International comparisons of preterm birth: higher rates of late preterm birth are associated with lower rates of stillbirth and neonatal death

Authors

  • S Lisonkova,

    1. Department of Obstetrics and Gynaecology, University of British Columbia and the Women’s Hospital and Health Centre of British Columbia, Vancouver, BC, Canada
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  • Y Sabr,

    1. Department of Obstetrics and Gynaecology, University of British Columbia and the Women’s Hospital and Health Centre of British Columbia, Vancouver, BC, Canada
    2. Department of Obstetrics and Gynaecology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
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  • B Butler,

    1. Department of Obstetrics and Gynaecology, University of British Columbia and the Women’s Hospital and Health Centre of British Columbia, Vancouver, BC, Canada
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  • KS Joseph

    1. Department of Obstetrics and Gynaecology, University of British Columbia and the Women’s Hospital and Health Centre of British Columbia, Vancouver, BC, Canada
    2. School of Population and Public Health, University of British Columbia, Vancouver, BC, Canada
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Dr S Lisonkova, Department of Obstetrics and Gynaecology, Women’s Hospital and Health Centre of British Columbia, Room E418B, 4480 Oak Street, Vancouver, BC, Canada, V6H 3V4. Email slisonkova@cfri.ca

Abstract

Please cite this paper as: Lisonkova S, Sabr Y, Butler B, Joseph K. International comparisons of preterm birth: higher rates of late preterm birth are associated with lower rates of stillbirth and neonatal death. BJOG 2012;119:1630–1639.

Objective  To examine international rates of preterm birth and potential associations with stillbirths and neonatal deaths at late preterm and term gestation.

Design  Ecological study.

Setting  Canada, USA and 26 countries in Europe.

Population  All deliveries in 2004.

Methods  Information on preterm birth (<37, 32–36, 28–31 and 24–27 weeks of gestation) and perinatal deaths was obtained for 28 countries. Data sources included files and publications from Statistics Canada, the EURO-PERISTAT project and the National Center for Health Statistics. Pearson correlation coefficients and random-intercept Poisson regression were used to examine the association between preterm birth rates and gestational age-specific stillbirth and neonatal death rates. Rate ratios with 95% confidence intervals were estimated after adjustment for maternal age, parity and multiple births.

Main outcome measures  Stillbirths and neonatal deaths ≥32 and ≥37 weeks of gestation.

Results  International rates of preterm birth (<37 weeks) ranged between 5.3 and 11.4 per 100 live births. Preterm birth rates at 32–36 weeks were inversely associated with stillbirths at ≥32 weeks (adjusted rate ratio 0.94, 95% CI 0.92–0.96) and ≥37 weeks (adjusted rate ratio 0.88, 95% CI 0.85–0.91) of gestation and inversely associated with neonatal deaths at ≥32 weeks (adjusted rate ratio 0.88, 95% CI 0.85–0.91) and ≥37 weeks (adjusted rate ratio 0.82, 95% CI 0.78–0.86) of gestation.

Conclusions  Countries with high rates of preterm birth at 32–36 weeks of gestation have lower stillbirth and neonatal death rates at and beyond 32 weeks of gestation. Contemporary rates of preterm birth are indicators of both perinatal health and obstetric care services.

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