title: Serum vitamin B12 levels during the first trimester of pregnancy correlate with newborn screening markers of vitamin B12 deficiency.
abstract: BACKGROUND
  Low maternal vitamin B12 status is a risk factor for various adverse pregnancy outcomes. Although vitamin B12 deficiency is not a primary target of newborn screening (NBS) programs, measurements of propionylcarnitine (C3) and its ratios with acetylcarnitine (C3/C2) and palmitoylcarnitine (C3/C16) may incidentally identify vitamin B12-deficient newborns. The objective of this study was to measure vitamin B12 levels in women during the first trimester of pregnancy, evaluate predictors of these concentrations, and study their relationship with newborn screening results.
  
  
  METHODS
  Vitamin B12 concentrations were evaluated in 204 women during the first trimester of pregnancy and possible confounding factors were analyzed. After giving birth, data of their newborns (189) were collected (sex, gestational age, birthweight) and the acylcarnitine profile obtained by tandem mass spectrometry during NBS was analyzed. To assess the effects of the variables on vitamin B12 serum concentrations and newborn screening markers, stepwise multiple linear regression models were used.
  
  
  RESULTS
  The mean serum concentration of vitamin B12 was 370.8 pmol/L (502.4 pg/mL) (SD 142.81). Vitamin B12 concentrations were significantly lower in smokers (p=0.027), and in women with low meat consumption (p=0.040). There was a significant inverse correlation between mothers' vitamin B12 concentrations and their children's C3 (r=-0.24; p=0.001), C3/C2 (r=-0.23; p=0.002) and C3/C16 levels (r=-0.20; p=0.006).
  
  
  CONCLUSIONS
  Newborn screening markers (C3, C3/C2, and C3/C16) present an inverse correlation with maternal vitamin B12 status in the first trimester of pregnancy. Regarding factors that may influence maternal serum vitamin B12 levels during the first trimester, smoking seems to have a negative effect, and meat consumption a positive effect.
authors.affiliation: Clinical Laboratory and Oriental Andalucia Newborn Screening Center, Málaga Regional Hospital, Málaga, Spain.
authors.forename: Anita
authors.initials: A
authors.lastname: Dayaldasani
authors.affiliation: Clinical Laboratory and Oriental Andalucia Newborn Screening Center, Málaga Regional Hospital, Málaga, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Ruiz-Escalera
authors.affiliation: Clinical Laboratory and Oriental Andalucia Newborn Screening Center, Málaga Regional Hospital, Málaga, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Rodríguez-Espinosa
authors.affiliation: Clinical Laboratory and Oriental Andalucia Newborn Screening Center, Málaga Regional Hospital, Málaga, Spain.
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Rueda
authors.affiliation: Clinical Laboratory and Oriental Andalucia Newborn Screening Center, Málaga Regional Hospital, Málaga, Spain.
authors.forename: Vidal
authors.initials: V
authors.lastname: Pérez-Valero
authors.affiliation: Clinical Laboratory and Oriental Andalucia Newborn Screening Center, Málaga Regional Hospital, Málaga, Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: Yahyaoui
mesh_terms: D000108:Acetylcarnitine / Q000097:blood; D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood*; D002331:Carnitine / Q000031:analogs & derivatives / Q000097:blood; D004032:Diet; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008429:Maternal Welfare; D008460:Meat; D015997:Neonatal Screening; D009752:Nutritional Status; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood; D011263:Pregnancy Trimester, Third; D012907:Smoking / Q000009:adverse effects / Q000097:blood; D014805:Vitamin B 12 / Q000097:blood*; D014806:Vitamin B 12 Deficiency / Q000097:blood*; D055815:Young Adult
chemical_list: D015415:Biomarkers; C003223:propionylcarnitine; D000108:Acetylcarnitine; D014805:Vitamin B 12; D002331:Carnitine
keywords: newborn screening; pregnancy; propionylcarnitine; vitamin B12