Aug. 30, 2010 -- Cesarean section deliveries are at an all-time high in the U.S. and are expected to keep rising, and new government-funded research may help explain the trend.
Nearly one in three babies are now delivered surgically -- up from one in five just over a decade ago.
Previously recognized contributors to the rise include delayed childbearing, the rising obesity rate among moms-to-be, and an increase in multiple birth deliveries.
Induced Labor and C-Sections
The new analysis also found that longer labor times and an increase in induced labors are also factors.
And a sharp decline in attempted vaginal deliveries in women who have had previous C-section deliveries has certainly contributed to the trend, government investigators said Monday.
Researchers from the National Institute of Child Health and Human Development analyzed data from more than 228,000 deliveries at 19 hospitals across the U.S. from 2002 to 2008.
Among their findings:
- One in three first-time moms delivered by C-section.
- Previous surgical birth was the most common reason for C-sections, accounting for almost a third of all cesarean deliveries.
- The C-section rate among older moms was double that of younger ones.
- 44% of women who attempted vaginal delivery had labor induced, and the C-section delivery rate was almost twice as high in these women as in women whose labor was spontaneous (21% vs. 12%).
The induced labor rate among the women in the study was much higher than has been seen in previous studies.
Doctors' Role in C-Section Rates
In the study, half of all C-section deliveries to women whose labors were induced were performed before cervical dilation had progressed to 6 centimeters in diameter. That suggests that "clinical impatience" may have played a role, the researchers note.
"One message from this study is that physicians should use induction more judiciously," study researcher Jun Zhang, MD, PhD, tells WebMD. "Another message is that they should probably slow down."
While the conventional wisdom has been that the active phase of labor begins at a cervical dilation of around 4 centimeters, Zhang says recent research suggests the active phase can start as late as 6 centimeters for some women.
Only about a third of women who had a previous cesarean delivery attempted vaginal delivery, known as VBAC. Their success rate was just under 60%, meaning that roughly one in five women who had had a previous surgical delivery achieved a vaginal birth.
The number was lower than the 60% to 80% rate found in some other studies, Zhang says.
Zhang says too few women who desire VBAC deliveries are being offered them because many ob-gyns and medical facilities have stopped performing the procedures.
About one in 10 planned surgical deliveries was performed in women who had no obvious medical reason for having a C-section, but it was not clear if these were cases of "C-section on demand" by the patient.
The high rate of C-section deliveries among first-time moms was not easily explained, the researchers say.
But this trend is likely to drive surgical delivery rates even higher in the future, especially if VBAC deliveries continue to decline, according to the researchers.
The report was published today online in the American Journal of Obstetrics & Gynecology.