Feb. 10, 2012 -- Zoila Leiva was 4 ½ months pregnant with twins when her doctor delivered the devastating news: She had breast cancer. And it was advanced.

Ten months earlier, Leiva was told the lump in her right breast was benign -- a swell of fluid that would subside with time. Instead, the lump grew. And biopsies revealed it was a stage III tumor that had already spread to her lymph nodes.

"The oncologist said, 'The only way we can treat you, the only way we can save your life, is for you to have an abortion," said Leiva, who was 38 at the time, with a 14-year-old daughter. "I had two weeks to make a decision."

Chemotherapy drugs are toxic to tumors. And depending on the drug and the stage of pregnancy, they can harm fetuses, too. At her oncologist's request, Leiva attended an "abortion orientation" session that left her troubled after she learned about the three-day procedure to terminate her pregnancy.

"Those babies were already moving inside me," she said. "I couldn't do it."

Instead, Leiva looked for a second opinion and found an oncologist willing to start treatment right away.

Chemotherapy for breast cancer can be safe during the second and third trimesters of pregnancy, according to a new report in The Lancet. And terminating the pregnancy does not appear to improve the mother's prognosis.

"The situation remains challenging since in some situations an advanced cancer can be fatal for mother and fetus," said Dr. Frédéric Amant of the Leuven Cancer Institute in Belgium, lead author of the report. "The patient and her partner should be informed about the different treatment options and the physician should explain that termination of pregnancy does not seem to improve maternal outcome, but the decision to continue or end the pregnancy is a personal one."

In a separate study published in The Lancet Oncology, children whose mothers underwent chemotherapy during pregnancy were found to be normal on measures of general health, behavior and growth out to 18 years of age.

One week after her first round of chemo, Leiva's hair started to fall out. She hoped to hang on to some of it for her daughter's Quinceañera -- a Cinderella-themed birthday celebration with a 350-strong guest list.

"The stylist pulled off a miracle that day. My hair looked really good," she said. "It all came out the next day."

Over 12 weeks, Leiva had four rounds of chemo. During that time, she said the tumor shrunk to near nothingness. But the stress was hard to bear.

"It was a real rollercoaster," said Leiva. "But I would go to chemo, with my bald head and big belly, and I actually looked forward to it. It was nice having all those women around me."

Leiva's doctors said she was an inspiration to other breast cancer patients.

"Pregnant patients are warriors," said Dr. Jane Kakkis, Leiva's surgical oncologist and medical director of breast surgery at Orange Coast Memorial Medical Center in Fountain Valley, Calif. "Most pregnant women are more concerned about their child's life, but they also want to be around to care for their baby."

Kakkis said the goal in Leiva's case was to save three lives, which took a lot of team work.

"These patients need extremely individualized care and a lot of communication between the treatment team," she said.

Thirty-two weeks into her pregnancy, Leiva delivered two boys by C-section. Julian weighed 4 pounds, 3 ounces; Joel weighed 3 pounds 12 ounces.

"I had three high-risk obstetricians in my delivery room," said Leiva, alluding to fears that her preemies would be small and weak. "But they were breathing on their own, eating on their own. They were strong boys. And they're still strong boys."

Pregnant With Cancer: New Hope

After the birth, Leiva quickly started a second string of chemo treatments with a more aggressive and toxic combination of drugs. And when her boys were 6 months old, she had both breasts and 11 lymph nodes removed.

"I didn't want to risk it," Leiva said, explaining her decision to opt for the radical 13-hour surgery over the less invasive lumpectomy. "These babies need to have their mother for a long time."

After the surgery, she had six more rounds of chemo and seven weeks of radiation.

"I wasn't really able to enjoy them as baby-babies," said Leiva, whose babies are now 3 years old. "But I was always thinking about when I get better, when my boys get bigger, and how I was going to be around to see it all."

Although pregnancy does not increase the risk of breast cancer, the decision by some women to delay motherhood might be increasing the number of pregnant women with cancer, according Lillian Shockney, a breast cancer nurse at Johns Hopkins Hospital in Baltimore.

"We know age is a risk factor, and so is having your first child after age 30," said Shockney, who is also an associate professor of surgery, gynecology, oncology and obstetrics at Johns Hopkins University School of Medicine. Pregnancy also causes breast changes that can mask the signs of cancer, delaying the diagnosis.

"I think a key message for women having babies if they see something different about their breasts -- even if a doctor says, 'Oh, your breasts are going to change because you're pregnant' -- go to a breast center for a clinical exam," she said. "Changes in one breast, not both, are a classic sign that something's wrong. Follow your instincts."