Good news for mothers-to-be: a new study found that using some antibiotics during the early phase of pregnancy will not cause birth defects.

The safety of antibiotic use during pregnancy has been a long point for debate. Several drugs have been labeled as dangerous for the fetus, though some can be considered safe to use during earlier stages of its development.

Researchers analyzed data from the Quebec Pregnancy Cohort, a study based on Canadian women and their babies. The data included information on the women's lifestyle and socioeconomic risk factors, pregnancy history and usage of medication and natural products.

The data collected allowed the researchers to discover connections between birth defects and the use of the antibiotics penicillin, erythromycin, azithromycin and clarithromycin during pregnancy.

Study author Dr. Anick Bérard of the University of Montreal explained that these antibiotics are the kinds of macrolides, which are some of the most commonly used drugs to treat infections, even during pregnancy.

But whether it is the infections or use of these macrolides that put women and their unborn child at risk for congenital birth defects and other unwanted pregnancy outcomes, something researchers hope to clarify in their study.

"We therefore aimed to estimate the risk of major congenital malformations after [fetal] exposure to the two most commonly used macrolides, and failed to find any," Bérard said.

The team compared the number of pregnancy defects in mothers who have taken penicillin and macrolide during pregnancy, amounting to more than 135,000 pregnancies. Among these pregnancies, more than 1 percent used macrolides during the first trimester of their pregnancy, while more than 9 percent of the pregnancies had newborns with major congenital defect.

"After statistical analysis, we found no meaningful association between the groups (women whose newborns had birth defects and those who took antibiotics during pregnancy) during their pregnancies, compared to penicillin use," said Bérard.

Researchers were also quick to note that the study is still unable to clarify what exactly causes the defects, as the antibiotics are also associated with causing these birth defects the same way the infections they typically target.

The team in conclusion, indicated a call for further research to confirm their findings and to test the safety of other less frequently used antibiotics, especially during pregnancy.

The findings of the study are published in the journal Pharmacoepidemiology and Drug Safety.