title: Maternal underweight status and association with preterm contractions.
abstract: OBJECTIVE
  The purpose of the study is to investigate whether underweight pregnant women are more likely to be admitted for preterm contractions compared to normal or overweight women.
  
  
  METHODS
  This is a retrospective, cohort study of patients who presented for preterm contractions from January 1, 2000, through January 1, 2008. Body mass index(BMI) categories include index rating of ·19 as underweight,20–25 as normal, and >25 as overweight, based on the National Institutes of Health standards. Preterm contractions were documented using an external tocodynamometer.Exclusion criteria included multiple gestations,gestational age under 24 weeks or over 37 weeks, neonatal anomalies, and premature rupture of membrane. Data was analyzed using SPSS 14.0. Statistical data was analyzed using a probability model. 2 testing compared the probability of admission as a function of weight groups as well as age and race variables.
  
  
  RESULTS
  Of the 840 patients identified with preterm contractions,7% were admitted while 93% were discharged.Of the total patients, 15% were underweight, 43% normal weight, and 42% overweight. Admission for preterm contractions was highest in underweight pregnant women(95%), followed by normal weight (5%). None were overweight.Both basic and augmented probability models showed that normal weight patients were less likely to be admitted for preterm contractions compared to underweight patients even after controlling for age and race.
  
  
  CONCLUSIONS
  These results suggest that underweight patients are more likely to be admitted for preterm contractions compared to normal weight patients. No overweight patients were admitted for preterm contractions.
authors.affiliation: Department of Obstetrics and Gynecology, St. Joseph Hospital, Chicago, IL 60657, USA. maria.tam@reshealthcare.org
authors.forename: Teresa
authors.initials: T
authors.lastname: Tam
authors.forename: Michael
authors.initials: M
authors.lastname: Muresan
authors.forename: Neal
authors.initials: N
authors.lastname: Ipema
mesh_terms: D015992:Body Mass Index; D016009:Chi-Square Distribution; D005260:Female; D006760:Hospitalization; D006801:Humans; D007752:Obstetric Labor, Premature / Q000209:etiology*; D050177:Overweight / Q000150:complications; D011247:Pregnancy; D011336:Probability; D012189:Retrospective Studies; D013851:Thinness / Q000150:complications*; D018590:Uterine Monitoring; D015430:Weight Gain / Q000502:physiology*