Researchers looking into increase in C-sections

Babies born by C-section are at increased risk for breathing difficulty.

Scripps Howard

With Caesarean sections heralding the arrival of about a third of babies in the United States and in other developed nations, researchers are struggling to understand why a greater percentage of women are having the procedure and the implications this may have for infants.

Although parental and physician convenience and obstetricians’ concerns over liability for vaginal-childbirth complications are cited as major forces driving the trend, there are many other factors.

One is that women are having children later, with reproductive systems less fit to handle the strain of natural delivery. Researchers at the University of Cambridge in England recently evaluated a half-million Scottish birth records from 1980 through 2005. They found that the number of women with a first pregnancy at age 35 and older had increased sevenfold, with 10 times as many women 40 and older giving birth at the end of the period than in 1980. And the Caesarean-delivery rate doubled during the 25 years.

Scientists also studied samples of uterine muscle taken from 62 older women having elective C-sections in Cambridge, and found that the older the women, the less able the muscles were to contract.

Other recent research has linked lower maternal vitamin D levels to greater C-section odds, and found that mothers who take maternity leave a month or so ahead of the due date have reduced odds.

It’s also apparent that C-sections performed before a baby is full-term are not a good idea. A study done last spring by the U.S. Centers for Disease Control and Prevention and the March of Dimes found that C-sections accounted for almost all the increase in pre-term births over a nine-year period.

In recent years, about one in eight babies born in the United States come early (before 37 weeks’ gestation). Premature birth is the leading cause of death for babies in the first month of life and contributes to more than a third of all infant deaths.

Babies born at 34 to 36 weeks’ gestation have a greater risk for breathing problems, feeding difficulty, trouble regulating body temperature, jaundice and delayed brain development than babies born full-term.

But another study, published earlier this month, suggests that even C-section births a week or two ahead of due dates pose more risk. The study looked at the experience of more than 13,000 single babies born in elective C-section procedures at 19 medical centers around the country. All the women had delivered a baby by C-section before. The researchers found that a third of those deliveries came at less than 39 weeks, but those infants were twice as likely to have health problems as those born more or less on time, and were at particular risk for breathing problems.

All babies born by C-section are at some increased risk for breathing difficulty compared with those born by regular delivery, because labor helps clear infants’ lungs of fluid.

Study authors said the findings clearly show that babies do better with a scheduled C-section done no sooner than seven days before a due date.

The official recommendation from government medical experts on childbirth is that women and their doctors should avoid C-sections unless there’s a clear medical reason for having one, and that repeat procedures should not be considered automatic for moms in good health.