title: Extreme maternal underweight and feto-infant morbidity outcomes: a population-based study.
abstract: OBJECTIVE
  We sought to estimate the association between severity of maternal pre-pregnancy underweight and feto-infant morbidity outcomes.
  
  
  METHODS
  Missouri maternally linked cohort records from 1989 to 1997 inclusive were analysed. Using pre-pregnancy maternal body mass index (BMI), we classified study participants into: Normal (18.5-24.9) [referent group], mild thinness (17.0-18.5), moderate thinness (16.0-16.9) and severe thinness (<16.0). We estimated the association between pre-pregnancy underweight, underweight subtypes and feto-infant morbidity outcomes using adjusted odds ratios to approximate relative risks with correction for intra-cluster correlations.
  
  
  RESULTS
  Fetal growth curve trajectories for the two groups became divergent as from 30 gestational weeks. Underweight mothers were at increased risk for low birthweight (OR = 1.82; 95% CI = 1.77-1.88), very low birthweight (OR = 1.41; 95% CI = 1.31-1.51), small for gestational age (OR = 1.80; 95% CI = 1.76-1.84), preterm (OR = 1.37; 95% CI = 1.33-1.40) and very preterm (OR = 1.42; 95% CI = 1.34-1.50). These risk estimates increased in a dose-effect fashion with increasing severity of underweight status except for very preterm (p for trend < 0.01).
  
  
  CONCLUSIONS
  Pre-pregnancy underweight is a risk factor for a spectrum of feto-infant morbidity outcomes, with risk estimates being most pronounced among extremely underweight mothers.
authors.affiliation: The Chiles Centre for Healthy Mothers and Babies, University of South Florida, Tampa, Florida 33613, USA. hamisu.salihu@gmail.com
authors.forename: Hamisu M
authors.initials: HM
authors.lastname: Salihu
authors.forename: O'Neil
authors.initials: O
authors.lastname: Lynch
authors.forename: Amina P
authors.initials: AP
authors.lastname: Alio
authors.forename: Alfred K
authors.initials: AK
authors.lastname: Mbah
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Kornosky
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Marty
mesh_terms: D000328:Adult; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D005315:Fetal Diseases / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000453:epidemiology* / Q000209:etiology; D008431:Maternal-Fetal Exchange / Q000502:physiology; D009017:Morbidity; D009035:Mothers / Q000706:statistics & numerical data; D007744:Obstetric Labor Complications / Q000453:epidemiology / Q000209:etiology; D011153:Population; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D011256:Pregnancy Outcome; D015995:Prevalence; D013851:Thinness / Q000150:complications*; D055815:Young Adult