718: First trimester maternal weight in USA continues to rise

Abstract

Mark Evans, Terrence Hallahan, Hsiao-Pin Liu, Jon Carmichael, David Krantz Comprehensive Genetics, Genetics, New York, NY, Perkin Elmer, NTD Labs, Melville, NY OBJECTIVE: To determine whether the average weight of pregnant women continues to increase between 2003 and 2011. STUDY DESIGN: First trimester maternal weight (MW) data (lb) were evaluated on 1,677,116 patients, collected as part of first trimester aneuploidy screening conducted between 2003 and 2011. The study population was 65% Caucasian, 12% Hispanic, 10% African American, 7% Asian, 3% Asian Indian and 3% other ethnic Groups. If a patient had more than one test during this time period data from one of their tests was selected at random. Geometric mean maternal weight values were adjusted for age, gestational age at time of test and ethnicity by determining the least-squares means based on ANOVA using log-transformed weight values. The adjusted geometric mean maternal weight values were then regressed against time (with standard error of the coefficients adjusted for autocorrelation and number of patients during each time period). RESULTS: Overall over the study time period, the average weight of the total population increased by 4.0% while the increase in the top 10% group was 7.3%. A majority of the increase occurred from 2003 to 2007 (3.0% and 4.7% for the total population and top 10%, respectively). Regression analysis determined that the increase was not linear but rather followed a polynomial quadratic pattern for both the overall population as well as the top 10% (P value of the quadratic term 0.001 for both overall and top 10% of the population). CONCLUSION: The continuous increase in the mean MW particularly the top 10% is of significant concern because of increased rate of pregnancy complications, more difficult ultrasound examinations, reduced fetal fraction of DNA leading to poorer performance of NIPT testing and the need to ensure that weight adjustment formulas used for aneuploidy screening are still applicable. The slowing of the trend in the increase in MW needs to be studied but is a positive sign for public health.