California's risky trend: an over-40 baby boom

Prematurity is the leading cause of infant mortality in the United States, accounting for more than a third of all infant deaths, according to the CDC. Even those born just a few weeks early -- from 34 to 36 weeks -- are six times more likely than full-term babies to die during their first week, according to a study by the March of Dimes published in the November Journal of Pediatrics.

These babies are also at greater risk of breathing problems, feeding difficulties and trouble regulating body temperatures, Fleischman said. Extremely premature babies are more likely to have developmental problems, from minor to severe retardation, and to be disabled.

Among the complications that concern Fleischman most are those posed by multiple births.

Older women are more likely to conceive twins or triplets naturally as well as to use fertility treatments that result in multiple births, he said. And multiple births -- twins, triplets and higher-order multiples -- in turn increase all the other complications of pregnancy. According to the CDC, among all women using assisted reproductive technology, 15% of single births, 64% of twins and 98% of triplets or higher-order multiples were premature.

"I don't think [women] believe it's going to happen to them," Fleischman said. "I don't believe they are well-informed sometimes by their obstetricians and their general physicians about the risk."

The March of Dimes strongly recommends pre-conception counseling for older women, and if they decide to proceed with pregnancy, to have their obstetrician assess their risk of diabetes and high blood pressure. Before trying to conceive, the agency recommends that women get in the best physical shape they can and take daily vitamins, including folic acid, which has been shown to prevent birth defects. If they are planning to use reproductive technology, they need to understand the risks involved with multiple births.

Some fertility experts believe that awareness of the risks is already rising -- and that the boom in over-40s births may have peaked.

"What I'm curious about is whether this trend is going to continue or whether it is in fact going to reverse," said Paulson, who directs the USC Fertility Clinic. "We've raised the consciousness of the population to the fact that the biological clock is a reality."

Rodi agrees. She had her two children at 32 and 34, earlier than many of her contemporaries. But then, she was a fertility specialist.

"I remember having to think very clearly, 'It's time to get married,' " she said.

Even so, she and her husband, who is also a physician, waited to begin a family for five years, until they had completed their medical training.

That's not the case for many fledgling doctors today.

"Women in residency programs are having children today," Rodi said, "once it became clear that you couldn't postpone having children forever."

mary.engel@latimes.com