Objective: To establish reference intervals for fetal lung growth.
Design: Longitudinal observational study.
Subjects: Fifty-eight women with initially uncomplicated singleton pregnancies were recruited from the antenatal population of a teaching hospital. Four women were excluded from the final analysis because of complications arising in their pregnancy.
Methods: Each subject was serially scanned at monthly intervals. At each visit lung volume was measured using an ultrasound-based computerized three-dimensional imaging system. Multilevel models were used to determine conditional and unconditional reference intervals.
Results: Reference intervals for fetal lung growth were derived. Fetal lung volume increases in a non-linear way with gestation.
Conclusions: Our computerized system has the capacity to be used in conjunction with any standard two-dimensional ultrasound scanner in order to measure volume. Lung volume measurement may be useful in predicting pulmonary hypoplasia.