Lowering Gestational Diabetes Risk by Prenatal Weight Gain Counseling

Evelyn M. Figueroa, MD; Kara Nitti, MPH; Stephen M. Sladek, MD


J Am Board Fam Med. 2020;33(2):189-197. 

In This Article


By improving weight gain counseling in accordance with the IOM 2009 guideline, we were successful in documenting a decrease in the incidence of gestational diabetes (number needed to treat = 24_. There were no significant decreases in macrosomia, postdate pregnancy, primary cesarean delivery, hypertensive disorders, and shoulder dystocia.

Our data confirmed the known associations[2,5] between increased prepregnancy BMI and increased hypertensive disorders, gestational diabetes, birth weight of >4 kg, and primary cesarean (data not shown). Our influence on the incidence of gestational diabetes agrees with recent evidence: in a 2017 meta-analysis, dietary advice showed some effectiveness in reducing gestational diabetes (RR = 0.60; 95% CI, 0.35–1.04; 5 trials; n = 1279; P = .07).[14] In addition, in agreement with our results, others did not show clear decreases in fetal macrosomia, cesarean section, nor preeclampsia.[15] We speculate that this is due to the powerful effect of prepregnancy BMI on these outcomes. Our intervention did not target changing prepregnancy BMI.

Despite the increased BMI among the mothers who presented for care in 2015–2017, we were still able to show a decrease in the incidence of gestational diabetes with improved weight gain counseling. We hypothesize this is due to more mothers modifying their eating and activity before gestational diabetes screening at 24 weeks of gestation and, hence, more passing the screen as "normal." Clinicians and policymakers can be more confident that time spent in prenatal counseling will be beneficial. The IOM Pregnancy Weight Gain Guideline has been validated by this study and others.[14,16] Hopefully our decrease in gestational diabetes will translate into less type 2 diabetes and fewer complications later in the lives of our mothers.

Additional research is needed to discover and validate effective prenatal clinical interventions to mitigate the strong influence of prepregnancy BMI on obstetric outcomes. Weight gain counseling before pregnancy at family planning, primary care, and postpartum medical visits might be fruitful episodes of care for new interventions.

Strengths and Limitations

Strengths of this study include its real world, clinical approach, its roots in motivational interviewing, and the brevity of this type of educational intervention.

Limitations of our study include the pre/postintervention design, rather than a contemporaneous randomized trial. However, by the time of our intervention (2014) it would have been unethical to randomize care sites to neglect the IOM expert opinion clinical guideline that was published in 2009. Our major finding of reduced gestational diabetes could be due to some factor that changed between preintervention (2012–13) and postintervention (2015–17) time periods other than our educational intervention to improve weight gain counseling. Our multiple regression analysis indicated this was not likely: there was no significant association between demographic variables at entry to prenatal care and pregnancy outcomes in pre- versus postintervention groups. A per protocol analysis was also confirmatory.

A second limitation was that the type, intensity, timing, and recording of prenatal weight gain counseling were variable across individual sites and providers. To investigate timing, in the postintervention period, we added data collection (at 6 of 7 sites) of whether weight gain counseling began before 20 weeks of gestation. That was the case in 89.7% of postintervention mothers. This was to ensure enough time was available for the counseling to have an influence. If few of the mothers had been counseled before 20 weeks, it would have been harder to argue that the counseling itself made any difference in the outcomes. The documentation of weight gain counseling may also have been influenced by the availability of electronic medical record templates or prompts at some sites but not at others. There is the possibility that weight gain counseling was performed for some patients but not clearly documented in their prenatal record and was, hence, misclassified as "not done" in our data reporting.