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 34⁰/₇ to 36⁶/₇ 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.

KEYWORDS

Age - hypertensive disease - diabetes - teenage pregnancy - advance maternal age

REFERENCES

• 1 Damus K. Prevention of preterm birth: a renewed national priority.  Curr Opin Obstet Gynecol. 2008;  20 590-596
• 2 Danel I, Berg C, Johnson C H, Atrash H. Magnitude of maternal morbidity during labor and delivery: United States, 1993–1997.  Am J Public Health. 2003;  93 631-634
• 3 Steer P J. The epidemiology of preterm labour—why have advances not equated to reduced incidence?.  BJOG. 2006;  113 (Suppl 3) 1-3
• 4 Holland M G, Refuerzo J S, Ramin S M, Saade G R, Blackwell S C. Late preterm birth: how often is it avoidable?.  Am J Obstet Gynecol. 2009;  201 404 e1-e4
• 5 Khashu M, Narayanan M, Bhargava S, Osiovich H. Perinatal outcomes associated with preterm birth at 33 to 36 weeks' gestation: a population-based cohort study.  Pediatrics. 2009;  123 109-113
• 6 Loftin R W, Habli M, Snyder C C, Cormier C M, Lewis D F, Defranco E A. Late preterm birth.  Rev Obstet Gynecol. 2010;  3 10-19
• 7 Hosmer D W, Lemeshow S. Applied Logistic Regression, 2nd ed. New York: Wiley; 2000
• 8 Sakamoto Y, Ishiguro M, Kitagawa G. Akaike Information Criterion Statistics. Dordrecht, Holland: D. Reidel Publishing Company; 1986
• 9 Clark S L, Miller D D, Belfort M A, Dildy G A, Frye D K, Meyers J A. Neonatal and maternal outcomes associated with elective term delivery.  Am J Obstet Gynecol. 2009;  200 156 e1-e4
• 10 Clark S L, Frye D R, Meyers J A et al.. Reduction in elective delivery at <39 weeks of gestation: comparative effectiveness of 3 approaches to change and the impact on neonatal intensive care admission and stillbirth.  Am J Obstet Gynecol. 2010;  203 449
• 11 Talge N M, Holzman C, Wang J, Lucia V, Gardiner J, Breslau N. Late-preterm birth and its association with cognitive and socioemotional outcomes at 6 years of age.  Pediatrics. 2010;  126 1124-1131
• 12 Park Y W, Zhu S, Palaniappan L, Heshka S, Carnethon M R, Heymsfield S B. The metabolic syndrome: prevalence and associated risk factor findings in the US population from the Third National Health and Nutrition Examination Survey, 1988–1994.  Arch Intern Med. 2003;  163 427-436
• 13 Walker S E, Gurka M J, Oliver M N, Johns D W, Deboer M D. Racial/ethnic discrepancies in the metabolic syndrome begin in childhood and persist after adjustment for environmental factors.  Nutr Metab Cardiovasc Dis. 2010;  (August) 11 (Epub ahead of print)
• 14 Thornburg K L, Shannon J, Thuillier P, Turker M S. In utero life and epigenetic predisposition for disease.  Adv Genet. 2010;  71 57-78
• 15 Jacobsson B, Ladfors L, Milsom I. Advanced maternal age and adverse perinatal outcome.  Obstet Gynecol. 2004;  104 727-733
• 16 Delpisheh A, Brabin L, Attia E, Brabin B J. Pregnancy late in life: a hospital-based study of birth outcomes.  J Womens Health (Larchmt). 2008;  17 965-970
• 17 Ikramullah E, Schelar E, Manlove J, Moore K A. Facts at a glance: a fact sheet reporting national, state-level, and city-level trends in teen childbearing. Child Trends 2007.
• 18 Chen X K, Wen S W, Fleming N, Demissie K, Rhoads G G, Walker M. Teenage pregnancy and adverse birth outcomes: a large population based retrospective cohort study.  Int J Epidemiol. 2007;  36 368-373
• 19 Nielsen J N, Gittelsohn J, Anliker J, O'Brien K. Interventions to improve diet and weight gain among pregnant adolescents and recommendations for future research.  J Am Diet Assoc. 2006;  106 1825-1840
• 20 Hamilton B E, Martin J A, Ventura S J. Births: Preliminary data for 2007. National Vital Statistics Reports. Vol. 57, No. 12. Hyattsville, MD: National Center for Health Statistics. Released March 18, 2009. Available at: http://www.cdc.gov/nchs/data/nvsr/nvsr57/nvsr57_12.pdf