Does gestational age misclassification explain the difference in birthweights for Australian aborigines and whites?

Area of Science:

• Perinatal epidemiology
• Biostatistics
• Population health

Background:

• Summary birthweight measures show slower growth for Australian Aboriginals and US Blacks compared to white populations after 34 weeks gestation.
• Observed patterns suggest potential disparities in fetal growth and development between ethnic groups.

Purpose of the Study:

• To investigate if differential misclassification of gestational age explains the observed slower-than-expected birthweight gains in Australian Aboriginal infants.
• To assess the impact of gestational age misclassification on birthweight distribution parameters.

Main Methods:

• Utilized simulation modeling to evaluate the effect of gestational age misclassification on birthweight distributions.
• Employed data from the Queensland Perinatal Data Collection (QPDC) for reported gestational ages.
• Incorporated previous studies and QPDC data to define birthweight distributions for simulations, considering various misclassification scenarios.

Main Results:

• Birthweight distribution parameters at term were largely unaffected by gestational age misclassification.
• The 10th centiles of birthweight remained robust to misclassification at preterm.
• The 90th centiles demonstrated sensitivity to even minor gestational age misclassification.
• Significant misclassification was needed to eliminate the observed divergence in median birthweights between Aboriginal and white infants.

Conclusions:

• Differential gestational age misclassification is an improbable cause for the divergence in average birthweights between Australian Aboriginal and white infants.
• Findings suggest that other factors likely contribute to the observed birthweight disparities.
• The study provides insights for interpreting birthweight comparisons across different populations.