title: Maternal plasma homocysteine concentrations are not increased in twin pregnancies.
abstract: OBJECTIVE
  We tested the hypothesis that twin pregnancies would lead to increased maternal plasma homocysteine. We further hypothesized that twin pregnancies complicated by preeclampsia would have increased plasma homocysteine compared to twin pregnancies without preeclampsia and normal singleton pregnancies.
  
  
  METHODS
  Plasma was collected at delivery from 127 nulliparous subjects: 57 women with normal singleton pregnancies, 39 women with singleton and preeclampsia, 17 women with uncomplicated twin pregnancies, and 14 women with twins and preeclampsia. Subjects were group matched for prepregnancy body mass index (BMI) and race. Plasma homocysteine was analyzed by high pressure liquid chromatography (HPLC) with fluorescence detection, and plasma folic acid was measured by radio immunoassay (RIA).
  
  
  RESULTS
  The mean plasma concentration of homocysteine was significantly increased in all women with preeclampsia (7.4+/-2.9 microM) compared to all normal pregnant women (5.9+/-2.1 microM, p=0.002). However, homocysteine was not significantly increased in all women with twins (6.7+/-2.1 microM) compared to all women with singleton pregnancies (6.5+/-2.7 microM, p=0.61). In addition, women with twins and preeclampsia did not have increased homocysteine (6.8+/-2.1 microM) compared to women with twins and normal pregnancy (6.7+/-2.1 microM, p=0.72). As expected, because of extra supplementation, plasma folic acid was significantly increased in women with twins (27.9+/-11.6 ng/mL) compared to women with singleton pregnancies (20.8+/-8.5 ng/mL, p=0.0003). However, folic acid was not different between preeclamptics and controls (23.5+/-10.8 vs. 21.9+/-9.2 ng/mL respectively, p=0.36). Lastly, there was a significant inverse correlation between homocysteine and folic acid among all the subjects (r2=- 0.053, p< 0.01), and this correlation persisted in the women with singleton pregnancies (r2=- 0.078, p< 0.01), but was lost in the twins (r2=- 0.073, p=0.14).
  
  
  CONCLUSIONS
  With contemporary management including increased folic acid supplementation, plasma homocysteine is not increased in twin pregnancies with or without preeclampsia.
authors.affiliation: Magee-Womens Research Institute and Department of Obstetrics & Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, 204 Craft Ave., Room 620, 15213, Pittsburgh, Pennsylvania 15213, USA. rsirwp@mwri.magee.edu
authors.forename: Robert W
authors.initials: RW
authors.lastname: Powers
authors.forename: Michael S
authors.initials: MS
authors.lastname: Dunbar
authors.forename: Hannele M
authors.initials: HM
authors.lastname: Laivuori
authors.forename: Gail F
authors.initials: GF
authors.lastname: Harger
authors.forename: David L
authors.initials: DL
authors.lastname: Lykins
authors.forename: James M
authors.initials: JM
authors.lastname: Roberts
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005492:Folic Acid / Q000097:blood* / Q000378:metabolism; D005865:Gestational Age; D006710:Homocysteine / Q000097:blood* / Q000378:metabolism; D006801:Humans; D010298:Parity; D011247:Pregnancy; D011256:Pregnancy Outcome; D011272:Pregnancy, Multiple / Q000097:blood*; D011295:Prenatal Care; D011336:Probability; D012016:Reference Values; D012680:Sensitivity and Specificity; D014427:Twins
chemical_list: D015415:Biomarkers; D006710:Homocysteine; D005492:Folic Acid