Controlling for Gestational Age in Birth Weight Studies
Author Information
Author(s): Jørn Olsen, Chunyuan Fei
Primary Institution: University of California, Los Angeles
Hypothesis
How does gestational age estimation affect the analysis of birth weights?
Conclusion
Misclassification of gestational age can significantly impact the analysis of birth weights, but the authors found that the effect of large random errors is more pronounced than smaller systematic errors.
Supporting Evidence
- LMP estimates are prone to large random measurement errors.
- Ultrasound measures assume uniform early fetal growth, which may not always be correct.
- The study found that large random errors of gestational age affect estimates more than smaller systematic errors.
Takeaway
When scientists study how chemicals affect babies, they have to guess how far along the pregnancy is, and sometimes these guesses can be really wrong, which can change the results.
Methodology
The study compared regression coefficients based on last menstrual period (LMP) estimates and ultrasound-based gestational age adjustments.
Potential Biases
There is a risk of bias due to the imprecise measures of gestational age affecting the results.
Limitations
The estimates of gestational age are prone to misclassification and measurement errors.
Statistical Information
Confidence Interval
−20.6 to −0.15
Digital Object Identifier (DOI)
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