title: The late preterm birth rate and its association with comorbidities in a population-based study.
abstract: We sought to identify rates, associated morbidities, and preventable causes of late preterm birth (LPB) in a defined population. We conducted a retrospective cross-sectional analysis using deidentified delivery data for all who delivered in San Antonio/Bexar County, Texas between 2000 and 2008 (N  = 259,576). LPB was defined as a live birth from 34(0/7) to 36(6/7) weeks. Variables analyzed included age, race/ethnicity, weight gain, hypertensive disease, diabetes, and preterm labor including premature rupture of membranes. From 2000 to 2006, the LPB rate in San Antonio/Bexar County, Texas, was slightly higher than the national average, 9% versus 8.7% (P  < 0.01). From 2000 to 2008, 23,312 LPBs occurred in San Antonio/Bexar County and 53% experienced at least one studied comorbidity. Using logistic regression comparing LPB to term, variables associated with an increased risk of LPB were black race, age < 17, age ≥ 35, gestational hypertension, eclampsia, chronic hypertension, and diabetes. LPB was higher than the national average in our population, and preventable causes of LPB (extremes of age, hypertensive disease, and diabetes) were commonly associated with LPB. We speculate that teenage pregnancy prevention, counseling regarding risks associated with advanced maternal age, and improved management and prevention of hypertensive disease and diabetes should prove beneficial in decreasing the LPB rate.
authors.affiliation: Department of Obstetrics/Gynecology, University of Health Science Center at San Antonio, San Antonio, Texas 78229, USA. cartermf@uthscsa.edu
authors.forename: Margaret F
authors.initials: MF
authors.lastname: Carter
authors.forename: Sharon
authors.initials: S
authors.lastname: Fowler
authors.forename: Alan
authors.initials: A
authors.lastname: Holden
authors.forename: Elly
authors.initials: E
authors.lastname: Xenakis
authors.forename: Donald
authors.initials: D
authors.lastname: Dudley
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data; D003430:Cross-Sectional Studies; D003920:Diabetes Mellitus / Q000453:epidemiology; D004461:Eclampsia / Q000453:epidemiology; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000453:epidemiology; D046110:Hypertension, Pregnancy-Induced / Q000453:epidemiology; D016015:Logistic Models; D008423:Maternal Age; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D047928:Premature Birth / Q000453:epidemiology* / Q000208:ethnology / Q000209:etiology*; D012189:Retrospective Studies; D012307:Risk Factors; D013781:Texas / Q000453:epidemiology; D015430:Weight Gain; D055815:Young Adult