title: Maternal vitamin D deficiency and fetal distress/birth asphyxia: a population-based nested case-control study.
abstract: OBJECTIVE
  Vitamin D deficiency causes not only skeletal problems but also muscle weakness, including heart muscle. If the fetal heart is also affected, it might be more susceptible to fetal distress and birth asphyxia. In this pilot study, we hypothesised that low maternal vitamin D levels are over-represented in pregnancies with fetal distress/birth asphyxia.
  
  
  METHODS
  A population-based nested case-control study.
  
  
  METHODS
  Banked sera of 2496 women from the 12th week of pregnancy.
  
  
  METHODS
  Vitamin D levels were analysed using a direct competitive chemiluminescence immunoassay. Vitamin D levels in early gestation in women delivered by emergency caesarean section due to suspected fetal distress were compared to those in controls. Birth asphyxia was defined as Apgar <7 at 5 min and/or umbilical cord pH≤7.15.
  
  
  RESULTS
  Vitamin D levels were significantly lower in mothers delivered by emergency caesarean section due to suspected fetal distress (n=53, 43.6±18 nmol/L) compared to controls (n=120, 48.6±19 nmol/L, p=0.04). Birth asphyxia was more common in women with vitamin D deficiency (n=95) in early pregnancy (OR 2.4, 95% CI 1.1 to 5.7).
  
  
  CONCLUSIONS
  Low vitamin D levels in early pregnancy may be associated with emergency caesarean section due to suspected fetal distress and birth asphyxia. If our findings are supported by further studies, preferably on severe birth asphyxia, vitamin D supplementation/sun exposure in pregnancy may lower the risk of subsequent birth asphyxia.
authors.affiliation: Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden Department of Obstetrics & Gynecology, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Pelle G
authors.initials: PG
authors.lastname: Lindqvist
authors.affiliation: Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Aldo T
authors.initials: AT
authors.lastname: Silva
authors.affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Sven A
authors.initials: SA
authors.lastname: Gustafsson
authors.affiliation: Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden Department of Obstetrics & Gynecology, Karolinska University Hospital, Stockholm, Sweden Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Gidlöf
keywords: OBSTETRICS