Assessing the Accuracy of Pregnant Women in Recalling Pre-pregnancy Weight and Gestational Weight Gain

Objective: Maternity care providers can use pre-pregnancy weight (PPW) and gestational weight gain (GWG) as markers for difficult delivery, and frequently obtain this information directly from the patient. The goal of this study was to determine whether women report their PPW and GWG correctly at the end of pregnancy.

Methods: We performed a prospective cohort study of 189 women delivering between June 1, 2011, and July 31, 2011, at the Saint John Regional Hospital or the Moncton Hospital in New Brunswick. Self- reported PPW and GWG were compared with measured weights obtained from the antenatal chart and upon presentation for delivery. Patient characteristics, BMI classification, and accuracy and degree of error in recall were assessed.

Results: The majority of respondents were under 30 years of age (63.4%) and were delivering at term (96.3%). Ninety women (47.6%) were having their first baby. A record of weight measured in the first trimester was available for 98 respondents (51.9%); using this information, 44 women (44.9%) were determined to be overweight or obese at delivery. Approximately one third of women with a normal BMI were not able to recall their PPW or GWG accurately (± 1 kg). Among all BMI classes, there was a consistent pattern of under-reporting of PPW (by a mean of 1.52 kg) and over-reporting of GWG (by a mean of 1.61 kg), but several extreme outliers were identified.

Conclusion: At the time of delivery, under-reporting of PPW and over-reporting of GWG are common and difficult to predict. Maternity care providers should be aware of this discrepant reporting of PPW and GWG and recognize the implications for intrapartum management and postpartum weight loss.