Joining a debate about the use of a class of antidepressants during pregnancy, Researchers from the Centers for Disease Control, confirmed birth defects and some drugs were linked.
Their analysis, published in the BMJ on Wednesday, involved 17,952 mothers of children born with birth defects. It also covered 9,857 mothers of children without birth defects born between 1997 and 2009 at 10 centres.
SSSRI's or selective serotonin reuptake inhibitors were taken by a total of 1,285 of the participants, during one month before conception through the first trimester of pregnancy - the period during which the fetus was believed to be most vulnerable.
Zoloft (sertraline) was the drug most commonly used by study participants with Prozac (fluoxetine) and Paxil (paroxetine), Celexa (citalopram), and Lexapro (escitalopram) following in the order of use.
Birth defects were alarmingly common, affecting one in every 33 babies born in the US, but scientists were still in the early stages of determining what caused most of them.
The Food and Drug Administration first issued an advisory warning of a potential association in December 2005 between paroxetine and heart defects in infants. Since then researchers had launched numerous studies to try to confirm the problem but had come to conflicting conclusions.
The study found that many popular antidepressants - Celexa, Lexapro or Zoloft - were not associated with birth defects and only two in the study, Prozac, sold generically as paroxetine, and Paxil, sold generically as fluoxetine, were implicated.
Also in women who took those two drugs in early pregnancy, birth defects occurred 2 to 3.5 more frequently as compared with women who did not take them.
The use of Prozac was associated with a birth defect in which a baby's skull was misshapen, while Paxil use was associated with a defect in which a baby's intestines protruded outside the body and with anencephaly, in which a baby was missing parts of the brain and skull, the study found.
The researchers found that Paxil and Prozac were linked to a heart defect.
However, the authors noted that the risks appeared to be small. For instance, in women who took paroxetine early in pregnancy, the risk for anencephaly increased from 2 cases per 10,000 to 7 per 10?000.