Kim Harper started a career before starting a family. After graduating from Michigan State University in 1990, she traveled, earned a law degree and began working as an attorney. When Harper married in 2006, she and her husband, Jeff, hoped a baby would soon follow.
"We didn't marry until I was 38," Harper says, "and we always knew we didn't have a lot of time to waste."
A year passed; no baby.
Like many women who marry later in life, Harper didn't think much about her fertility until she'd reached the age at which many doctors warn that healthy pregnancies don't come easily.
"What a lot of women do not know is that we are born with all of the eggs that we are going to get. And a lot of those eggs are used before we get out of puberty," says Kim Hahn, founder and CEO of Conceive magazine. "We are not like men; we do not regenerate eggs."
Concern about her age prompted Dawn Crowley's doctors to encourage her to get pregnant even before her planned marriage.
"When I told my doctor we wanted to have children after we married, she looked at me and said, 'I understand the need to be married, but you're 38 years old. I suggest you try right now,'" recalls Crowley, who is now 40.
The Birmingham, Mich., resident married Jim Crowley, 50, in August 2007. They gave birth to a healthy 7 1/2-pound girl, Kate, six months later.
The statistics might surprise some women:
At 20, the odds of getting pregnant when everything is timed perfectly are about 25 percent per cycle. By age 30, the odds drop to 10 percent to 15 percent each month, and by age 40, it's 5 percent, reports Conceive magazine.
Women who get pregnant between the ages of 35 and 45 face a 20 percent to 35 percent chance of miscarriage, according to the American Pregnancy Association. That's on top of common complications such as high blood pressure and gestational diabetes.
By the time a woman is 43, the risk of having a baby with chromosomal abnormalities such as Down's syndrome rises to 1 in 50, from 1 in 1,500 at age 20, according to pregnancyinfo.net
At age 35, the rate is 1 in 350.
The rate of in-vitro fertilization has increased 17 percent from 2003 to 2007, with the greatest increase seen among women ages 35 to 37, according to the Society for Assisted Reproductive Technology. But age also seems to play a role in the success of the procedure. Younger women - those younger than 35 - have about a 40 percent chance of having a live birth with IVF. By the time a woman is 42, the live birth rate with IVF drops to about 11%.
Children born to older parents are more likely to develop autism. That's especially true for first-born kids, according to a study in the December issue of the American Journal of Epidemiology. Also, a Swedish study in the American Journal of Psychiatry found that children with fathers older than 45 were twice as likely to develop schizophrenia.
The trend of women having babies later in life shows no sign of slowing down. The National Center for Health Statistics reports that the percentage of women giving birth for the first time at age 35 or older has increased eight-fold since 1970 - from 1 percent to 8 percent.
The birth rate among women ages 30 to 34 grew 2 percent from 2006 to 2007. Among women 40 to 44, the birth rate grew 1 percent to 9.5 births per 1,000 women - one of the highest rates ever.
"It makes sense that women are waiting longer to start families - college, careers, not meeting the right person earlier in life," says Dr. Kristen Wuckert, an ob-gyn at Mission Obstetrics and Gynecology in Warren, Mich. Years ago, she says she might have seen an older woman once a week; now it's a daily or twice-a-day occurrence.
"Another reason women wait is because they can. We have a lot more options, albeit expensive ones, to help in getting pregnant. It has also become more the norm than the exception.
"We see celebrities in their 40s and older doing it - why not us?"
Gwen Coles of Bloomfield Township, Mich., turned to artificial insemination when she was 39 and still single.
"My biological clock was ticking and I was tired of waiting for Mr. Right," says Coles. After the fourth try - when she had nearly given up - it worked.
Twins - a boy, Brandon Kaleb, and a girl, Michelle Ashley - are now 14.
"I feel so blessed to have them," says Coles, a retired Detroit police lieutenant.
Men are not immune to the effects of aging, either, says Dr. Ronald
Strickler, a reproductive endocrinologist with Henry Ford Hospital. "Older men are more likely to have problems that interfere with sperm production," he says.
Illnesses such as diabetes, hypertension, and hyperlipidemia also contribute to erectile dysfunction, he says.
"The decline ... is not associated with an event as happens when women experience menopause; rather, it is silent. It can begin in the 40s or wait until the 70s."
For couples like the Harpers of Southfield, Mich., it's all about timing. Sometimes life's stages are out of sync with biology.
