For Marilyn Nolen, parenting came a little later in life than she expected. With the help of assisted reproductive therapy (ART) and donor eggs, she finally became the proud mother of twin boys -- when she was 55 years old.
Now 65 and raising her two rambunctious ten-year-olds in Killeen, Tex., Nolen is one of a growing number of women in the U.S. who have entered motherhood post-40.
While birth rates in 2008 dropped among women in their teens, twenties, and thirties, the 40-to-44 age bracket saw a 4 percent increase in birth rate, according to a report released Tuesday by the Centers for Disease Control and Prevention.
Birth rates increased for mothers over 45 as well, with the number of births among these women increasing by 4 percent in the past year. What's more, women over 40 were also more likely to be first-time mothers than in past years, the report found.
"This increase is part of a general trend that we've seen over the past few decades," says Brady Hamilton, lead author on the study and researcher for the CDC's National Center for Health Statistics. "A rise in reproductive technology gives women more options and more women are choosing to postpone childbirth or have a second or third child later in life," he says.
This doesn't mean it's easy to conceive in mid-life, however, warns Dr. Marjorie Greenfield, author of "The Working Woman Pregnancy Book" and director of general obstetrics and gynecology at University Hospitals Case Medical Center.
"Statistics like this encourage putting off pregnancy even more. It gives women the illusion that the biological clock doesn't really start ticking until later," she says, "but most births over 45 are from egg donors. The chance of getting pregnant without assisted reproductive therapy after age 40 is only 10 percent," she says.
Because of her age, Nolen wasn't able to use her own eggs. After nearly a decade of failed attempts with other fertility treatment, using in vitro fertilization with a donor egg and her husband's sperm was the only treatment that was finally successful.
The rise in new and better reproductive technologies -- like those the Nolens used -- explains, in part, why more women are willing and able to conceive at middle age, Hamilton says.
"Assisted reproduction therapy and fertility treatments are feeding this trend," says Dr. Richard Paulson, chief of the division of reproductive endocrinology at the University of Southern California, "but it would be hard to tell how many people are actively waiting to have children [because they can use this technology] and how many are older women wanting to have children that now can because of an increasing social acceptance of being an older mother and this technology."
Nolen and her husband Randy would fall into the second category, older parents who would say "life just kind of played out this way." Nolen was already over 40 when the two got married, so while they both wanted children, the opportunity to start a family together came later in life. But that family didn't come easily.