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New Formulas for Calculating the Lung‐to‐Head Ratio in Healthy Fetuses Between 20 and 40 Weeks' Gestation
Author(s) -
Kehl Sven,
Eckert Sven,
Berlit Sebastian,
Tuschy Benjamin,
Sütterlin Marc,
Siemer Jörn
Publication year - 2013
Publication title -
journal of ultrasound in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 91
eISSN - 1550-9613
pISSN - 0278-4297
DOI - 10.7863/ultra.32.11.1939
Subject(s) - medicine , gestation , fetus , lung , obstetrics , fetal head , pregnancy , genetics , biology
Objectives The purpose of this study was to develop new formulas for the expected fetal lung area‐to‐head circumference ratio in normal singleton pregnancies between 20 and 40 weeks' gestation. Methods The lung‐to‐head ratio and complete fetal biometric parameters of 126 fetuses between 20 and 40 weeks' gestation were prospectively measured. The lung‐to‐head ratio was measured by 3 different methods (longest diameter, anteroposterior diameter, and tracing). Formulas for predicting right and left lung‐to‐head ratios with regard to gestational age and biometric parameters were derived by stepwise regression analysis. Results New formulas for calculating right and left lung‐to‐head ratios by each measurement method were derived. The formulas included gestational age only and no biometric parameters. Conclusions The new formulas for estimating the expected lung‐to‐head ratio by the 3 different methods in normal singleton pregnancies up to 40 weeks' gestation may help improve the prognostic power of observed‐to‐expected lung‐to‐head ratio assessment in fetuses with congenital diaphragmatic hernias.