By Val Willingham
CNN Medical Producer

I'm not wild about babies. Don't get me wrong – it's not that I dislike them – I'm just not like a lot of my female friends who oooh and ahhh every time an infant enters the room. But I wanted to be a mom, so in my early 30s I did have a child. A beautiful little girl, who, even at the age of 21, still is my baby. My husband and I wanted our daughter. She was planned. We started thinking about having a child in September 1986. She was born in July 1987. We were blessed, and if you look at statistics, we also were lucky.

According to the American Fertility Association more than 15 percent of couples in the U.S. have difficulty conceiving a child. Many people are delaying having children – about 20 percent of women in the United States now have their first child after age 35. And as we age, it becomes more and more difficult to conceive. According to Dr. Robert Stillman, director of the Shady Grove Fertility Reproductive Science Center in Rockville, Maryland, "It's just the natural aging process, and women can make that worse by smoking, alcohol abuse, excessive weights - both high and low."

In her 30s and 40s, a female's reproductive cycle begins to change. As a woman ages, her eggs are more likely to develop abnormalities The probability of having a baby drops between 3 and 5 percent per year after the age of 30, a rate that can be even higher after 40. In fact a woman in her 40s faces a 50 percent risk of suffering from a miscarriage, and there can be other problems. "As women age, they can end up with uterine problems, such as fibroid tumors, ovarian cysts or growths endometriosis," Stillman adds. Many couples turn to expensive, state-of-the-art procedures such as in-vitro fertilization in order to have children.

When women get into their 50s, typically menstruation and ovulation cease with menopause. But you wouldn't necessarily know that by looking at Hollywood. Many stars are having kids well into midlife. Stillman says there is nothing wrong with that, but many older people come into his office wanting to get pregnant with their own eggs, because aging Celebrity X just had twins. Stillman knows that's not possible and says these actresses need to be honest. He feels it's frustrating. "If they are going to be on the cover of People, they have a responsibility to their following, not to mislead people that fertility is easy at 52. It's not. They are (using) donor eggs."

So yes, there really is a biological clock. And while it keeps tick, tick ticking, couples need to think about their odds when it comes to having little ones later in life.

Are you thinking of having a child? Are you having problems? Are you someone who was successful giving birth at a later age? Tell us your story. We'd like to hear about it.

Editor’s Note: Medical news is a popular but sensitive subject rooted in science. We receive many comments on this blog each day; not all are posted. Our hope is that much will be learned from the sharing of useful information and personal experiences based on the medical and health topics of the blog. We encourage you to focus your comments on those medical and health topics and we appreciate your input. Thank you for your participation.