title: Is hyperemesis gravidarum associated with placental weight and the placental weight-to-birth weight ratio? A population-based Norwegian cohort study.
abstract: BACKGROUND
  Studies have suggested a link between placental weight, placental weight-to-birth weight ratio (PW/BW) and adult health. Hyperemesis gravidarum (HG) may also have implications for adult health. No studies on HG and placental characteristics have been identified. We therefore explored the relationship between HG, placental weight and the PW/BW-ratio in a population-based cohort.
  
  
  METHODS
  Singleton births to primiparous women between 1999 and 2009 with data on HG, placental weight and birth weight in the Medical Birth Registry of Norway (MBRN) comprised the study base (n = 200,390). HG was defined through ICD-10 code 021.0, 021.1 and 021.9. Gender and gestational age specific percentile curves for placenta weight and PW/BW ratio were used to define those below the 10th and above the 90th percentile of both outcomes. Associations between HG and dichotomous outcomes were studied by multiple logistic regression. Multiple linear regression was applied to study placental weight as a continuous variable. Male and female offspring were analyzed separately.
  
  
  RESULTS
  The prevalence of HG was 1.2%. Women with HG and female offspring had significantly higher risk of a PW/BW-ratio above the 90th percentile (OR = 1.17, 95% CI: 1.03-1.34). HG and PW/BW-ratio below the 10th percentile were inversely associated (OR = 0.70, 95% CI: 0.56-0.89). For male offspring no association was observed for HG and PW/BW-ratio below the 10th or above the 90th percentile.
  
  
  CONCLUSIONS
  We observed positive associations between HG and high PW/BW ratio limited to female offspring only. The high PW/BW-ratio suggests that there may be a possible link between HG and adult health.
authors.affiliation: Division for Epidemiology, Norwegian Institute of Public Health, PO Box 4404, Nydalen, 0403 Oslo, Norway; Norwegian Resource Centre for Women's Health, Oslo Universitetssykehus HF, Rikshospitalet, PO Box 4950, Nydalen, 0424 Oslo, Norway. Electronic address: kafv@fhi.no.
authors.forename: K F
authors.initials: KF
authors.lastname: Vandraas
authors.forename: Å V
authors.initials: ÅV
authors.lastname: Vikanes
authors.forename: N C
authors.initials: NC
authors.lastname: Støer
authors.forename: S
authors.initials: S
authors.lastname: Vangen
authors.forename: P
authors.initials: P
authors.lastname: Magnus
authors.forename: A M
authors.initials: AM
authors.lastname: Grjibovski
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers; D001724:Birth Weight; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D047109:Fetal Development; D006801:Humans; D006939:Hyperemesis Gravidarum / Q000453:epidemiology / Q000473:pathology*; D007231:Infant, Newborn; D008297:Male; D009664:Norway / Q000453:epidemiology; D009929:Organ Size; D010920:Placenta / Q000473:pathology*; D010929:Placentation; D011247:Pregnancy; D015995:Prevalence; D012042:Registries; D012306:Risk; D012727:Sex Characteristics; D055815:Young Adult
chemical_list: D015415:Biomarkers
keywords: Hyperemesis gravidarum; PW/BW-ratio; Placental weight; Population-based cohort