Prediction of Infant Birth Weight by GDM Screening Tests: Importance of plasma triglyceride
- Robert H Knopp, MD,
- M Scott Magee, MD,
- Carolyn E Walden, MS,
- Bartolome Bonet, MD, PHD and
- Thomas J Benedetti, MD
- Departments of Medicine and Obstetrics and Gynecology, School of Medicine, and the Northwest Lipid Research Clinic, University of Washington Seattle, Washington
- Address Correspondence and reprint requests to Robert H. Knopp, MD, Northwest Lipid Research Clinic, Room 465, 326 Ninth Avenue, Seattle, Wa 98104.
Abstract
OBJECTIVE We measured plasma glucose, GHb, GPro, IRI and TG at 24–28-wk gestation to determine the extent of elevations in GDM and relationships to glucose intolerance and infant macrosomia.
RESEARCH DESIGN AND METHODS Plasma samples were obtained 1 h after ingestion of 50 g glucose after an overnight fast in 521 randomly selected negative screenees, 264 positive screenees with GTT−, and 96 positive screenees with GTT+ (GDM).
RESULTS Screening test values in GDM subjects exceeded the GTT− group, whose values exceeded those of negative screenees: glucose, 9.6*, 8.7*, 6.3 mM; GHb, 5.2*, 4.9*, 4.7%; GPro, 3.1*, 3.0*, 2.8%; IRI, 791*, 662*, 410 pM; and TG, 2.3*, 1.9, 1.9 mM, (*P < 0.005 vs. negative screenees). TG was the only test elevated in the GDM but not in the GTT− groups. Screening test values correlated with GTT values in the following order (strongest to weakest): glucose* > TG* > GHb* > IRI > GPro (*statistical significance). Plasma TG was the only screening test significantly associated with birth weight corrected for gestational age (birth-weight ratio) (r = 0.09–0.16) (P < 0.05 to < 0.01) and was of the same order as 1- and 2-h GTT associations with birth weight (r = 0.13 and 0.14, respectively) (P < 0.05 to < 0.01). Plots of TG/birth-weight ratio increased linearly to the 80–90th TG percentile in negative screenees and GTT− subjects. GDM subjects followed this trend but with more variation. Above the 90th percentile for TGs, birth-weight ratio trended lower, significantly so when the groups were combined (P < 0.05). In multivariate analysis, TG was associated with birth-weight ratio even when maternal prepregnancy weight and pregnancy weight gain associations with TG and birth-weight ratio were controlled (P < 0.019).
CONCLUSIONS Of the five screening tests evaluated, all were elevated in GDM, but TG is the best discriminator of GDM from the GTT− group, and it is the only test significantly related to birth-weight ratio—and to glucose intolerance besides glucose itself. The TG association with birth weight is not explained fully by maternal weight. The results suggest that plasma TG may be a physiological contributor to infant birth weight. Further evaluation of plasma TG in GDM screening is justified, but GHb, GPro, and IRI appear to hold less promise.
- Received November 6, 1991.
- Revision received May 21, 1992.
- Accepted May 21, 1992.
- Copyright © 1992 by the American Diabetes Association
