A new study billed as the most extensive analysis of pregnancy and birth outcomes among women 40 and older suggests that medical complications and interventions during delivery are more prevalent than previously believed.
The most significant finding, the researchers said, was that women who first gave birth in their 40s were twice as likely to have a caesarean section as were first-time mothers in their 20s.
Forty-seven percent of the first-time mothers in their 40s had a caesarean section. That exceeds the 35% rate for that age group cited in previous studies and is more than double the 22% national average for women of all ages.
In the study of 24,032 California women in their 40s who gave birth in 1992 and 1993, the rates of pregnancy-related diabetes and high blood pressure also were substantially higher than in a comparison group of 625,525 women in their 20s who had children.
The work is being published today in the journal Obstetrics & Gynecology.
One of the largest differences between the older and younger mothers was in gestational diabetes, a serious complication of pregnancy that affected about 7% of the older mothers, regardless of whether the baby was their first. That rate was about four times higher than that of the younger mothers.
"This is the first time accurate numbers can be attributed to some of the complications of labor and pregnancy" for the older women, said the study's lead author, Dr. William Gilbert of the UC Davis School of Medicine.
In addition, the new research found that labor was somewhat more difficult and more prolonged for the older women than the younger ones, and their babies were more likely to be born prematurely or be underweight, the study found.
But despite such added risks, the researchers strongly cautioned that the study results should not deter women in their 40s who want to have children.
"The take-home message is that while a lot of complications of labor and pregnancy are increased [for women in their 40s], the vast majority of them do perfectly fine," said Gilbert.
Susheela Singh, director of research at the Alan Guttmacher Institute in New York, a think tank for reproductive issues, said earlier studies may have underestimated birth and pregnancy complications for older women because they included women in their 30s.
