Association of Gestational Weight Gain With Maternal and Infant Outcomes: A Systematic Review and Meta-analysis

Abstract

Importance: Body mass index (BMI) and gestational weight gain are increasing globally. In 2009, the Institute of Medicine (IOM) provided specific recommendations regarding the ideal gestational weight gain. However, the association between gestational weight gain consistent with theIOM guidelines and pregnancy outcomes is unclear.

Objective: To perform a systematic review, meta-analysis, and metaregression to evaluate associations between gestational weight gain above or below the IOM guidelines (gain of 12.5-18 kg for underweight women [BMI <18.5]; 11.5-16 kg for normal-weight women [BMI 18.5-24.9]; 7-11 kg for overweight women [BMI 25-29.9]; and 5-9 kg for obese women [BMI ≥30]) and maternal and infant outcomes.

Data sources and study selection: Search of EMBASE, Evidence-Based Medicine Reviews, MEDLINE, and MEDLINE In-Process between January 1, 1999, and February 7, 2017, for observational studies stratified by prepregnancy BMI category and total gestational weight gain.

Data extraction and synthesis: Data were extracted by 2 independent reviewers. Odds ratios (ORs) and absolute risk differences (ARDs) per live birth were calculated using a random-effects model based on a subset of studies with available data.

Main outcomes and measures: Primary outcomes were small for gestational age (SGA), preterm birth, and large for gestational age (LGA). Secondary outcomes were macrosomia, cesarean delivery, and gestational diabetes mellitus.

Results: Of 5354 identified studies, 23 (n = 1 309 136 women) met inclusion criteria. Gestational weight gain was below or above guidelines in 23% and 47% of pregnancies, respectively. Gestational weight gain below the recommendations was associated with higher risk of SGA (OR, 1.53 [95% CI, 1.44-1.64]; ARD, 5% [95% CI, 4%-6%]) and preterm birth (OR, 1.70 [1.32-2.20]; ARD, 5% [3%-8%]) and lower risk of LGA (OR, 0.59 [0.55-0.64]; ARD, -2% [-10% to -6%]) and macrosomia (OR, 0.60 [0.52-0.68]; ARD, -2% [-3% to -1%]); cesarean delivery showed no significant difference (OR, 0.98 [0.96-1.02]; ARD, 0% [-2% to 1%]). Gestational weight gain above the recommendations was associated with lower risk of SGA (OR, 0.66 [0.63-0.69]; ARD, -3%; [-4% to -2%]) and preterm birth (OR, 0.77 [0.69-0.86]; ARD, -2% [-2% to -1%]) and higher risk of LGA (OR, 1.85 [1.76-1.95]; ARD, 4% [2%-5%]), macrosomia (OR, 1.95 [1.79-2.11]; ARD, 6% [4%-9%]), and cesarean delivery (OR, 1.30 [1.25-1.35]; ARD, 4% [3%-6%]). Gestational diabetes mellitus could not be evaluated because of the nature of available data.

Conclusions and relevance: In this systematic review and meta-analysis of more than 1 million pregnant women, 47% had gestational weight gain greater than IOM recommendations and 23% had gestational weight gain less than IOM recommendations. Gestational weight gain greater than or less than guideline recommendations, compared with weight gain within recommended levels, was associated with higher risk of adverse maternal and infant outcomes.

Figure 1.. Flow Diagram of Study Selection Process

^aExact breakdown for exclusion not documented. ^bThe Institute of Medicine 1990 guidelines differ from the 2009 guidelines. In the 1990 guidelines, the recommended weight gain range was 12.5 to 18 kg for women with a body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) less than 19.8; 11.5 to 16 kg for women with a BMI of 19.8 to 26.0; 7 to 11.5 kg for women with a BMI between 26.0 and 29.0; and at least 6.8 kg for women with a BMI higher than 29.0.

Figure 2.. Summary of Pooled Odds Ratios (ORs) for the Association Between Gestational Weight Gain Below and Above Guidelines With Adverse Outcomes

Pooled ORs are shown for the association between gestational weight gain below (A) and above (B) guidelines with adverse outcomes. Reference group is women with recommended weight gain in each category of body mass index (BMI; calculated as weight in kilograms divided by height in meters squared). For each outcome, the sample size represents the total number of women in the studies that assessed the outcome. For each BMI category, the sample size represents the total number of women with gestational weight gain below or above the guidelines. LGA indicates large for gestational age; SGA, small for gestational age.

Figure 3.. Obese Subgroup Analysis With Summary of Pooled Odds Ratios (ORs) for the Association Between Gestational Weight Loss, Gain Below Guidelines, and Gain Above Guidelines With Adverse Outcomes

Pooled ORs are shown for the association between gestational weight loss (A), gestational weight gain below guidelines (B), and gestational weight gain above guidelines (C) with adverse outcomes. Obesity classes indicate body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) as follows: class 1, BMI of 30 to 34.9; class 2, BMI of 35 to 39.9; and class 3, BMI of 40 or higher. Reference group is women with recommended weight gain in each category of BMI. For each outcome, the sample size represents the total number of women in the studies that assessed the outcome. For each obesity category, the sample size represents the total number of women with weight loss, gestational weight gain below the guidelines, or gestational weight gain above the guidelines.