An adjustable fetal weight standard for twins: a statistical modeling study.

Area of Science:

• Maternal-Fetal Medicine
• Perinatology
• Fetal Growth Assessment

Background:

• Current twin fetal growth assessment relies on singleton standards, which may not be accurate.
• There is a need for a twin-specific fetal weight standard.
• The standard should be adjustable for factors like race/ethnicity.

Purpose of the Study:

• To create an adjustable fetal weight standard specifically for twins.
• To validate the standard across different race/ethnic groups.
• To compare the new standard with existing international growth curves.

Main Methods:

• Construction of a fetal weight standard using over 500,000 low-risk twin births in the US (1995-2004).
• Adaptation of Hadlock's fetal growth standard and application of the proportionality principle.
• Validation against diverse US race/ethnic groups and international datasets.

Main Results:

• Excellent agreement of the adjustable standard with observed birthweight data for non-Hispanic White, non-Hispanic Black, Hispanic, and Asian populations (24-38 weeks gestation).
• Good fit with cross-sectional data from Australia and Norway, and longitudinal data from Brazil.
• Discrepancies noted with studies from Japan and the US when gestational age was estimated by last menstrual period.

Conclusions:

• The developed adjustable fetal weight standard for twins is a versatile tool.
• It demonstrates applicability and reliability across various global populations.
• This standard offers improved accuracy for assessing twin fetal growth.