"A recently published case-control study has shown that infants born to mothers who took selective serotonin reuptake inhibitors (SSRIs) after the 20th week of pregnancy were 6 times more likely to have persistent pulmonary hypertension (PPHN) than infants born to mothers who did not take antidepressants during pregnancy."
PPHN infants have difficulty making the transition from breathing inside the womb to normal breathing after delivery, often leading to respiratory failure that requires mechanical ventilation. Even when treated, between 10% to 20% of babies born with PPHN do not survive.
Between 1998 and 2003, the research team interviewed 377 women who had recently given birth to a baby with PPHN, with questions about medical history and the drugs taken during pregnancy and found that 3.7% of the infants had been exposed SSRIs after the 20th week of pregnancy, or about 6 times the rate among healthy infants in a comparison group born at the same time.
Infants with PPHN typically show abnormal muscle cell growth in their respiratory system. Previous investigations have found that SSRIs tend to accumulate in adult users' lungs and serotonin can promote the proliferation of certain muscle cells. This may explain how the drugs could have an effect on the developing fetus, according to the study authors in the NEJM.
This birth defect is also not as rare as once thought. After the results of the PPHN study were released in February 2006, the lead author and researcher, Dr Christina Chambers, told the Wall Street Journal that women contacted her from all over the US who had given birth to babies with PPHN after using SSRIs during pregnancy.
Medical experts say its important to recognize that Pfizer promotes Zoloft for many disorders besides depression, meaning women may be taking the drug even though they have never been diagnosed with depression. According to the FDA, in addition to depression, Zoloft is approved to treat obsessive-compulsive disorder, panic disorder, social anxiety disorder, post-traumatic stress disorder, and premenstrual dysphoric disorder.
In March 2006, Health Canada issued its own warning, "advising women who are taking antidepressants known as selective serotonin reuptake inhibitors and who are pregnant or intend to become pregnant to discuss the situation with their doctor, due to potential risks to the baby."
On April 7, 2006, the BBC reported that a Canadian study from the University of Ottawa of almost 5,000 mothers found that SSRI use during pregnancy doubled the risk of delivering a stillborn baby and that women who took the drugs were also more likely to have a premature or low-birth-weight baby.
The study found almost 20% of women who used SSRIs gave birth prematurely, compared to 12% of those who did not use the drugs and that babies born to women using SSRIs were also more likely to have seizures.
On August 25, 2006, Reuters Health reported another Canadian study that found that babies born to women who took SSRIs during pregnancy appear to be at increased risk of having a low birth weight and to develop respiratory distress.
Lead investigator Dr Tim Oberlander told Reuters that "our study was undertaken to distinguish the effects of maternal mental illness -- pregnancy-related depression -- from its treatment -- SSRIs -- on neonatal outcomes."
The research team at the University of British Columbia, Vancouver, examined data for almost 120,000 live births between 1998 and 2001, and found 14% of the mothers who were diagnosed with depression.
The study compared the outcomes of babies born to depressed mothers treated with SSRIs and of those born to depressed mothers who were not treated, and there was a significantly greater incidence of respiratory distress, 13.9% vs 7.8%, and longer hospital stays for infants born to mothers on SSRIs, the team reported in the Archives of General Psychiatry.
Birth weight and gestational age were also significantly less in SSRI infants, and a significantly greater proportion were born before 37 weeks. "These findings are contrary to an expectation that treating depressed mothers with SSRIs during pregnancy would be associated with lessening of the adverse neonatal consequences associated with maternal depression," Dr Oberlander told Reuters.
Preterm birth is the leading cause of infant mortality in the US, accounting for at least a third of all infant deaths in 2002, and the contribution of prematurity to infant mortality may be twice as high as originally estimated, according to Dr William Callaghan and colleagues in the October 2006 Pediatrics journal.
For the study, the researchers looked at the top 20 causes of infant deaths in 2002 and found that 34% of the deaths occurred in preterm infants, 95% of whom were born before 32 weeks gestational age and weighed less than 3.3 lbs. Two-thirds of the deaths in preterm infants occurred in the first 24 hours of life, the research team found.
The fact that SSRIs are highly addictive also adds to the health risks that a pregnant woman faces if she is already taking Zoloft. "A lot of these medicines are associated with withdrawal syndromes, which can be very problematic for many patients, so stopping is something that needs to be monitored carefully by your doctor," said Dr Sandra Kweder, deputy director of the FDA's Office of New Drugs, in a March/April 2006 update on the FDA's Web site.
But on the flip-side of the coin, continuing to take Zoloft places the infant at risk for withdrawal. A February 2006 study in the Archives of Pediatrics & Adolescent Medicine reports that nearly one-third of infants born to women taking SSRIs show symptoms of withdrawal including tremors, high-pitched crying, gastrointestinal problems and sleep disturbances. The researchers found that 13% of the 60 newborns exposed to SSRIs exhibited severe symptoms of withdrawal.
An earlier study in the February 2004 Pediatrics journal found abnormal heart rhythms, sleeping patterns, and levels of alertness in babies exposed to SSRIs in the womb. Dr Philip Zeskind, a professor of pediatrics at the University of North Carolina-Chapel Hill, and lead author, referred to the results as alarming.
The researchers compared one-day-old babies of mothers who took SSRIs with babies of mothers who did not and looked at sleeping and waking patterns, movements and heart rates. According to the study, infants exposed to SSRIs tended to be locked in one "sleep state" and showed "fewer of the smooth and predictable changes in heart rate that normally occur in newborn infants."
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Critics also say, an important point to consider when weighing the risks and benefits of taking Zoloft during pregnancy, is that most experts who have evaluated all the clinical data on SSRIs say the benefits of the drugs are minimal.
In the July 2005 British Medical Journal, Moncrieff & Kirsch state in part: (1) Recent meta-analyses show [SSRIs] have no clinically meaningful advantage over placebo; (2) Methodological artifacts may account for the small degree of superiority over placebo; and (3) Given doubt about their benefits and concern about their risks, current recommendations for prescribing antidepressants should be reconsidered.