Research Seminar

MWRI WIP: Defining Normal and Abnormal Fetal Growth: Individualized and Customized References Versus Standards

May 20, 2014
12:00 PM - 1:00 PM
Katherine Laughon Grantz, MD, MS
Investigator, Epidemiology Branch, Division of Intramural Population Health Research, NICHD, NIH
Magee-Womens Research Institute Conf Center, 204 Craft Ave
Physicians earn 1.0 CME credits
Light lunch provided and registration is not required.

Characterizing trajectories of normal and abnormal fetal growth is important for monitoring pregnancy and determining appropriate interventions which will improve the chances of healthy pregnancy outcomes. However, defining normal and abnormal fetal growth in clinical practice and research has not been straightforward. Most clinical and epidemiologic studies have classified abnormal growth based on birth weight outcome, as small-for-gestational-age (SGA) or large-for-gestational-age (LGA) using cross-sectional birth weight references that inadequately reflect patterns of under- or overgrowth and normative or optimal growth in fetuses at preterm gestations. Individualized references for prediction are promising, but given limitations and complexity, have not been adopted into routine clinical practice. Customized references are based on the premise that birth weight varies by maternal and fetal physiologic factors (e.g. race/ethnicity, parity, sex), but make several assumptions and may be limited to detect meaningful differences when using stillbirth or neonatal death as the outcome. Defining abnormal fetal growth remains a pressing clinical challenge. Further, until recently there have been few studies that have established fetal growth charts and/or velocity in diverse populations. This presentation will review my ongoing work in these areas, as well as research identifying demographic and clinical risk factors for SGA recurrence and how these risk factors differ from women whose first pregnancy was non-SGA. I will also introduce the NICHD Fetal Growth Study, a cohort project conducted at 12 U.S. sites that recently finished accruing subjects. The study was designed specifically: 1) to establish an ultrasound standard for normal singleton fetal growth (velocity) and size for gestational age in the U.S. population; 2) to improve estimation of abnormal fetal growth; and 3) to examine a number of factors, including nutrition, psychosocial characteristics, and gravid conditions, for their effect on fetal growth.