Effects of Gestational Weight Gain on Delivery Outcomes in an Obese, Low-Income Population

Allison Archer Sellner, MD; Abigail Hook Garbarino, MD, DiMiao, PhD; Lisa Marie Hollier, MD, MPH; Bani Maheshwari Ratan, MD


South Med J. 2021;114(11):686-691. 

In This Article


The obesity epidemic is a growing problem that will continue to affect the health and well-being of patients if inadequately addressed. Pregnancy is an entry point into care in which patients are highly motivated and can be counseled on appropriate lifestyle changes that can affect their health beyond the prenatal period.[22,23] Most obese women who gain excess weight during pregnancy never manage to completely lose the weight following delivery, resulting in postpartum weight retention that increases the likelihood of long-term obesity and medical comorbidities.[7,24,25] These sequelae must be weighed against the risks of SGA and preterm birth when assessing for appropriate gestational weight gain or loss in obese pregnant women.

Studies have shown mixed results regarding SGA with weight gain below the National Academy of Medicine guidelines in the obese population. Initial studies demonstrated a higher risk of SGA in obese women with lower gestational weight gain or weight loss, but these studies did not stratify for the class of obesity.[19,26] Recent meta-analyses with BMI stratification have showed an increased risk of SGA with gestational weight loss or gain below the guidelines for all classes of obesity;[14,27] however, these studies do not account for the differing socioeconomic and racial backgrounds of patients. In our study, the total population had a statistically significant increase in SGA with women who lost weight during pregnancy. This composite result was caused by class 1 patients with weight loss having a significant increase in SGA, with no significant difference seen in class 2 or class 3 patients with weight loss. Similarly, across classes, there was no statistically significant increase in SGA with weight gain below guidelines.

Previous studies also have shown an increased risk of preterm delivery with weight gain below National Academy of Medicine recommendations or weight loss, but they have either not differentiated between spontaneous preterm labor and induced preterm delivery or stratified the patients and outcomes by class of obesity.[14,28] This study examined both preterm labor and induced preterm delivery while adjusting weight gain for GA and examining outcomes by obesity class. Both outcomes were significantly increased in class 1 and class 2 obesity patients with weight loss. This relation did not persist for class 3 obese patients with weight loss or across all obesity classes when weight gain was below guidelines. Previous studies have shown that as maternal BMI increases, the association between gestational weight gain below guidelines and preterm delivery diminishes.[29,30] Our research adds to the knowledge base by showing that the same relation also may exist for spontaneous preterm labor.

The reasons behind obese patients having weight loss or weight gain below guidelines also has not previously been explored. In our study, class 3 patients who lost weight were significantly more likely to receive a diagnosis of gestational diabetes mellitus. This may have increased attention to dietary control, thus resulting in weight loss. The lack of SGA in our study for those class 3 patients who had weight loss may be the result of tighter glycemic control in the setting of gestational diabetes mellitus. Given the lack of SGA, preterm labor, or preterm delivery in class 3 patients with weight gain below the guidelines and weight loss, this group may benefit in the long term from gaining less weight that the current National Academy of Medicine guidelines indicate.

A strength of the study is that because of the relatively small cohort, we were able to thoroughly review charts for exact outcomes. This allowed a detailed analysis of indication for preterm birth, reason for cesarean section, and review of other medical conditions. This study population also was predominantly a low-income, racial minority population. The repercussions of weight loss in obese gravida may vary based on race and socioeconomic classes, so studying these topics in diverse patient populations is important.

The limitations of our study include its retrospective, nonrandomized nature as well as its small sample size, with only 890 patients fulfilling the requirements of the study. In addition, our study does not include the long-term effects of limited weight gain on the infants of obese women. Future studies following these infants into childhood and assessing for cognitive, behavioral, and developmental progression would need to be performed to assess for any unforeseen outcomes of changing the weight gain guidelines during pregnancy. Finally, a larger cohort would have been more adequately powered to study all of the effects. Examining these factors in a population of >5000 subjects would be more likely to decrease a type II error.