A retrospective study of gestational weight gain in relation to the Institute of Medicine’s recommendations by maternal body mass index in rural Pennsylvania from 2006 to 2015

Abstract

BackgroundIn 2009, the Institute of Medicine (IOM) published guidance on gestational weight gain (GWG) modified by maternal pre-pregnancy body mass index (BMI). Estimates indicate that less than half of US pregnant women have GWG within recommendations. This study examined GWG from before (2006–2009) and after (2010–2015) the release of the IOM guidance in a rural, non-Hispanic white population to assess the proportion of women with GWG outside of IOM guidance, whether GWG became more likely to be within IOM guidance after 2010, and identify potential maternal factors associated with GWG outside of recommendations.MethodsWe examined GWG in 18,217 term singleton births between 2006 and 2015 in which maternal pre-pregnancy BMI could be calculated from electronic medical records at Geisinger, PA, and a subset of 12,912 births in which weekly GWG in the third trimester could be calculated. The primary outcome was whether GWG was below, within, or above recommendations based on maternal BMI. The relationships between GWG, maternal BMI, parity, age at conception, gestation length, and maternal blood pressure were examined.ResultsGWG declined with increasing maternal BMI, however, more than 50% of overweight and obese women gained above IOM recommendations. About one of five women gained below recommendations (21.3%) with underweight women the most likely to gain below recommendations (33.0%). The proportion of births with usable data increased after 2010, driven by a higher probability of recording maternal weight. However, the proportion of women who gained below, within or above recommendations did not change over the ten years. GWG above recommendations was associated with higher maternal BMI, lower parity, and longer gestation. GWG below recommendations was associated with lower maternal BMI, higher parity, shorter gestation, and younger age at conception. Maternal blood pressure was higher for GWG outside recommendations.ConclusionsDespite the publication of IOM recommendations in 2009 and an apparent increase in tracking maternal weight after 2010, GWG in this population did not change between 2006 and 2015. A majority of overweight and obese women gained above recommendations. GWG below recommendations continues to occur, and is prevalent among underweight women.

Risks of preterm birth among non‐Hispanic black and non‐Hispanic white women: Effect modification by maternal age

“…All medical/obstetrical variables were categorical and included prenatal care (none, first, second or third trimester), pre‐pregnancy body mass index (BMI; underweight, normal weight, overweight, obese), rate of net gestational weight gain (inadequate, appropriate, excessive), diabetes (none, pre‐pregnancy, gestational), hypertensive disorders (none, chronic/pre‐pregnancy, or pregnancy‐associated), and asthma (yes/no). As previous studies have documented under‐reporting of maternal medical conditions on the birth certificate, ICD‐9 codes abstracted from the hospital billing records were used in conjunction with birth certificate data to define the hypertension, diabetes and asthma variables.…”

Factors associated with gestational weight gain: a cross-sectional survey

“…In 48% of cases, the increase in weight was higher, and in 21% of the cases, weight gain was lower than that recommended by the US Institute of Medicine (IOM) [ 1 , 2 ]. A survey conducted between 2006 and 2015 on over 18,000 women in rural Pennsylvania showed that only 25.3% of women in this population gained weight within the recommended range – 21.3% gained an amount below and 52.9% gained an amount above the range in the IOM guidelines [ 3 ]. In a group of over 14,000 Italian women, the recommended GWG was found in 40.8%, in 30.1% of the women, GWG was lower, and in 29.1%, it was higher than the guidelines [ 4 ].…”

Minimization of bias in measures of gestational weight gain

“…Another source of bias in calculating GWG is the timing of the final weight measurement prior to delivery. 16,17 Ideally, the final weight should be measured as close to the delivery date as possible, and an adjustment made to account for gestational age when the final weight is not measured close to the delivery date.…”

“…For example, differences in timing of the last measured weight and delivery have been noted among women with term and preterm deliveries and among women with stillbirths. 19,21 Cut-offs of within 7 days of delivery have been applied in some studies 17 and databases, including the British Columbia Perinatal Data Registry. 19,22 However, evidence-based cutoffs for delivery weight are not established.…”