Older moms' babies at greater risk

By Marilyn Elias
USA Today

The growing trend for women to postpone motherhood until their mid-30s or later is producing more low-weight newborns who are at risk for serious medical and learning problems, a new landmark study suggests.

The analysis, which covers all 283,956 infants born in Canada's Alberta province from 1990 to 1996, is believed to be the largest general population report on how a mother's age affects newborn weight and the chances of premature birth.

Babies weighing less than 5 pounds, 8 ounces or born before 37 weeks of pregnancy are more likely than heavier, full-term newborns to have learning disabilities, motor or language delays or health problems.

Newborns who weigh less than 2 pounds, 3 ounces tend to have the most serious disabilities, and most of them now survive, says Michael Speer, a Baylor Medical School neonatologist not involved in the study.

The report, published in Pediatrics magazine, shows that babies born to women 35 and older are:

• Twenty to 40 percent more likely than newborns overall to have a low birth weight.
• Twenty percent more likely to be born prematurely.
• Twenty percent more likely to be a twin or triplet.

In older moms, aging of the uterus and diseases such as hypertension may affect the fetus, says study leader Suzanne Tough of University of Calgary Medical School.

Older mothers tend to be wealthier and better-educated nonsmokers, "so to some extent, they may be compensating for these (biological) disadvantages with good medical care."

In 2000, 13 percent of U.S. births were to women 35 and older, up from 8.9 percent in 1990 and 4.6 percent in 1980, Centers for Disease Control and Prevention records show.

Among U.S. women giving birth, 6.4 percent age 35 to 54 have low-birth-weight infants. For mothers younger than than 18, 9.6 percent do, "so it's not that older women can't have healthy babies, and the younger, the better," says Joyce Martin, CDC spokeswoman.

Newborns are most likely to be a healthy weight if their mothers are in their 20s or early 30s, according to CDC figures. But 5 percent of mothers 35 and older have multiple births, 75 percent higher than the rate for those younger than 35, and many of these babies weigh too little, she adds.

"Older parents don't necessarily realize the risks, or they underplay them," Speer says. "Even if doctors told them, I'm not sure it would make a difference. We see women who postponed till 35, and they want to become pregnant now."

While most deliver healthy infants, very small babies "can cost a half-million dollars just to get out of the hospital," and new studies find "their intellectual capacity is much more compromised than previously thought," Speer says.