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Published on: June 29, 2013
A fetal growth standard derived from multiple modalities
1Department of Obstetrics and Gynecology, National University Hospital, Lower Kent Ridge Rd., 119074, Singapore, Singapore. obgjmm@nus.edu.sg
Insights
This study developed a fetal weight growth standard using multiple data sources, including ultrasound and MRI. The resulting standard shows a consistent weekly gain of 5.2% of expected term birth weight.
Area of Science:
- Obstetrics and Gynecology
- Fetal Medicine
- Biostatistics
Background:
- Accurate fetal weight estimation is crucial for monitoring fetal growth and identifying potential complications.
- Existing fetal growth standards may have limitations due to reliance on specific methodologies, such as ultrasound estimations.
Purpose of the Study:
- To establish a robust fetal weight growth standard by integrating data from various sources.
- To create a more reliable reference for assessing normal fetal development across different gestational ages.
Main Methods:
- A fetal growth standard was calculated using published birth weight data, sonographic weight standards, and MRI data.
- Birth weights were adjusted for preterm infants, and all data were transformed into fractional growth curves relative to expected term weight.
- Averaging fractional curves from multiple modalities and calculating a standard deviation of 12% of the median generated the final standard, with separate curves for European and Chinese populations.
Main Results:
- The derived fetal weight growth standard demonstrates a nearly linear relationship with gestational age.
- The standard indicates a consistent weekly fetal weight gain of approximately 5.2% of the expected term birth weight.
Conclusions:
- Ultrasound-derived fetal weight curves can be influenced by biases in estimation formulas.
- A fetal growth standard developed from multiple data sources offers a more reliable assessment of normal fetal growth compared to single-modality standards.
Objective:
To create a fetal weight growth standard from published data on ultrasound-dated pregnancies.
Methods:
A fetal growth standard was calculated from published birth weight data, sonographic weight standards, and one MRI study. The birth weights from the East Midlands Obstetric Database were modified by an incremental function to compensate for the lower weights of preterm infants. Published sonographic and MRI standards, and the modified birth weight curve were transformed to yield fractional growth curves that express fetal size as a proportion of the expected term weight. These three curves were then averaged, and the standard deviation was taken as 12% of the median. Curves for Europeans and Chinese were then generated.
Results:
The average curve for fetal weight is a virtually linear function of gestational age, with a weekly weight gain of 5.2% of the expected term birth weight.
Conclusions:
Ultrasound-derived fetal growth curves are subject to bias inherent in weight estimation formulae. A standard derived from multiple modalities is likely to be a more robust estimate of normal fetal growth.
