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Fetal breathing-related nasal fluid flow velocity in uncomplicated pregnancies
S S Badalian1, C R Chao, H E Fox
1Department of Obstetrics and Gynecology, College of Physicians and Surgeons, