title: Trends in an obstetric patient population: an eighteen-year study.
abstract: OBJECTIVE
  Our goal was to evaluate various trends including gestational age, birth weight, and mode of delivery in an inner-city obstetric patient population delivered at a tertiary medical center.
  
  
  METHODS
  We used an 18-year computerized perinatal database collected prospectively since 1975 in an inner-city tertiary medical center. More than 63,500 deliveries from 1975 through 1992 were evaluated. Trends in gestational age, birth weight, and mode of delivery were investigated with Cox-Stuart, regression, and other trend analysis methods.
  
  
  RESULTS
  The number of deliveries increased from 2682 in 1975 to 4740 in 1991, an increase of 77%. The median maternal age has increased from 20 years in 1975 to 23 years in 1992 (p < 0.001). Overall, the mean gestational age has declined monotonically from 39.2 +/- 2.84 weeks in 1975 to 38.3 +/- 3.17 weeks in 1992 (p = 0.057). While the median and lower percentiles of birth weight for singleton births have declined, the 75th and higher percentiles of birth weight have increased during 18 years. Overall, the proportion of preterm births (< 37 completed weeks gestational age) has increased from 3.3% in 1975 to 7.8% in 1991 (p < 0.001). During this period the proportion of low-birth-weight infants (< 2,500 gm) increased significantly from 12.7% to 17.3% (p < 0.001). The proportion of cesarean section deliveries for private patients has declined from 37% in 1975 to 25% in 1992 (p = 0.025), while this proportion has increased monotonically for staff patients from 10% to 17% during this period (p < 0.001).
  
  
  CONCLUSIONS
  Considering the large size of the database and diverse background of the study population, we believe that these trends can provide a realistic characterization of an obstetric patient population for a large inner-city urban population.
authors.affiliation: Department of Epidemiology and Biostatistics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4945.
authors.forename: S B
authors.initials: SB
authors.lastname: Amini
authors.forename: L J
authors.initials: LJ
authors.lastname: Dierker
authors.forename: P M
authors.initials: PM
authors.lastname: Catalano
authors.forename: G G
authors.initials: GG
authors.lastname: Ashmead
authors.forename: L I
authors.initials: LI
authors.lastname: Mann
mesh_terms: D000293:Adolescent; D000328:Adult; D001724:Birth Weight; D002585:Cesarean Section / Q000639:trends; D036861:Delivery, Obstetric / Q000639:trends; D005006:Ethnicity; D005260:Female; D005865:Gestational Age; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007234:Infant, Premature; D007348:Insurance, Health / Q000639:trends; D008137:Longitudinal Studies; D008297:Male; D011247:Pregnancy / Q000706:statistics & numerical data*; D011446:Prospective Studies; D012044:Regression Analysis; D014504:Urban Health / Q000639:trends