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Pregnancy Over 35: What You Need To Know

By Julia Cruz
Beth Israel Deaconess Medical Center correspondent


As she cradles her two-month-old daughter Josephine, new mom Cibeline Sariano marvels at the tiny life she helped to create. At 38, Sariano waited to have children, instead focusing on her career as a fashion designer. When she and her husband decided it was time to start their family last year, they knew Sariano's age would make having a baby a challenge.

"It took a little time to conceive, and even when we did, I wouldn't allow myself to get too excited because I knew the risks," recalls Sariano.

Despite Challenges, Number of Older Moms on the Rise

Fertility peaks for most women in their 20s and begins a gradual decline in the late 20s. But at age 35, that decline picks up speed. According to the American Society for Reproductive Medicine, there is about a 20 percent chance of a 30-year-old woman becoming pregnant in any given month. For a 40-year-old, that number drops to just 5 percent.

Despite those statistics, and thanks to assisted reproductive technologies like In-Vitro Fertilization (IVF), the birth rate among women 40 to 44 years old is up six percent, according to the Centers for Disease Control & Prevention.

"I have so many patients who are over 35, over 40 and even a handful in their 50s," says Dr. Karen O'Brien, a high-risk pregnancy specialist in the Division of Maternal-Fetal Medicine at Beth Israel Deaconess Medical Center.

As a mother of three, Dr. O'Brien understands the struggles and risks of pregnancy over 35 well. She gave birth to her youngest child at age 36.

"I was nervous with my last, so I really sympathize with my older patients' concerns," she says.

Lowering Risks for Older Moms

After age 35, the chances for complications with a pregnancy significantly increase for both baby and mother. Expectant older moms are more at risk for miscarriage, preeclampsia (the development of high blood pressure and protein in the urine), gestational diabetes, ectopic pregnancy (where the fertilized egg implants in the fallopian tubes), Cesarean section, and even death.

"The maternal mortality rate in the U.S. is lower than in many other countries where access to health care is limited, but for American women over 35, it's still twice that of younger women," notes Dr. O'Brien.

Older moms-to-be are also more prone to multiple births (twins, triplets, etc.), and Cesarean sections, a procedure that, while common, still puts both mother and child at risk.

"It's really important that older women who are trying to conceive or are pregnant do whatever they can to optimize their general health," recommends Dr. O'Brien. "If you're overweight, you should try to achieve a normal body mass index prior to pregnancy. Avoid smoking or cut back, and avoid recreational drugs or alcohol."

For Cibeline Sariano, that meant losing weight.

"I was told that because my BMI was high," recalls Sariano. "So I went to a nutritionist and it helped. I lost 10 pounds and felt better."

Close Monitoring Reduces Risks for Babies

But even if an expectant older mom is perfectly healthy, the risks to her unborn child remain. Chief among those risks is aneuploidy, or an abnormal number of chromosomes, the cause of genetic disorders such as Down syndrome.

"The risks rise in relation to the age of the mother's eggs," Dr. O'Brien notes.

And the numbers are daunting. For a 20-year-old pregnant woman, the chance of having a baby with Down syndrome is 1 in 1,211 at 16 weeks. At age 35, that rises to 1 in 265; by age 40, it's 1 in 60 at 16 weeks.

"The older you are, the more likely it is to have a fetus with a chromosomal abnormality. That's the bad news," says Dr. Steven Ralston, Director of the Division of Maternal-Fetal Medicine at BIDMC. "The good news is the vast majority of babies are still normal and, for women who want information about the genetic health of their pregnancies, there are many tests we can do to both screen for and diagnose those chromosomal abnormalities."

Some expectant mothers choose tests such as amniotic fluid testing (amniocentesis) or sampling of the placental tissue (Chorionic villus sampling). But those are tests that are associated with a small risk of miscarriage. Now, newer tests with no risk of miscarriage are available to check for potential chromosome irregularities. For example, Cell Free DNA testing is a simple blood test that looks at the fetal genetic material circulating in an expectant mother's bloodstream.

"Cell Free DNA testing has a very high detection rate and no risk to the fetus," notes Dr. O'Brien.

Other tests can screen for genetic diseases even before a baby is conceived. Women undergoing in vitro fertilization (IVF) can have pre-implantation genetic diagnosis before the developing embryo is implanted in the uterus.

"Modern medicine has given us the tools to give outstanding care to older mothers, and with proper monitoring, most women over 35 have completely normal pregnancies," says Dr. Ralston.

The bottom line is that challenges exist for older women who want to have babies, but those challenges are not insurmountable.

"Couples shouldn't be so concerned about the risks that they don't complete their family," suggests Dr. O'Brien. "The vast majority of patients over 35 have very good outcomes, they just need a little closer attention paid to them."

New mom Cibeline Sariano says her daughter Josephine is living proof of that.

"I don't regret waiting," she says. "We've had a healthy happy baby and we're thrilled it all worked out."

Above content provided by Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.

Posted September 2012

Contact Information

Department of Obstetrics and Gynecology
Beth Israel Deaconess Medical Center
East Campus
330 Brookline Avenue
Boston, MA 02215
617-667-0475

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