Expectant mothers who have a pre-pregnancy body mass index (BMI) of 40 have an increased risk of cesarean section (c-section) deliveries.

This new finding was published in the journal Acta Obstetricia et Gynecologica Scandinavica, and suggests that females with more than 16 kg (30 lbs.) weight gain during their pregnancy are at an elevated risk of requiring forceps, vacuum extraction, and C-section during childbirth.

The World Health Organization (WHO) has recently reported that 1.4 billion adults were overweight (BMI of 25-29.9) in 2008, and over half a billion were defined as obese (BMI of 30 or more).

These numbers show that obesity is a global health epidemic. From 2009-2010, the CDC reported that approximately one-third of adults in the United States were obese.

Previous studies carried out in Norway, like the current one, estimate that the rate of obesity among women who are of reproductive age has risen two-to three-fold in the last years.

Dr. Nils-Halvdan Morken from the University of Bergen in Norway and lead author of the current study said:

“Our study examines pre-pregnancy BMI and gestational weight gain on the mothers’ risk of operative delivery. With such alarming rates of obesity understanding its impact is an important health issue, particularly for women in child-bearing years.”

The investigators used data from volunteers involved in the Norwegian Mother and Child Cohort Study (MoBa0) – a population-based, prospective group of women who had children in Norway between 1999 and 2008.

The study was conducted by the Norwegian Institute of Public Health and consisted of a group of 108,000 children, 90,700 mothers and 71,500 fathers.

A sample of 50,416 women who gave birth to one baby were used in this study, and those who exhibited any of the following complications were excluded: gestational diabetes, placenta previa, diabetes, hypertension, and preeclampsia.

Outcomes revealed that obese and overweight women preceding pregnancy were at an elevated risk of C-section.

Expectant mothers with a pre-pregnancy BMI of 40 or more had the greatest risk of C-section, as well as an elevated risk of vacuum extraction delivery.

Investigators also revealed that women who gained 16kg or more while pregnant notably had a higher risk of requiring forceps, vacuum extraction, and C-section.

Obese women had a much lower gestational weight gain, however their children tended to be larger.

Dr. Morken concluded:

“Obesity and weight gain above 16 kg during pregnancy are independent risk factors for vacuum extraction delivery and need for C-section. While other factors may contribute to operative delivery and further investigation of gestational weight gain is warranted, it is important obstetricians be aware of the impact of a high BMI on pregnancy and delivery to properly advise women considering motherhood.”

Just yesterday, a study was released showing that C-section rates vary widely in hospitals across the U.S. The researches involved in the study recommended that maternity care and educational information regarding C-sections should be made more accessible to expectant mothers.

Written by Kelly Fitzgerald