Obese women more likely to have pregnancy complications and caesarean sections than women of average weight

Obese and morbidly obese women are more likely to have pregnancy complications and caesarean sections than women of average weight, according to a new study by physician-scientists at NewYork-Presbyterian Hospital/Columbia University Medical Center and published in the April American Journal of Obstetrics and Gynecology. The controlled study is one of the largest ever to look at obesity in pregnancy, following more than 16,000 pregnant women at 14 medical centers across the country.

Compared with women of normal weight, obese and morbidly obese pregnant women were at greater risk for gestational hypertension (2.5x and 3.2x, respectively), preeclampsia (1.6x and 3.3x), gestational diabetes (2.6x and 4.0x), fetal birth weight greater than 4,000 grams (1.7x and 1.9x), and fetal birth weight greater than 4,500 grams (2.0x and 2.4x), the study finds.

Additionally, for women who had not yet given birth (nulliparous), the cesarean delivery rate was 20.7 percent for the control group, compared with 33.8 percent for obese women, and 47.4 percent—three times more likely—for morbidly obese women.

“The increased risk of cesarean section is concerning because complications related to surgery are more frequent in obese women,” says Dr. Mary D’Alton, gynecologist and obstetrician-in-chief at NewYork-Presbyterian Hospital/Columbia and chair of Obstetrics and Gynecology and director of Maternal Fetal Medicine at Columbia University College of Physicians & Surgeons. “As a result of this study, obese and morbidly obese patients now have access to more precise information about their health risks during pregnancy” says Dr. Fergal Malone, director of Ultrasound and associate professor in the Department of Obstetrics of Gynecology at Columbia University College of Physicians & Surgeons.

Risks associated with hypertension and preeclampsia include seizures during labor, intracranial bleeding, liver rupture, bleeding, poor fetal growth, and stillbirth. Gestational diabetes is associated with risk of a fetus that is too large to easily fit through the birth canal, risk of a fetus that gets stuck during delivery (shoulder dystocia), and risk that the newborn baby will have very low blood sugar (hypoglycemia)—which, if unrecognized, can lead to newborn seizures. A fetus size greater than 4,000 grams is also a risk for shoulder dystocia.

The data was obtained from patients over a short time period—1999 to 2002—and therefore represents an accurate snapshot of the state of this issue in contemporary practice, says Dr. D’Alton. The study, which followed women enrolled in the multi-center First and Second Trimester Evaluation of Risk (FASTER) trial, included 13,752 control patients, 1,473 obese patients, and 877 morbidly obese patients. Subjects were divided into three groups: body mass index (BMI) of less than 30 (control), 30 to 34.9 (obese), and 35 or greater (morbidly obese)— criteria defined by the Institute of Medicine. Groups were compared using univariate and multivariable logistic regression analyses.

Since 1991, there has been a 50 percent to 70 percent increase in the rate of obesity in adults of reproductive age. Approximately one-quarter to one-third of the U.S. population is obese. Obesity has long-term health implications such as uterine cancer, diabetes mellitus, and heart disease.

The lead author, Dr. Joshua Weiss was a fellow in the Division of Maternal Fetal Medicine at NewYork-Presbyterian Hospital/Columbia and currently practices maternal fetal medicine in Dallas, Texas.  In addition to Dr Weiss, the NewYork-Presbyterian Hospital/Columbia study was authored by Dr. D’Alton; Dr. Malone;. Dr. Robert H. Ball; Dr. David A. Nyberg; Dr. Christine H. Comstock ; Dr. George Saade; Dr. Keith Eddleman; Dr. Sabrina D. Craigo; Dr. Stephen R. Carr; Danielle Emig, MPH; and Suzanne M. Carter, MS.

The FASTER trial, sponsored by the National Institute of Child Health and Human Development (NICHD), is a prospective multi-center investigation of singleton pregnancies from an unselected obstetric population.

On February 9, 2004, at the annual meeting of the Society for Maternal-Fetal Medicine, Drs. Mary D’Alton and Fergal Malone presented the first findings from the FASTER trial, demonstrating that ultrasound measurement of fetal-neck-fold thickness, together with a measurement of biochemical markers, is an effective test for Down Syndrome in the first trimester. http://www.cumc.columbia.edu