title: Unlike pregnant adult women, pregnant adolescent girls cannot maintain glycine flux during late pregnancy because of decreased synthesis from serine.
abstract: During pregnancy, glycine and serine become more important because they are the primary suppliers of methyl groups for the synthesis of fetal DNA, and more glycine is required for fetal collagen synthesis as pregnancy progresses. In an earlier study, we reported that glycine flux decreased by 39% from the first to the third trimester in pregnant adolescent girls. As serine is a primary precursor for glycine synthesis, the objective of this study was to measure and compare glycine and serine fluxes and inter-conversions in pregnant adolescent girls and adult women in the first and third trimesters. Measurements were made after an overnight fast by continuous intravenous infusions of 2H2-glycine and 15N-serine in eleven adolescent girls (17·4 (se 0·1) years of age) and in ten adult women (25·8 (se 0·5) years of age) for 4 h. Adolescent girls had significantly slower glycine flux and they made less glycine from serine in the third (P<0·05) than in the first trimester. Baby birth length was significantly shorter of adolescent girls (P=0·04) and was significantly associated with third trimester glycine flux. These findings suggest that the pregnant adolescent cannot maintain glycine flux in late pregnancy compared with early pregnancy because of decreased synthesis from serine. It is possible that the inability to maintain glycine synthesis makes her fetus vulnerable to impaired cartilage synthesis, and thus linear growth.
authors.affiliation: 1US Department of Agriculture/Agricultural Research Service,Department of Paediatrics,Children's Nutrition Research Center,Baylor College of Medicine,Houston,TX 77030,USA.
authors.forename: Jean W
authors.initials: JW
authors.lastname: Hsu
authors.affiliation: 2Department of Child and Adolescent Health,University of the West Indies,Mona,Kingston-7,Jamaica.
authors.forename: Minerva M
authors.initials: MM
authors.lastname: Thame
authors.affiliation: 3Department of Obstetrics and Gynaecology,University of the West Indies,Mona,Kingston-7,Jamaica.
authors.forename: Raquel
authors.initials: R
authors.lastname: Gibson
authors.affiliation: 2Department of Child and Adolescent Health,University of the West Indies,Mona,Kingston-7,Jamaica.
authors.forename: Tameka M
authors.initials: TM
authors.lastname: Baker
authors.affiliation: 1US Department of Agriculture/Agricultural Research Service,Department of Paediatrics,Children's Nutrition Research Center,Baylor College of Medicine,Houston,TX 77030,USA.
authors.forename: Grace J
authors.initials: GJ
authors.lastname: Tang
authors.affiliation: 1US Department of Agriculture/Agricultural Research Service,Department of Paediatrics,Children's Nutrition Research Center,Baylor College of Medicine,Houston,TX 77030,USA.
authors.forename: Shaji K
authors.initials: SK
authors.lastname: Chacko
authors.affiliation: 4National Institute for Health Research (NIHR) Southampton Biomedical Research Centre,Southampton General Hospital (MP 113),Tremona Road,Southampton SO16 6YD,UK.
authors.forename: Alan A
authors.initials: AA
authors.lastname: Jackson
authors.affiliation: 1US Department of Agriculture/Agricultural Research Service,Department of Paediatrics,Children's Nutrition Research Center,Baylor College of Medicine,Houston,TX 77030,USA.
authors.forename: Farook
authors.initials: F
authors.lastname: Jahoor
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D005998:Glycine / Q000378:metabolism*; D006801:Humans; D039382:Maternal Nutritional Physiological Phenomena; D008954:Models, Biological; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000502:physiology; D011263:Pregnancy Trimester, Third / Q000502:physiology; D012694:Serine / Q000378:metabolism*
chemical_list: D012694:Serine; D005998:Glycine
keywords: Glycine; Pregnant adolescent girls; Pregnant adult women; Serine