Predictors of inadequate gestational weight gain according to iom recommendations and intergrowth-21st standards: the araraquara cohort study.

Background: Gestational weight gain (GWG) is a critical factor for maternal and fetal health.

Objective: To identify maternal predictors of inadequate GWG according to the 2009 Institute of Medicine (IOM) recommendations and Intergrowth-21st standards.

Methods: A prospective epidemiological cohort study conducted from 2017 to 2023 in southeastern Brazil assessed 1,557 women at three different stages of pregnancy (≤ 18, 20-26, and 30-36 weeks of gestation) and at delivery. Sociodemographic, obstetric, lifestyle, nutritional, and maternal morbidity characteristics were collected, along with biochemical parameters.

Results: Among the participants, 38.7% had GWG above IOM recommendations, while 67.5% had GWG above the Intergrowth-21st standards. Multinomial logistic regression analysis showed that women with pre-pregnancy obesity and women with the highest body fat percentage had, respectively, a 95% (OR = 1.95; 95% CI: 1.08-3.51) and 1% (OR = 1.01; 95% CI: 1.01-1.05) higher chance of GWG above IOM recommendations. Pregnant women in the lowest tertile of height, smokers, number of previous pregnancies, and women living in crowded homes had, respectively, a 57% (OR = 0.57; 95% CI: 0.41-0.80), 36% (OR = 0.64; 95% CI: 0.37-0.86), 35% (OR = 0.65; 95% CI: 0.43-0.97), and 14% (OR = 0.86; 95% CI: 0.59-0.86) lower chance of GWG above IOM recommendations. Women with diabetes were 2.53 times more likely (OR = 2.53; 95% CI: 1.32-4.83) to have GWG below IOM recommendations. Using the Intergrowth-21st standards, women with the highest body fat percentage had a 12% (OR = 1.12; 95% CI: 1.02-1.24) higher chance of GWG above the 90th percentile. Pregnant women in the lowest tertile of height were 2.82 times more likely (OR = 2.82; 95% CI: 1.08-8.13) and women with the lowest hemoglobin concentrations had a 41% lower chance (OR = 0.59; 95% CI: 0.39-0.88) of having GWG below the 10th percentile. While both guidelines identified body fat percentage and pre-pregnancy obesity as significant predictors of excessive GWG, the Intergrowth-21st standards captured a higher percentage of women exceeding GWG limits.

Conclusion: The findings underscore the importance of comparing two instruments for assessing the adequacy of GWG. The IOM and Intergrowth-21st standards provide complementary insights, which can help implement targeted interventions for specific groups of women based on their nutritional and socioeconomic status, lifestyle, and obstetric factors to prevent pregnancy-related complications.