A New Approach to Developing Birth Weight Reference Charts: A Retrospective Observational Study.

Area of Science:

• Perinatal Medicine
• Neonatal Research
• Maternal-Fetal Medicine

Background:

• Current birth weight reference charts exhibit bias in preterm gestations due to the inclusion of births associated with abnormal growth.
• Many preterm births are linked to underlying growth disturbances, impacting the accuracy of historical reference data.

Purpose of the Study:

• To develop more accurate birth weight reference charts by utilizing data exclusively from spontaneous onset of labor births.
• To assess the impact of excluding iatrogenic births on the construction of birth weight centile charts.

Main Methods:

• A single-center retrospective observational study included 115,712 singleton live births.
• Births were categorized as spontaneous or iatrogenic, with quantile regression modeling birth weight in relation to gestational age, sex, and labor onset.
• Birth weights from spontaneous and iatrogenic cohorts were compared by gestation and to existing ultrasound-based charts.

Main Results:

• Significant differences in birth weights were observed between spontaneous and iatrogenic births at the median and 10th centiles across gestations.
• Preterm infants born via iatrogenic delivery weighed less than their spontaneous preterm counterparts.
• Birth weight centiles derived from spontaneous births closely aligned with established ultrasound-based curves.

Conclusions:

• Iatrogenic births are frequently associated with pre-existing fetal growth disturbances, significantly influencing standard centile charts.
• Excluding iatrogenic births from reference chart creation provides a more accurate representation of normal fetal growth.
• Birth weight charts based solely on spontaneous births offer a potentially more reliable reference tool for clinical use.