Percentile distribution for anthropometric variables used to estimate body composition in pregnant women

Anthropometric indicators of body composition, reflective of fat and lean compartments in pregnant women, undergo changes throughout gestation. The adequate interpretation of these indicators requires the availability of percentile distribution values for each week of gestational age. The objective was to determine the percentile distribution for subcutaneous skin-fold thicknesses: biceps, triceps, subscapular, mid-thigh, and both arm fat and arm muscle areas for each week of gestational age. This descriptive and cross-sectional study included 4,481 measurements of anthropometric variables obtained from 745 pregnancies out of 719 subjects aged between 19 and 39 years, well-nourished, healthy, without clinical edema, single pregnancy, and validated gestational age. Evaluations were conducted at the Centro de Atencion Nutricional Infantil Antimano, between 1998 and 2012. The anthropometric measurements were performed by standardized anthropometrists. Descriptive statistics, bivariant correlations, and percentiles 3, 10, 25, 50, 75, 90, and 97 were calculated for each week of pregnancy between weeks 8 thru 37. The number of measurements performed for each variable studied at each week of gestation ranged between 100 and 236. The behavior of the variables reflecting the fat component showed increases as the gestational age advanced (1.86 cm2), whereas the muscle area showed decreases (-0.02 cm2). The most noticeable variations were seen in the subscapular and mid-thigh skin-fold thicknesses 2.90 mm and 5.0 mm, respectively. The availability of percentile distributions of the anthropometric variables used in the evaluation of body composition for pregnant women per gestational age, contributes to optimizing the nutritional categorization in this population group.