MONDAY, June 18, 2018 (HealthDay News) -- Using the psychiatric drug lithium early in pregnancy may raise the risk of birth defects -- but not as much as previously thought, a large new study suggests.
Researchers found that women who used lithium during the first trimester were more likely to have a baby with a birth defect, compared to pregnant women who had a mental health disorder but did not take lithium.
But the absolute risk was lower than previous studies had suggested, said researcher Dr. Veerle Bergink, a professor at the Icahn School of Medicine at Mount Sinai in New York City.
Birth defects affected slightly more than 7 percent of children born to moms who used lithium during the first trimester. That compared with just over 4 percent of children in the group not exposed to lithium.
Experts said the findings offer women and doctors more information to use in making treatment decisions.
Lithium was approved in the United States almost 50 years ago. It is mainly used to treat bipolar disorder -- a mental health condition that causes severe shifts in mood, energy and ability to think clearly. People go through periods of depression and bouts of "mania," where they feel elated, but may also become irritable, reckless and impulsive.
Close to 3 percent of Americans have bipolar disorder, according to the National Alliance on Mental Illness.
For people with the condition, Bergink said, lithium is considered the most effective medication for stabilizing mood.
However, she explained, its use has been limited in pregnant women and women who might become pregnant.
That's because studies have linked the drug to a heightened risk of birth defects, such as malformations affecting the heart, particularly when it's used in the first trimester.
But a "major challenge" in that kind of research is separating the effects of medication from any effects of the underlying mental health disorder, said Dr. Katherine Wisner, a perinatal psychiatrist and professor at Northwestern University in Chicago.
The new study compared women who used lithium in the first trimester with women who also had bipolar disorder or depression but did not use the drug. The goal was to zero in on the effects of lithium itself.
Wisner, who was not involved in the research, called the findings "welcome and long overdue."
Wisner is a member of the Organization of Teratology Information Specialists. The group runs the MotherToBaby service, which provides research-based information on various pregnancy exposures.
The new findings are based on more than 22,000 women from six countries who gave birth between 1997 and 2015. All had a mood disorder -- including bipolar disorder or depression -- and 727 of them used lithium during the first trimester.
Overall, the study found, women on lithium did not have increased risks of any pregnancy or delivery complications.
But their babies were more likely to have a "major malformation" -- such as heart defects, neural tube defects (such as spina bifida) and malformations of the penis.
Those risks, however, must be weighed against the risks of stopping lithium, Bergink and Wisner said.
"The risks associated with lithium treatment must be balanced with the risks of relapse for women who require this drug to treat bipolar disorder," Wisner said. That relapse, she noted, may result in mania, depression, psychosis or self-harm.
Bergink said some options during pregnancy can include lowering the lithium dose, or going off the drug during the first trimester, then starting again -- all done under medical supervision.
There are other medications for bipolar disorder. But they may carry pregnancy risks, too. The drug valproate (Depakote), for example, should not be used, Bergink said. It carries a significant risk of serious birth defects like spina bifida.
Antipsychotic medications are another option. The evidence shows they do not carry a birth defect risk, Bergink noted. But they are typically not as effective as lithium, she said.
The bottom line, said Bergink, is that women should talk to their doctors about their treatment options before they become pregnant.
"That way, you'll have a good plan in place that will get you through your pregnancy," she said.
Those one-on-one discussions are crucial, Wisner agreed. "Each woman brings her unique illness course and values to the decision-making," she said.
The study findings were published online June 18 in The Lancet Psychiatry.
The National Alliance on Mental Illness has more on bipolar disorder.