Weight Gain in Pregnancy Is Key Risk Factor for Large Infants

Jenni Laidman

March 06, 2014

Excess maternal weight gain during pregnancy appears to be the greatest single contributor to large-for-gestational age (LGA) births, according to a study published online March 4 in Obstetrics & Gynecology.

To determine the effect of each of several risk factors for LGA births, Shin Y. Kim, MPH, from the Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia, and colleagues analyzed 660,396 singleton deliveries in Florida from 2004 to 2008, using birth certificates and linked hospital discharge data.

They analyzed the contributions of prepregnancy body mass index (BMI), gestational weight gain, and gestational diabetes mellitus in the occurrence of LGA births. They estimated the contribution of each factor individually and combined by race and ethnicity, adjusting for maternal age, nativity, and parity. An infant is considered large for gestational age if his or her weight is at or above the 90th percentile for gestational age.

The researchers found that for all racial and ethnic groups, excessive gestational weight gain was the major contributor to LGA birth, accounting for 33.4% of LGA among whites, 36.8% among blacks, 33.3% among Hispanics, and 37.7% among Asian/Pacific Islanders.

In contrast, GDM accounted for just 2.0% of LGA among whites, 8.0% among blacks, 3.9% among Hispanics, and 4.0% among Asian/Pacific Islanders. A BMI of greater than 25 kg/m2 accounted for 15.9% of LGA among whites, 22.4% among blacks, 16.0% among Hispanics, and 9.5% among Asian/Pacific Islanders.

"Depending on race or ethnic [group], our results suggest that a reduction in LGA prevalence ranging between 46.8% and 61.0% might result if women were not overweight or obese, did not have GDM, and did not gain an excessive amount of weight," the authors write. However, they note that preventing obesity, which would also affect incidence of GDM, would require a long-term intervention, beginning among adolescents.

"In contrast to prevention of obesity and GDM, preventing excess gestational weight gain may be more feasible as it is monitored during pregnancy," the authors write.

In the womb, LGA infants increase the risk for long labor, caesarean delivery, shoulder dystocia, and birth trauma. These infants are more likely to suffer fetal hypoxia and intrauterine death. In later life, they are at higher risk for diabetes, obesity, metabolic syndrome, asthma, and cancer, the authors write.

"Prevention efforts should include all women regardless of their prepregnancy BMI because more than 30% of LGA could be prevented among women with a normal BMI," the authors write. "Furthermore, preventing excessive gestational weight gain will also aid in reducing postpartum weight retention, which in turn may contribute to the development of obesity while entering into the next pregnancy, especially for closely spaced pregnancies. Therefore, it is important for health care providers to be aware of current gestational weight gain guidelines and make efforts to implement effective strategies to prevent excess gestational weight gain."

The authors have disclosed no relevant financial relationships.

Obstet Gynecol. Published online March 4, 2014. Abstract


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