Lowering Gestational Diabetes Risk by Prenatal Weight Gain Counseling

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

Disclosures

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

In This Article

Abstract and Introduction

Abstract

Purpose: Excess weight gain during pregnancy is at epidemic proportions, and pregnancy complications are also on the rise. We sought to determine whether better weight gain counseling of expectant mothers will improve obstetric outcomes.

Methods: Our historic control study design included 2 years of preintervention data, then 6 months of physician and staff training in prenatal weight gain counseling in accordance with 2009 Institute of Medicine guidelines, and finally, 2 more years of data collection for postintervention outcomes. Seven family medicine residency clinics monitored 1571 continuity prenatal cases. Counseling recommendations were noted and the following outcomes were analyzed: gestational age, birth weight, route of delivery, and the incidences of hypertension and gestational diabetes. Multiple logistic regression was used to control for demographic variables and body mass index at enrollment.

Results: Institute of Medicine congruent counseling increased from 10% to 63% (P < .01). Excess weight gain decreased from 46.4% to 41.5% (adjusted odds ratio [AOR] = 0.85; 95% CI, 0.63–1.16; P = .10). Gestational diabetes decreased significantly from 11.5% to 7.3% (P = .008). The difference remained statistically significant even after adjusting for prepregnancy obesity and other clinical and demographic characteristics (AOR = 0.54; 95% CI, 0.32–0.91; P = .02). Differences in gestational age, birth weight, hypertension, primary cesarean, and shoulder dystocia were not statistically significant.

Conclusions: Improved weight gain counseling of prenatal patients by physicians did reduce the pregnancy complication of gestational diabetes. This occurred even though the trend toward less excess weight gain was not statistically significant.

Introduction

Weight gain and nutrition influence the health of both mothers and their offspring. The prenatal period presents an opportunity to guide women in lifestyle changes because of frequent visits, motivation to avoid delivery complications, and a strong desire to have a healthy baby.[1] Despite this opportunity, excessive weight gain in pregnancy is of epidemic concern in the United States. As of 2008, 53% of normal weight women, 72% of overweight women, and 83% of obese women gained excess weight during pregnancy.[2]

Both high prepregnancy body mass index (BMI) and excessive gestational weight gain correlate with obstetric complications. In 2009, the Institute of Medicine (IOM) reviewed the evidence available at the time in the process of updating their guidelines for recommended weight gain during pregnancy.[3] It was not clear then how much of the increased risk is due to prepregnancy weight versus further weight gain during the pregnancy. New data are rapidly becoming available to shed light on this possible distinction. This is clinically important because standard prenatal care beginning at 8 to 12 weeks of gestation can affect only gestational weight gain, but not prepregnancy BMI.

Several newer studies on prepregnancy BMI clarify the relationship with pregnancy complications. In 2015, the British Columbia Perinatal Data registry of 226,958 births reported that 10% lower prepregnancy BMI was associated with 10% lower preeclampsia, gestational diabetes, macrosomia, and stillbirth. From 20% to 30% lower BMI was required to see lower rates of cesarean, shoulder dystocia, neonatal intensive care admission, and neonatal mortality.[4] A 2015 cohort study from Beijing, China (n = 14,451) confirmed the higher prepregnancy BMI association with higher preeclampsia, gestational diabetes, cesarean, and macrosomia (even after controlling for gestational diabetes).[5]

Not enough is known about the specific effect of excess prenatal weight gain on top of already high prepregnancy BMI. We found 2 major reports suggesting that preventing excessive weight gain during pregnancy has the potential to promote better pregnancy outcomes: both looked at outcomes stratified by prepregnancy BMI to isolate the effect of subsequent prenatal weight gain. The first study was a secondary analysis of a National Institutes of Health trial of vitamin C and E to prevent preeclampsia (n = 9969) that showed excess weight gain was associated with increased hypertensive disorders, cesarean, and macrosomia.[2] The second study was a 2017 meta-analysis of 23 studies including 1.3 million mothers with excess prenatal weight gain associated with higher rates of macrosomia and cesarean delivery.[6]

Counseling is challenging because medical prenatal visits are brief and a uniform approach cannot fit all encounters. Advice must be individualized to a mother's culture, values, habitus, and personal circumstances. Decades ago, the focus was on limiting weight gain in all pregnant women. The 2009 IOM guideline provided a consensus that maternal weight gain goals vary depending on initial BMI. Maternity care providers need to know how to both encourage minimum healthy weight gain and prevent excessive weight gain, all while maintaining positive rapport with their patients.[3]

Despite the guideline and possible consequences of excessive weight on pregnancy, health care providers often do not counsel per the recommended guideline because of many perceived barriers.[1] In Ontario, Canada, only 29% of prenatal patients received a weight gain prescription from their physician (and only 12% of the patients met the prescribed weight gain goal).[7] Nurse practitioners, physicians, and midwives give varying recommendations on the weight gain range they recommend. Some advise a total weight gain amount regardless of prepregnancy BMI, whereas others advise an amount lower than the IOM recommendations. Providers have given many reasons for not adhering to the IOM guidelines, ranging from fear of patient stigmatization to perceived lack of efficacy.[1]

In 2014, when this study was designed, clinical trials to prevent excess weight gain during pregnancy had been few, usually involved diet counseling or physical activity, and showed modest results. In a 2012 meta-analysis of behavioral counseling (3 studies that could be combined, n = 443), intervention lowered excess weight gain, but the confidence interval was wide and crossed 1 (relative risk [RR] = 0.47; CI, 0.08–2.85).[8] A 2015 meta-analysis of 13 articles involving 2500 sedentary women showed that an exercise program decreased pregnancy weight gain by 1.1 kg and significantly decreased gestational diabetes (from 9.0% to 4.8%; RR = 0.69; CI, 0.52–0.9).[9] But, that meta-analysis excluded a high-quality randomized trial of exercise for 375 expectant mothers that failed to show a significant decrease in gestational diabests (7% in the intervention group vs 6% for control, P = .52).[10]

The Family Medicine Midwest Maternity Care Collaborative was assembled to heed the IOM 2009 call to action, and we designed this study. Our hypothesis was that provider and staff education will increase the proportion of prenatal patients being counseled according to the 2009 IOM updated weight gain in pregnancy guideline and will lower excess weight gain. Our secondary goals were to measure the effects, if any, on pregnancy outcomes.

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