Anti-depressants were found to have some links with birth defects but not all, a research by the Centers for Disease Control reported.

The CDC looked into the use of a class of antidepressants called selective serotonin reuptake inhibitors (SSRI) during pregnancy to determine whether or not it significantly causes birth defects.

The results of the findings, published in the BMJ on Wednesday, was participated by 17,952 mothers whose children were born with defects and another 9,857 mothers of children without birth defects born from 1997 until 2009 in 10 centers.

Around 1,285 mothers reported taking SSRIs a month before they conceived until the end of their first trimester of pregnancy, which is considered to be the period where the baby is most susceptible to chances of birth defects.

The most common SSRIs reportedly taken by the participating mothers included Zoloft (sertraline), followed by Prozac (fluoxetine) and Paxil (paroxetine), Celexa (citalopram) and Lexapro (escitalopram).

About one in 33 babies born in the U.S. were affected by birth defects. Scientists have not yet found the many culprit of birth defect. The Food and Drug Administration (FDA) already warned about the use of paroxetine and the possibilities of heart defects for infants.

The trials, however, could not point out if SSRIs actually cause birth defects.

Dr Jan Friedman, a professor of medical genetics at the University of British Columbia, maintained that the results of the study should be taken into context.

"We talk a lot about the fact that there are all these studies and they don't agree. The fact is they do agree, in the big picture," Friedman said.

Friedman explained that SSRIs are not "really dangerous drugs"  but his team assessed if the increased rates of 14 different birth defects among the off springs of mothers were directed in the use of SSRIs.

Likewise, the study did not find any connection between birth defect and the use of drug sertraline (sold as Zoloft), although earlier studies did.  Mothers who used Paroxetine (Paxil) and fluoxetine (Prozac), meanwhile, were found to bear off springs with birth defects on the child's heart or stomach. Paroxetine was also linked to increased chances of anencephaly, a condition wherein the fetus's brain failed to completely develop. In general, birth defects were rarely recorded, like  to 7 per 10,000 for the chances of anencephaly10 to 24 per 10,000 for cases of cardiac defects for those who took paroxetine.