Pregnancy has historically been described as a time of emotional well-being, providing “protection” against psychiatric disorder, but a new study says the hormonal changes which occur during pregnancy do not protect women from depression, and those taking antidepressants may need to continue despite concerns about fetal damage.

Depression is a highly prevalent illness in women and frequently has its onset during the childbearing years.

According to Dr. Lee Cohen, of Massachusetts General Hospital in Boston who led the research, patients who stopped their antidepressant during pregnancy were five times more likely to have a return of depressive symptoms than those patients who had decided to continue their medication during pregnancy.

The relapse rate was about the same as it would be for non-pregnant women who cut back or stopped using their antidepressants, the report said.

The study looked at a total of 201 pregnant women between March 1999 and April 2003 from 3 centers with specific expertise in the treatment of psychiatric illness during pregnancy.

The women who had suffered from severe depression before conception kept taking their medicine or tried to eliminate or reduce it out of fear it might hurt the fetus.

Of the 201 women in the sample, 86 experienced a relapse of major depression during pregnancy.

Among the 82 women who maintained their medication throughout their pregnancy, 21 relapsed compared with 44 of the 65 women who discontinued medication.

Women who discontinued medication relapsed significantly more frequently over the course of their pregnancy compared with women who maintained their medication.

Of the 201 women who were followed up across the study and who were eligible for analysis, 13 miscarried, 5 electively terminated their pregnancy, 12 were lost to follow-up prior to completion of pregnancy, and 8 chose to discontinue participation in the study.

Race was the only significant factor distinguishing those who were lost to follow up with nonwhites being more likely to be lost.

Cohen says it is clear that pregnancy does not protect women against depression during pregnancy through hormonal and other biological changes that occur.

The researchers also say they have not found that antidepressants lead to major birth defects but do admit that several recent reports have suggested a possible link between some drugs and a heart malformation, and distress among some newborns exposed in the womb.

Cohen says the findings have important clinical implications and suggest that pregnancy is not uniformly protective against major depression.

Women with histories of depression should be aware of the risk of depressive relapse during pregnancy if they discontinue their medication.

Such women says the study need to weigh up concerns about prenatal exposure to these medications against the risks of depressive relapse during pregnancy and the effects of untreated depression on fetal and maternal well-being.

The study is published in the Journal of the American Medical Association.