When is birthweight at term abnormally low? A systematic review and meta-analysis of the association and predictive ability of current birthweight standards for neonatal outcomes
Article first published online: 8 JAN 2014
© 2014 The Authors BJOG An International Journal of Obstetrics and Gynaecology published by John Wiley & Sons Ltd on behalf of Royal College of Obstetricians and Gynaecologists
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BJOG: An International Journal of Obstetrics & Gynaecology
Volume 121, Issue 5, pages 515–526, April 2014
How to Cite
When is birthweight at term abnormally low? A systematic review and meta-analysis of the association and predictive ability of current birthweight standards for neonatal outcomes. BJOG 2014;121:515–526., , , , .
- Issue published online: 18 MAR 2014
- Article first published online: 8 JAN 2014
- Manuscript Accepted: 20 SEP 2013
- Mary Crosse Fellowship, Birmingham Womens' Hospital
- Fetal growth restriction;
- low birthweight;
- neonatal morbidity;
- neonatal mortality;
- systematic review
Intrauterine growth restriction is a cause of neonatal morbidity and mortality. A variety of definitions of low birthweight are used in clinical practice, with a lack of consensus regarding which definitions best predict adverse outcomes.
To evaluate the relationship between birthweight standards and neonatal outcome in term-born infants (at ≥ 37 weeks of gestation).
MEDLINE (1966–January 2011), EMBASE (1980–January 2011), and the Cochrane Library (2011:1) and MEDION were included in our search.
Studies comprising live term-born infants (gestation ≥ 37 completed weeks), with weight or other anthropometric measurements recorded at birth along with neonatal outcomes.
Data collection and analysis
Data were extracted to populate 2 × 2 tables relating birthweight standard with outcome, and meta-analysis was performed where possible.
Twenty-nine studies including 21 034 114 neonates were selected. Absolute birthweight was strongly associated with mortality, with birthweight < 1.5 kg giving the largest association (OR 48.6, 95% CI 28.62–82.53). When using centile charts, regardless of threshold, the summary odds ratios were significant but closer to 1 than when using absolute birthweight. For all tests, summary predictive ability comprised high specificity and positive likelihood ratio for neonatal death, but low sensitivity and a negative likelihood ratio close to 1.
Absolute birthweight is a prognostic factor for neonatal mortality. The indirect evidence suggests that centile charts or other definitions of low birthweight are not as strongly associated with mortality as the absolute birthweight. Further research is required to improve predictive accuracy.