Dr. Gary Goldenberg, assistant professor of dermatology and pathology at Mount Sinai School of Medicine, said women in their childbearing years must be particularly careful about using oral and topical retinoids, which are commonly used and highly effective.
"They are not safe, and an important question to ask a female patient is if she is pregnant or planning to have a baby or breastfeed," he said.
"Some of the scientific evidence is that it can harm the fetus or the baby of a nursing mother. Even though the medicine may be safe, do you really want to take a chance?"
He advises patients to go off oral retinoids a month before planning a pregnancy, two months beforehand with oral therapies.
"The question is, what will happen to my acne once I am pregnant or nursing?" said Goldenberg. "Basically, we don't know the answer."
About a third of patients stay the same, a third get better and a third get worse, he said.
One promising new treatment is the use of blue light. Once a week for six to eight weeks, a patient sits in a machine with goggles to protect their eyes as a the visible light penetrates the skin and eventually dries out the acne.
One of Goldenberg's patients, who is pregnant, has had remarkable results.
A 29-year-old medical fundraiser from New York, Lucy started noticing her acne when she was in her 20s.
"The biggest challenge for me is I am fair-skinned," said Lucy, not her real name. "I happen to have the cystic type and it leaves a pink mark on my skin that can literally take years to go away.
"When you have one or two, it's not that bad. But when it happens every month, it leaves marks on the skin."
Twice, she was treated with the retinoid Acutane, and it helped clear her skin, but when she decided to start a family, she had to find an alternative treatment.
"I did six sessions of blue light therapy and it's been quite dramatic," she said.
Not surprisingly, the most common patients Goldenberg sees in his practice are adult women. "We are doing a survey on adult acne and we needed 100 patients and it didn't take long," he said.
The statistics represent a great frustration to women like Lucy. "In your 30s, you think you should be done with this," she said.
Diane Lang, a 42-year-old education counselor from Morris County, N.J., agrees.
"I have tried creams, gels, antibiotics and even blue light and now I'm doing peels and laser," she said. "At my age, you don't expect acne. I feel like we have enough to worry about with gray hair, wrinkles, changes in our body and now acne. It's horrible."