In more than 20 years on the market, the antibiotic Zithromax has found broad application as a treatment for many different types of bacterial infections.

However, medical science has only recently started to study the effects of antibiotics on developing fetuses, leaving open the possibility of a link between Zithromax and congenital birth defects.

What Is Zithromax?

Zithromax, also known by its generic name azithromycin, has been around since first getting FDA approval in 1991. Zithromax has been particularly popular because it can sometimes be taken in much shorter courses than other antibiotics. For that purpose, it is also sold as a single dose course called Zmax and a three-to-five day supply called a Z-Pak.

Despite Zithromax’s popularity, it comes with a risk of some potentially serious side effects. Instances of heart side effects and liver disease have been reported. And a recent investigation into antibiotic birth defects revealed a more significant link than previously realized.

Birth Defect Study

In 2009, a study by the Centers for Disease Control revealed an unexpectedly frequent occurrence of birth defects in conjunction with some of the most common antibiotic medications used to treat urinary tract infections. The study was published in the Archives of Pediatric and Adolescent Medicine in November 2009.

Researchers reviewed the records of more than 13,000 mothers who gave birth to children with one of 30 major birth defects. For comparison, they also reviewed records from almost 5,000 mothers in the same geographical regions who gave birth to healthy babies.

Women who reported having taken antibiotics anywhere from one month before their pregnancy to the end of their first trimester were considered exposed to antibiotics.

Researchers found that many different types of antibiotic birth defects were associated with two types of drugs in particular: Sulfa drugs and nitrofurantoins.

Women whose children had been born with ancephaly – a fatal underdevelopment of the brain and skull – were three times as likely to have taken a sulfa drug during pregnancy.

Other defects associated with sulfa drugs included aortic coarctation, hypoplastic left heart syndrome, choanal atresia (a block in the nasal passage), diaphragmatic hernia (an opening in the diaphragm that causes difficulty breathing), and underdeveloped or missing limbs.

Nitrofurantoins were associated with cases of certain eye defects and heart defects. Mothers who gave birth to children with cleft lip and cleft palate were twice as likely to have taken nitrofurantoins during pregnancy.

While the study did not find a causal connection between antibiotics and birth defects, the researchers noted that the correlation between the two was strong enough to warrant further investigation.

This study was significant for being the first large-scale look at the effects of antibiotics on pregnancy. Many of the drugs tracked have been prescribed for years without their effects on pregnancy ever being cataloged.

Researchers noted that information on the effects of many drugs on developing fetuses is lacking, due in part to ethical considerations that restrict clinical studies on pregnant women.

Even though it did not cover Zithromax, the study revealed the need for further analysis of the risks of antibiotic birth defects. It is possible that women who give birth to children with birth defects after taking Zithromax during pregnancy may have grounds for a Zithromax lawsuit.