title: The effect of regular leisure physical activity on birth outcomes.
abstract: OBJECTIVE
  The purpose of this study was to determine the effect of regular leisure physical activity (RLPA) on two different adverse birth outcomes: timeliness of delivery (<37 weeks, preterm; 37-42 weeks, term; and >42 weeks, postterm) and low birth weight (<1500 g, very low; 1500-2499 g, low).
  
  
  METHODS
  The present sample, consisting of 9089 women, was obtained from the 1988 National Maternal and Infant Health Survey (NMIHS) data. The NMIHS was developed to examine adverse birth outcomes by assessing various maternal characteristics such as demographic, behavioral, and health care factors not found in vital statistics data.
  
  
  RESULTS
  The specified adjusted models obtained by logistic regression indicate that women who failed to engage in RLPA before and during their pregnancy were more likely to give birth to a very low birth weight baby [OR = 1.75; 95% CI (1.50, 2.04)] but not to a low birth weight baby [OR = 1.15: 95% CI (0.99, 1.34)] compared with women who remained active before and during pregnancy. Moreover, previously active women who stopped physical activity during pregnancy were more likely to give birth to a low birth weight [OR = 1.28; 95% CI (1.05, 1.56)] or a very low birth weight [OR = 2.05; 95% CI (1.69, 2.48)] baby than women who remained active before and during pregnancy. There was no significant relationship between RLPA and timeliness of delivery. Similar results were found after controlling for maternal medical risk.
  
  
  CONCLUSIONS
  RLPA during pregnancy had no deleterious effect on birth outcomes among these women. RLPA may also reduce the risk of low birth weight outcomes.
authors.affiliation: Department of Human Nutrition, Foods, and Exercise, Virginia Tech University, Blacksburg, Virginia 24061, USA. jleif@vt.edu
authors.forename: Jenn A
authors.initials: JA
authors.lastname: Leiferman
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Evenson
mesh_terms: D000293:Adolescent; D000328:Adult; D003625:Data Collection; D015444:Exercise; D005260:Female; D005865:Gestational Age; D015438:Health Behavior; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007899:Leisure Activities; D007752:Obstetric Labor, Premature / Q000453:epidemiology; D016017:Odds Ratio; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D037841:Pregnant People / Q000523:psychology*; D012044:Regression Analysis; D012494:Sampling Studies; D012959:Socioeconomic Factors; D014481:United States / Q000453:epidemiology