To compare gestational age (GA) estimates in early pregnancy, determined by last menstrual period (LMP), human chorionic gonadotropin (h CG) concentration, ultrasound crown–rump length (Hadlock formula), and ovulation day (luteinizing hormone surge plus 1 day).
After restricting the analysis to subjects with first-trimester prenatal care, a nonmissing date of the last menstrual period (LMP), and early ultrasound ( = 1,135), SGA subjects’ ultrasound GA was 5.5 days less than their LMP GA, on average.This information should not be used for the diagnosis or treatment of any health problem or disease.THIS INFORMATION IS NOT INTENDED TO REPLACE CLINICAL JUDGMENT OR GUIDE INDIVIDUAL PATIENT CARE IN ANY MANNER. Medscape's clinical reference is the most authoritative and accessible point-of-care medical reference for physicians and healthcare professionals, available online and via all major mobile devices. The clinical information represents the expertise and practical knowledge of top physicians and pharmacists from leading academic medical centers in the United States and worldwide.With adjustment for maternal age, smoking, and first-trimester vaginal bleeding, standard guidelines for adjudicating differences in ultrasound and LMP dating underestimated SGA birth by 12.9% and overestimated preterm delivery by 8.7%.This methodological approach can be applied by researchers using different study populations in similar research contexts. Schneider C, Mc Crindle BW, Carvalho JS, Hornberger LK, Mc Carthy KP, Daubeney PE. Pasquini L, Mellander M, Seale A, Matsui H, Roughton M, Ho SY, Gardiner HM. Quartermain MD, Cohen MS, Dominguez TE, Tian Z, Donaghue DD, Rychik J.