AT ACOG 2017
SAN DIEGO (FRONTLINE MEDICAL NEWS) – Among obese women, weight loss, stable weight, or weight gain below Institute of Medicine guidelines may result in more favorable or similar perinatal outcomes, compared with weight gain within IOM guidelines, but not for small for gestational age, results from a retrospective cohort study showed.
“This study adds to the limited body of evidence regarding associations of low weight gain and perinatal outcomes among obese women,” Emilia G. Wilkins, MD, the lead study author, said in an interview prior to the annual clinical and scientific meeting of the American College of Obstetricians and Gynecologists. “This is the first study that uses data collected after the 2009 IOM guidelines were published. Although there have been some studies published after that time, they used older cohorts. We have a large, diverse cohort and had access to robust electronic health records, which allowed for inclusion of multiple relevant covariates.”
In an effort to contribute data to support more specific IOM guidelines for obesity classes I-III, Dr. Wilkins and her associates conducted a retrospective cohort study of 19,810 obese women who delivered singleton, live births greater than 35 weeks at Kaiser Permanente Northern California hospitals between 2009 and 2012. The researchers divided weight gain into three categories below the IOM guidelines of 5 kg-9 kg in an attempt to determine an optimal “low” weight gain category: below –2 kg, –2 kg-2 kg, and 2 kg-5 kg. They used logistic regression to estimate the odds ratios of newborn (size for gestational age, neonatal intensive care unit [NICU] admission, length of hospital stay) and maternal (mode of delivery, preeclampsia, gestational hypertension) outcomes associated with gestational weight gain below IOM guidelines.
Dr. Wilkins, a fourth-year ob.gyn. resident at Kaiser Permanente in Oakland, Calif., reported that 59% of obese women gained weight above the IOM guidelines and that gestational weight gain above the IOM guidelines was consistently associated with worse perinatal outcomes.
Among class III obese women (BMI of 40 or greater), gestational weight gain below –2 kg, compared with gestational weight gain within IOM guidelines, was associated with lower odds of large-for-gestational-age infants (OR, 0.4; 95% CI, 0.3–0.7), preeclampsia/eclampsia (OR, 0.5; 95% CI, 0.3–0.9), cesarean section (OR, 0.5; 95% CI, 0.4–0.7), NICU admission (OR, 0.7; 95% CI, 0.5–1.1), and length of stay greater than 3 days (OR, 0.5; 95% CI, 0.4–0.8), but higher odds of small for gestational age (OR, 2.61; 95% CI, 1.11–6.20). Findings were similar for other obesity classes.
“It is surprising that the protective associations for weight loss were so strong,” Dr. Wilkins said. “At least 50% lower odds of adverse outcomes [were seen], including large for gestational age, cesarean delivery, preeclampsia/eclampsia, and extended neonatal hospital stay – all of which are clinically significant and could have a major implications for maternal and child health. The degree of increased odds (2- to 2.7-fold higher) of small for gestational age was also a surprising finding and indicates the need to further assess whether the health of the small-for-gestational-age babies differed across the gestational weight gain categories.”
One surprise was that, although the weight loss group had higher odds of delivering a small for gestational age infant, there was no association with increased NICU admission or increased neonatal hospital stay,” Dr. Wilkins added.
She acknowledged certain limitations of the study, including the fact that approximately 10% of the prepregnancy weights were self-measured. Additionally, there was low statistical power to evaluate NICU and length of stay data, and maternal conditions associated with prior weight loss such as bariatric surgery were not evaluated.
Dr. Wilkins reported having no financial disclosures.