HOUSTON --Last year, John Travolta's son Jett died after having a seizure. Now his wife Kelly Preston is expecting twins, at age 47. For some, women having babies in their late 40s comes as a surprise, but now it's becoming very common. Menopause no longer means the end of fertility. Linda Ames is 52. Her daughter Paloma was born when she was 42, her son Julian at 47 and her son Diego at 49. Paloma was born naturally. Infertility specialist Dr. Timothy Hickman helped Ames conceive Julian and Diego. "The only reason why I stopped having children was because my doctor recommended that after 50, it's probably not a good idea," she said. When is a woman too old to have a baby? "There used to be a recommended age that was put out by the American Society for Reproductive Medicine, which was the natural age of menopause, which is 50, 51," Dr. Hickman said. "So then it changed, and they've removed that statement because studies have shown that mothers have done well up to age 55." Hickman chose to limit infertility treatments at Houston IVF to age 55. "Theoretically a woman in her 90s could get pregnant. But she could go into labor, have a heart attack," Hickman said. Technology has made it possible. Women over 45 usually use eggs donated by young women and take hormone treatments. Hickman requires a medical checkup first. "We have them see a reproductive mental counselor, so they talk through issues, what it's going to be like to carry a baby, are they ready for this," Hickman said. Ten to 20 percent of his patients are over 40. Most delayed childbirth because of second marriages or careers. But their hearts go out to John Travolta and his wife Kelly Preston, who lost a child. At 47, Preston is expecting twins. "I'm extremely happy for them," Ames said. "And is she too old? No, I had a baby at 49, and I didn't think I was too old, so I think she's just the right age." For more information on infertility treatments for older women, visit The Society for Assisted Reproductive Technology website. The society is an organization of physicians who do infertility treatments and on its website, it compares success rates of clinics in cities and around the country.