Because pregnancy wasn't happening quickly, Harper was referred to a maternal fetal medicine specialist at Beaumont Hospital for a battery of tests. The tests showed that her reproductive health was fine, and six months later she was pregnant.
But Harper's was not a trouble-free pregnancy. She developed gestational diabetes in her first trimester, which can lead to jaundice, respiratory distress and low blood sugar and excessive weight in babies.
Jeff Harper, a 42-year-old engineer for The MathWorks in Novi, Mich., admits that he wouldn't let himself get too excited during his wife's pregnancy. "People younger than us wind up losing a baby; with our age I knew the odds were even higher," he says. "My overall philosophy is to hope for the best, but prepare for the worst."
But for the Harpers, ultimately the best prevailed. A healthy, 7-pound Katherine Anne Harper was born Jan. 18.
"She was tiny and beautiful and perfect! Her cry was like music to my ears," Kim Harper says. "I still thank God every day for my amazing little miracle!"
Halle Berry was 41 when she and Gabriel Aubry, 32, had Nahla Ariela Aubry on March 16, 2008.
Salma Hayek was 41 when she and Francois-Henri Pinault, 45, had Valentina Paloma Pinault on Sept 22, 2007.
Naomi Watts, then 38, and Liev Schreiber, 39, had Alexander (Sasha) Pete Schreiber on July 25, 2007.
Nicole Kidman was 41 when she and Keith Urban, 40, had Sunday Rose Urban on July 7, 2008.
Jennifer Lopez, then 38, and Marc Anthony, 39, welcomed twins Max and Emme Muniz on Feb. 22, 2008.
Marcia Cross was 44 when she and Tom Mahoney, 49, welcomed twins Savannah and Eden Mahoney on Feb. 20, 2007.
Jane Hajduk, then 42, and Detroit native Tim Allen, 55, had Elizabeth Allen on March 28, 2009.
FERTILITY AND AGE: WHAT WOMEN SHOULD KNOW
Women are born with a finite number of eggs. As they age, the quantity and quality of the eggs decline, which may make conception more challenging.
Here's advice from Conceive magazine on how to maximize your fertility:
IN YOUR 20s
Research how your method of contraception affects conception. The effects of several contraception methods can delay conception four months or more.
Get tested for STDs like chlamydia and gonorrhea, which can damage reproductive organs if left untreated.
Stop smoking, and avoid alcohol and recreational drugs.
Maintain a normal weight. Being over- or underweight can make it harder to conceive.
Start taking a prenatal vitamin. Experts recommend that women of childbearing age take 400 micrograms of folic acid daily.
If you have not conceived in 12 months, consult a doctor.
IN YOUR 30s
Try not to stress out; stress itself does not impede conception directly, but high levels of stress can halt menstruation or make menstrual cycles longer.
Get familiar with your optimal fertility period. If you have a 28-day cycle, you probably ovulate around day 14, so you should have sex on days 10, 12 and 14. If your cycle is not regular, you should start earlier and continue later.
If you have not conceived in 6 months, consider seeing a fertility specialist.
IN YOUR 40s
Be proactive; consult a fertility specialist.
Get pre-screened for potential risks like silent diabetes and hypertension.
Learn your mother's menopause history. If she entered menopause in her mid-40s, chances are you will too.
Ovulation induction: Medication is administered to cause the release of more eggs at one time. Typically, when fertility difficulties are suspected, this is a first approach.
Cost: $100 to about $3,000 or more.
Intrauterine insemination (IUI): Semen is collected and inserted through the vagina and cervix into the uterus with a catheter. Often combined with ovulation induction.
Cost: $1,000 to $2,000.
In-vitro fertilization: Eggs are harvested from the mother; then eggs and sperm from a partner are combined in a lab. The fertilized egg is placed back into the woman's body to develop. This can be done using a donated egg or donated sperm.
Cost: At least $10,000 to $15,000.
Gamete intrafallopian tube transfer (GIFT): After ovulation, eggs are harvested from the mother. Sperm and egg are placed beside one another in a woman's fallopian tube in hopes that fertilization will occur.
Cost: $15,000 to $20,000.
Embryo adoption: A fertilized egg from one couple is "adopted" by another couple and then implanted for development. Cost: $6,000 to $18,000.
Source: Cost estimates from "Budgeting for Infertility," by Evelina Weidman Sterling and Angie Best-Boss, researchers on fertility matters. Their Web site is www.myfertilityplan.com.