THURSDAY, March 22 (HealthDay News) -- Pregnant women taking the antidepressants known as selective serotonin reuptake inhibitors (SSRIs) face a slightly increased risk of developing dangerously high blood pressure, Canadian researchers report.

This condition, known as preeclampsia, can harm both mothers and their unborn infants, the researchers noted. However, this association may not be cause-and-effect, so women should not just stop taking these medications but should consult with their doctor if they are concerned, they stressed. Two of the most commonly prescribed SSRIs are Paxil (paroxetine) and Prozac (fluoxetine).

"We know that antidepressants should be used during pregnancy, but they should be used with caution," said lead researcher Anick Berard, director of the research unit of medications and pregnancy at CHU Ste-Justine's Research Center and a professor with the Faculty of Pharmacy at the University of Montreal.

The association between SSRIs and hypertension is a new finding, she added.

The report was published in the March 22 issue of the British Journal of Clinical Pharmacology.

For the study, Berard and her colleague, Mary De Vera, collected data on women in the Quebec Pregnancy Registry. They looked at more than 1,200 women who had high blood pressure during pregnancy that did or did not result in preeclampsia and who had no history of high blood pressure before pregnancy, and compared them with more than 12,000 healthy women.

They found women taking SSRIs had a 60 percent higher risk of developing high blood pressure. In absolute terms, the risk went up from 2 percent to 3.2 percent.

It appears that all SSRIs are not equal when it comes to risk, however. For instance, for women taking Paxil the risk was increased 81 percent, or to 3.6 percent in absolute terms.

"It's a big relative increase, but if you look at absolute risk it is 1 percent," Berard said.

These findings are important because SSRIs are the most common drugs used to treat depression, and of the estimated 20 percent of women who suffer from depression during pregnancy, between 4 percent and 14 percent take antidepressants, the researchers said.

Commenting on the study, Dr. Gene Burkett, a professor of obstetrics and gynecology at the University of Miami Miller School of Medicine, said that "this study has severe limitations. There are a lot of factors in preeclampsia they do not account for, so they don't show a cause-and-effect relationship."

However, pregnant women should be concerned about SSRIs for a lot of other reasons, he said. The medications have been linked to lower birth weights, he noted.

"Every physician has to measure the risk of taking an SSRI vs. the risk of not taking it in patients who really need it," Burkett said.

"If the patient is really in need of it, then you have to give it to them, because the consequences, especially after delivery, of those patients who are depressed can be anything up to suicide or killing their infant; these are the extremes," he said.

"We do see cases of women whose depression gets worse after delivery and wind up killing their babies," he said. "Those patients benefit from SSRIs, and the benefits may be greater than the risks of not taking them."

However, many women with mild depression may be able to cope without SSRIs, Burkett said. "But if you do take a woman off an SSRI during pregnancy, they need to be followed closely," he noted.

"In some cases you cannot take women off SSRIs; in other cases you can; you have to evaluate each woman individually," Burkett said.

Research published earlier this month also found risks associated with SSRI use during pregnancy. Dutch doctors reported that the medications were associated with delayed head growth of the fetus.

"Fetal body growth is a marker of fetal health, and fetal head growth is a marker for brain development," said lead researcher Hanan El Marroun, a postdoctorate fellow in the department of child and adolescent psychiatry at Sophia Children's Hospital and Erasmus Medical Center in Rotterdam. "We found prenatal exposure to SSRIs was associated with decreased growth of the head, but not decreased growth of the body."

More information

For more information on pregnancy and depression, visit the American Pregnancy Association.