Research shows that the use of topical corticosteroids during pregnancy does not increase the risk of birth defects.

Pregnant women have long been skeptical about using corticosteroid creams for psoriasis and other skin conditions out of fear of the unknown. They’d never been tested on pregnant women, and animal studies have shown some adverse birth effects.

A study published Thursday in JAMA Dermatology by doctors in Taiwan and the U.K. finally offers peace of mind. The study showed that potent topical steroids, used in an amount not exceeding 300 grams during the entire pregnancy, does not harm the unborn child or result in delivery complications.

In amounts higher than 300 grams, some low birth weights were recorded. Also, the National Psoriasis Foundation recommends that women who are pregnant or trying to conceive avoid the topical retinoid tazarotene.

Dr. Chi Ching-Chi, director of dermatology at Chang Gung Memorial Hospital in Taiwan, said the study took into account socioeconomic factors that could cause some women to have smaller babies.

He told Healthline that some women with severe skin conditions may need to use more than 300 grams of steroid cream during a pregnancy, but it would be uncommon.

In the case of psoriasis, symptoms usually improve during pregnancy. However, when nursing, women should never use topical steroids on or near their nipples.

Dr. Colby Evans, a Texas dermatologist and National Psoriasis Foundation board member, told Healthline that the new study provides badly needed clarification for doctors and patients.

“This has been very difficult to study, because you can imagine if you have 500 pregnant women and say, ‘We’re not sure what this will do to your baby,’ then nobody’s going to sign up for the study,” Evans said.

Instead, the researchers retrospectively examined health records from 10,000 pregnant women in the U.K.’s National Health Service. Evans noted that medical records are better kept in England than in the U.S. “Everything goes through one system,” he explained.

Evans said the study makes him feel better about prescribing topical steroids to pregnant women. “You always have had to say, ‘Look, we’re just not certain,’” he said.

Still, he said women should discuss any other risk factors for low birth weight with their doctor before using steroid medications.

Dr. Lawrence Green, a Washington, D.C. dermatologist, told Healthline that the study is good news for pregnant women, but confirms what had already been shown in clinical practice.

He said that he recommends pregnant women never use topical steroids over more than five percent of their bodies, and only on affected areas. Green chairs the research committee for the National Psoriasis Foundation.