge. Ventricular septal defects can also disrupt the heart’s normal electrical activity, leading to irregular heartbeats.