Birth Defect Risk Linked To Zithromax, Similar Antibiotics Use During Pregnancy: Study

Side effects of antibiotics like Zithromax, Zpack, Biaxin and other widely used drugs may increase their risk of birth defects when used by pregnant women, according to the findings of a new study.

In a study published this week in the medical journal The BMJ, researchers from the U.K. warn that use of a class of antibiotics known as macrolides during pregnancy may disrupt the development of the fetus, resulting in major malformations in general, and particularly an increased risk of cardiovascular and genital malformations.

Macrolides are a popular class of antibiotics frequently prescribed to treat common bacterial infections like respiratory infections, skin and soft tissue infections and sexually transmitted diseases. They include Zithromax, also known as Zpack or Zmax, as well as Biaxin, Dificid and Erythromycin.

In this latest study, researchers looked at data from nearly 105,000 children born between 1990 to 2016, whose mothers were prescribed either a macrolide antibiotic or penicillin. The three macrolides specifically tested in the study were Zithromax, Biaxin and erythromycin.

For every 1,000 mothers given macrolides during pregnancy, 21.55 were born with major malformations, according to the findings. That compares to only 17.36 per 1,000 among mothers given penicillin.

The researchers determined that giving macrolides during the first trimester of pregnancy increased the risk of major malformations by 55%, while specifically increasing the risk of cardiovascular malformations by 62%. Giving macrolides to a pregnant woman at any time during pregnancy resulted in a 58% increased risk of genital malformations, particularly hypospadias; where the urethra opening is on the underside of the penis instead of at the tip.

The study also found that erythromycin appeared to have the strongest link to such malformations compared to other macrolides tested.

“Prescribing macrolide antibiotics during the first trimester of pregnancy was associated with an increased risk of any major malformation and specifically cardiovascular malformations compared with penicillin antibiotics. Macrolide prescribing in any trimester was associated with an increased risk of genital malformations,” the researchers concluded. “These findings show that macrolides should be used with caution during pregnancy and if feasible alternative antibiotics should be prescribed until further research is available.”

Currently, macrolide warning labels generally carry no pregnancy risk warnings. However, Canadian researchers raised warnings as early as July 2017 about the potential risk of birth defects associated with this class of antibiotics.

In a study published in the British Journal of Clinical Pharmacology, they found an increased risk of malformations linked to various types of macrolides; each of which was associated with a different type of malformation.

Zithromax and Macrolide Heart Concerns

Previous research has shown Zithromax and other macrolide antibiotics may increase the risk of serious and potentially life-threatening heart problems.

In a 2015 study published by the Journal of the American College of Cardiology, Chinese researchers warn that the use of Zithromax or Zmax more than doubles the risks of sudden cardiac death or heart rhythm problems.

That study found the rates of sudden cardiac death and ventricular tachyarrhythmia’s (VTA) was about 2.5 times higher for those taking Zithromax and similar antibiotics, such as Biaxin, quinolone, and erythromycin, than those taking no antibiotics at all.

The FDA has previously issued Zithromax drug safety communications, warning that the antibiotic can cause serious and potentially fatal abnormal heart activity. The FDA indicated that Zithromax can disrupt the electrical activity of the heart. The agency’s conclusions came after an investigation into the risk of Zithromax heart issues that was started in May 2012, examining data from a number of studies.