A new study has found that the rate of certain health complications is higher for some types of birth as compared to others.

How a mother gives birth can determine the likelihood she’ll have health complications, according to new research.

Women undergoing their first cesarean delivery have a higher rate of intensive care unit (ICU) admission compared to women who give birth vaginally or have a repeat cesarean, according to a new study from the Centers for Disease Control and Prevention (CDC).

Researchers compared the incidence of four “maternal morbidities” (health complications associated with labor and delivery) in a new study from the CDC National Center for Health Statistics, the CDC National Vital Statistics System, and the U.S. Department of Health and Human Services.

The safest way to give birth, according to the study, is vaginally. Women who gave birth by vaginal delivery with no previous cesarean delivery had the lowest rate of the four studied complications.

The complications were a ruptured uterus, unplanned hysterectomy, ICU admission, and maternal blood transfusion.

Maternal blood transfusion is the most common of the four complications, occurring at a rate of 280 times per 100,000 births, according to the study. ICU admission is next, at 154 per 100,000, followed by unplanned hysterectomy — removal of the uterus — at 40 out of 100,000, and a ruptured uterus, at 26 per 100,000.

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Primary cesarean deliveries led to the highest rates of transfusions, at 525 per 100,000. Those surgeries led to 383 ICU admissions per 100,000 births.

Repeat cesareans led to the highest rates of ruptured uterus, at 89 per 100,000, and unplanned hysterectomies, at 143 per 100,000.

“We were somewhat surprised that, for two of the four morbidities, the highest rates were for primary cesarean deliveries and not repeat cesarean deliveries,” said study co-author Sally Curtin, a health statistician at the National Center for Health Statistics.

Researchers were surprised because previous cesarean delivery has been shown to be an independent risk factor for complications.

“Obviously, some cesareans are necessary and lifesaving, but there are more health risks associated with these births,” Curtin said.

The differences in maternal morbidity can be explained slightly by the age of the mother because older women have a higher chance of having a cesarean, according to the study. The total cesarean rate for women between the ages of 35 and 54 is nearly twice that of women under the age of 20.

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Complication rates also varied depending on race.

Non-Hispanic white women have the lowest total cesarean rate. Hispanic women have the lowest primary cesarean rate but the highest proportion of repeat cesareans, according to the study.

This study adds to a large volume of previous work that shows more frequent complications for cesarean versus vaginal delivery, Curtin said.

“However, we show that having that first cesarean means more morbidity now,” she added, “and also sets them up for more morbidity in future pregnancies.”

Data for this study was collected from birth certificates from 41 states and Washington, D.C., in 2013.

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