Investigating Implausible Gestational Age and High Birthweight Combinations.

Area of Science:

• Perinatal epidemiology
• Reproductive health statistics
• Clinical data accuracy

Background:

• Birth certificate data often overestimate national preterm births due to errors in last menstrual period (LMP) dates.
• Investigating errors in birthweight and LMP date transfer to birth certificates is crucial for accurate gestational age assessment.
• High birthweight-for-gestational-age births are often implausible due to data inaccuracies.

Purpose of the Study:

• To quantify the extent of errors in birthweight and LMP date transfer to birth certificates.
• To determine the resolution rate of implausible births using clinical estimate (CE) versus LMP-based gestational age.
• To identify medical explanations for unresolved implausible birthweight-for-gestational-age cases.

Main Methods:

• Examined medical records and birth certificates for singleton infants with implausibly high birthweight-for-gestational-age.
• Focused on births within the Kaiser Permanente Northwest system (Oregon, 1998-2007).
• Calculated percentages of implausible records resolved under different data scenarios.

Main Results:

• Identified 100 births with implausibly high birthweight-for-gestational age combinations.
• Using medical record data resolved 31% of implausible births.
• Substituting birth certificate CE for LMP date resolved 92% of implausible births, with 72% having early pregnancy clinical estimates.

Conclusions:

• Utilizing the birth certificate's clinical estimate (CE) over LMP data significantly improves the accuracy of classifying birthweight-for-gestational-age.
• The CE provides a clinically reliable reclassification for most implausible deliveries.
• Further investigation is needed for the few unresolved cases, with maternal diabetes noted in some.