Dietary assessment

The dietary intake of Cincinnati participants was assessed via 3 random 24-h dietary recall interviews conducted in person or by phone between weeks 4 and 13 postpartum. Trained interviewers from the Bionutrition Core of the Clinical Translational Research Center at Cincinnati Children’s Hospital Medical Center used the USDA multiple-pass method to ensure accurate collection of data with regard to food items and amounts consumed. Participants were also provided with instructions and handouts to assist them with estimating portion sizes during the interview.

Nutrition Data Systems for Research (NDSR; Nutrition Coordinating Center, University of Minnesota) was used to assess total energy and macronutrient consumption, as well as intakes from food groups, including meat and dairy groups and subgroups. Results from the 3 d of intake were averaged to obtain an estimation of usual daily intake. The NDSR software and foods database provide the highest quality analysis of nutrients for research purposes, with a complete profile of >150 nutrients and other food components for every item in the database. To reflect the marketplace throughout the study, dietary intake data were collected by using NDSR software versions 2006, 2007, and 2008; and final calculations were completed by using NDSR 2009. The NDSR time-related database updates analytic data while maintaining nutrient profiles true to the version used for data collection (20).