(Reuters Health) - - Pregnant women who take drugs like Ritalin and Concerta for attention deficit hyperactivity disorder (ADHD) are more likely than those who don’t to have babies with heart deformities and other birth defects, a recent study suggests.

Researchers examined data on more than 1.8 million pregnancies in the U.S., including 2,072 women who used methylphenidate (Ritalin, Concerta, Daytrana) and 5,571 who took an amphetamine (Adderall) during their first trimester.

Overall, women who took methylphenidate were 11 percent more likely to have a baby with birth defects and 28 percent more likely to have infants with heart malformations than women who didn’t take stimulants for ADHD during pregnancy.

There was no increased risk of birth defects in general or heart malformations specifically with amphetamines like Adderall, the researchers found.

“Our findings suggest that there might be a small increase in the risk of cardiac malformations associated with intrauterine exposure to methylphenidate,” said lead study author Krista Huybrechts of Harvard Medical School and Brigham and Women’s Hospital in Boston.

“Although the absolute risk is small, it is nevertheless important evidence to consider when weighing the potential risks and benefits of different treatment strategies for ADHD in young women of reproductive age and in pregnant women,” Huybrechts said by email.

An estimated 3 percent of children, teens and adults have ADHD, researchers note in JAMA Psychiatry. Stimulants like Adderall and Ritalin are among the most commonly prescribed medications for the condition, and these drugs are increasingly being used by women of childbearing age.

All of the women in the current study had health insurance through Medicaid, the U.S. benefits program for the poor.

Among children of women who were not taking stimulants for ADHD, 35 out of every 1,000 babies had birth defects, compared with 46 out of every 1,000 infants born to women using drugs like Ritalin.

To assess whether these results were unique to the U.S. or to women on Medicaid, researchers also examined health registry data for more than 2.5 million pregnancies in Denmark, Finland, Iceland, Norway and Sweden.

In the Nordic data, drugs like Ritalin were also associated with a 28 percent higher risk of heart malformations in babies.

The study wasn’t a controlled experiment designed to prove whether or how specific ADHD drugs might cause birth defects.

Because the study only included live births, it didn’t explore whether the drugs might increase the risks of severe birth defects that lead to miscarriage or stillbirths or that prompt women to terminate pregnancies, the authors note.

“If a woman has mild symptoms, it might be possible to avoid use of the medicine during pregnancy,” said Dr. William Cooper, a researcher at Vanderbilt University Medical Center in Nashville, Tennessee, who wasn’t involved in the study but wrote an accompanying editorial.

“However, if the woman has severe symptoms that interfere with her daily function, the results of this study can help to guide decisions on whether to continue,” Cooper said by email.

It may also make sense for some women with ADHD to consider stopping or changing medications when they’re trying to conceive, Huybrechts said.

“Considering the high rate of unplanned pregnancies among young women, the potential for accidental exposure is also very high,” Huybrechts said. “Although the absolute risk is small, it is nevertheless important evidence to consider when weighing the potential risks and benefits of different treatment strategies for ADHD in young women of reproductive age and in pregnant women.”

SOURCES: bit.ly/2m33rry and bit.ly/2qubOB0 JAMA Psychiatry, online December 13, 2017.