Self-reported pre-pregnancy weight versus weight measured at first prenatal visit: effects on categorization of pre-pregnancy body mass index.

To compare classification of pre-pregnancy body mass index (BMI) using self-reported pre-pregnancy weight versus weight measured at the first prenatal visit. Retrospective cohort of 307 women receiving prenatal care at the faculty and resident obstetric clinics at a Massachusetts tertiary-care center. Eligible women initiated prenatal care prior to 14 weeks gestation and delivered singleton infants between April 2007 and March 2008. On average, self-reported weight was 4 pounds lighter than measured weight at the first prenatal visit (SD 7.2 pounds; range: 19 pounds lighter to 35 pounds heavier). Using self-reported pre-pregnancy weight to calculate pre-pregnancy BMI, 4.2 % of women were underweight, 48.9 % were normal weight, 25.4 % were overweight, and 21.5 % were obese. Using weight measured at first prenatal visit, these were 3.6, 45.3, 26.4, and 24.8 %, respectively. Classification of pre-pregnancy BMI was concordant for 87 % of women (weighted kappa = 0.86; 95 % CI 0.81-0.90). Women gained an average of 32.1 pounds (SD 18.0 pounds) during pregnancy. Of the 13 % of the sample with discrepant BMI classification, 74 % gained within the same adherence category when comparing weight gain to Institute of Medicine recommendations. For the vast majority of women, self-reported pre-pregnancy weight and measured weight at first prenatal visit resulted in identical classification of pre-pregnancy BMI. In absence of measured pre-pregnancy weight, we recommend that providers calculate both values and discuss discrepancies with their pregnant patients, as significant weight loss or gain during the first trimester may indicate a need for additional oversight with potential intervention.

Efforts needed to provide Institute of Medicine-recommended guidelines for gestational weight gain.

OBJECTIVE: To estimate body mass index (BMI)-specific gestational weight gain recommendations and frequency of weight and gestational weight gain discussions and documentation. METHODS: Medical record review of 477 randomly selected patients who met inclusion criteria and who received care in faculty and resident clinics at a central Massachusetts tertiary care center. Patients started prenatal care at or before 14 weeks of gestation and delivered between April 2007 and March 2008. RESULTS: Our patients were mean (+/-standard deviation) 27.8 (+/-6.3) years, 69.8% multiparous, 45.3% white, 10.5% black, and 15.9% Hispanic. Mean gestational age at initial visit was 9.6 (+/-2.1) weeks and mean prenatal visits attended were 12.6 (+/-2.7). Using prenatal chart data alone, BMI was not calculable for 41.2% of patients due to missing height (27.7%), prepregnancy weight (27.9%), or both (14.5%). In the total sample, documentation was missing with regard to BMI (95.4%), gestational weight gain (85.3%), gestational weight gain goals (90.1%), and discussion of weight (88.9%). Supplemental data were obtained to calculate prepregnancy BMI for 469 patients. Per 1990 (BMI at least 26.1) and 2009 (BMI at least 25.0) guidelines, 42% and 49% of patients were overweight or obese, respectively, before pregnancy. Analysis of actual gestational weight gain by BMI revealed that 76% of overweight and 65% of obese patients gained excessively. CONCLUSION: Prenatal care providers should include recording height and weight to calculate BMI and to provide BMI-specific gestational weight gain guidelines. LEVEL OF EVIDENCE: III.