REDUCTION OF FALSE-POSITIVE DIAGNOSIS OF FETAL GROWTH RESTRICTION BY APPLICATION OF CUSTOMIZED FETAL GROWTH STANDARDS

Objective: To evaluate the clinical performance of fetal growth charts adjusted for individual maternal characteristics. Methods: The study group consisted of 267 low-risk singleton pregnancies with normal clin ical outcome. Mothers were recruited prospectively after the booking v isit, then underwent three to five ultrasound examinations for fetal w eight estimation. Individual growth curves were generated from these d ata and the birth weight, based on log-polynomial growth model. Comput er software was written to calculate the number of fetal growth curves that cross the tenth percentile limit, based on an adjusted, average ultrasound standard for out population, compared with the number that cross this limit if it is customized for known pregnancy characteristi cs such as maternal height, booking maternal height, abolition weight, parity, and ethnic group. Results: Individual growth trajectories of this group of pregnancies with normal outcome were significantly less likely to cross below the tenth percentile for fetal weight when using customized growth charts than when the unadjusted standard was used ( McNemar's test, P < .001). Conclusion: The relationship between matern al characteristics and fetal size needs to be considered in the assess ment of fetal growth. The use of a customized standard reduces the fal se-positive rate for the diagnosis of growth restriction in a normal p opulation.