title: Periconceptional maternal one-carbon biomarkers are associated with embryonic development according to the Carnegie stages.
abstract: Is periconceptional maternal one-carbon (I-C) metabolism associated with embryonic morphological development in non-malformed ongoing pregnancies?
  
  
  
  Serum vitamin B12, red blood cell (RBC) folate and plasma total homocysteine (tHcy) are associated with embryonic development according to the Carnegie stages.
  
  
  
  Derangements in maternal I-C metabolism affect reproductive and pregnancy outcomes, as well as future health of the offspring.
  
  
  
  Between 2010 and 2014, women with singleton ongoing pregnancies were enrolled in a prospective periconceptional cohort study.
  
  
  
  A total of 234 pregnancies, including 138 spontaneous or IUI pregnancies with strict pregnancy dating and 96 pregnancies derived from IVF, ICSI or cryopreserved embryo transfer (IVF/ICSI pregnancies), underwent longitudinal transvaginal three-dimensional ultrasound (3D US) scans from 6+0 up to 10+2 weeks of gestation. Carnegie stages were defined using internal and external morphologic criteria in a virtual reality system. Maternal venous blood samples were collected at enrollment for serum vitamin B12, RBC folate and plasma tHcy assessment. Associations between biomarker concentrations and longitudinal Carnegie stages were investigated using linear mixed models.
  
  
  
  We performed a median of three 3D US scans per pregnancy (range 1-5) resulting in 600 good quality data sets for the Carnegie stage annotation (80.5%). Vitamin B12 was positively associated with embryonic development in the total study population (β = 0.001 (95% CI: 0.000; 0.002), P < 0.05) and in the subgroup of strictly dated spontaneous pregnancies (β = 0.002 (95% CI: 0.001; 0.003), P < 0.05). Low vitamin B12 concentrations (-2SD, 73.4 pmol/l) were associated with delayed embryonic development by 1.4 days (95% CI: 1.3-1.4) compared with high concentrations (+2SD, 563.1 pmol/l). RBC folate was positively associated with Carnegie stages only in IVF/ICSI pregnancies (β = 0.001 (95% CI: 0.0005; 0.0015), P < 0.05). In this group, low RBC folate concentrations (-2SD, 875.4 nmol/l) were associated with a 1.8-day delay (95% CI: 1.7-1.8) in development compared with high concentrations (+2SD, 2119.9 nmol/l). tHcy was negatively associated with embryonic development in the total study population (β = -0.08 (95% CI: -0.14; -0.02), P < 0.01), as well as in the IVF/ICSI subgroup (β = -0.08 (95% CI: -0.15; -0.01), P < 0.05). High tHcy concentrations (+2SD, 10.4 µmol/l) were associated with a delay of 1.6 days (95% CI: 1.5-1.7) in embryonic development compared with low concentrations (-2SD, 3.0 µmol/l).
  
  
  
  The study was performed in a tertiary care center, resulting in high rates of folic acid supplement use and comorbidity that may reduce the external validity of our findings.
  
  
  
  In periconceptional care, maternal I-C biomarkers should be taken into account as predictors of embryonic morphological development. Combining embryonic size measurements with morphological assessment could better define normal embryonic development.
  
  
  
  The work was funded by the Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands. RPMST is CSO of the startup company Slimmere Zorg and CEO of eHealth Care Solutions. The authors declare no conflicts of interest.
  
  
  
  Not applicable.
authors.affiliation: Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Centre, PO Box 2040, 3000CA Rotterdam, The Netherlands.
authors.forename: F
authors.initials: F
authors.lastname: Parisi
authors.affiliation: Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Centre, PO Box 2040, 3000CA Rotterdam, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Rousian
authors.affiliation: Department of Bioinformatics, Erasmus MC, University Medical Centre, PO Box 2040, 3000CA Rotterdam, The Netherlands.
authors.forename: A H J
authors.initials: AH
authors.lastname: Koning
authors.affiliation: Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Centre, PO Box 2040, 3000CA Rotterdam, The Netherlands.|Department of Biostatistics, Erasmus MC, University Medical Centre, PO Box 2040, 3000CA Rotterdam, The Netherlands.
authors.forename: S P
authors.initials: SP
authors.lastname: Willemsen
authors.affiliation: Centre for Fetal Research Giorgio Pardi, Department of Biomedical and Clinical Sciences, Hospital Luigi Sacco, Università degli Studi di Milano, Via G.B. Grassi 74, 20157 Milan, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Cetin
authors.affiliation: Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Centre, PO Box 2040, 3000CA Rotterdam, The Netherlands.|Department of Pediatrics, Division of Neonatology, Erasmus MC, University Medical Centre, PO Box 2040, 3000CA Rotterdam, The Netherlands.
authors.forename: R P M
authors.initials: RP
authors.lastname: Steegers-Theunissen
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D018568:Crown-Rump Length; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D005492:Folic Acid / Q000097:blood*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D011247:Pregnancy; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal; D014805:Vitamin B 12 / Q000097:blood*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D006710:Homocysteine; D005492:Folic Acid; D014805:Vitamin B 12
keywords: Carnegie stage; folate; homocysteine; maternal one-carbon metabolism; vitamin B12