WEDNESDAY, April 6, 2016 (HealthDay News) -- Despite initial concern from early studies, taking the epilepsy drug lamotrigine (Lamictal) during pregnancy may not raise the risk for certain birth defects, a large new study finds.

"An initial study of this drug showed an increased risk for cleft lip or cleft palate, but a number of other studies since have not, and our previous study showed an increased risk of clubfoot," said study author Helen Dolk, of Ulster University, in Northern Ireland.

However, the new study, which had "a much larger population size -- more than double the size of our previous study" -- has found no significant links, Dolk said in a news release from the journal Neurology.

The research, funded by the drug's maker, Glaxo Smith Kline, was published April 6 in the journal.

In addition to being prescribed to control epileptic seizures, lamotrigine is used to prevent mood swings in people with bipolar disorder, the study authors said.

Controlling epilepsy during pregnancy is important because seizures may harm the fetus, the researchers noted.

Dolk's team analyzed data on more than 10 million births over 16 years, including almost 227,000 babies with birth defects. Among those babies were 147 whose mothers took lamotrigine during the first trimester of pregnancy and had nongenetic birth defects.

Babies born with cleft lip, cleft palate or clubfoot were not significantly more likely than those with other birth defects to have been born to mothers who took lamotrigine in the first trimester of pregnancy, the study found.

In the general populations, one in every 700 babies is born with cleft lip or cleft palate, and nearly one in every 1,000 is born with clubfoot.

"We cannot exclude a small risk, but we estimate the excess risk of cleft lip or cleft palate among babies exposed to the drug to be less than one in every 550 babies," Dolk said.

"Since excess risks of cleft lip or palate have been reported for a variety of anti-epileptic drugs, we recommend that for all mothers with epilepsy, whatever their drug exposure, special attention be given to examining the baby for cleft palate," she added.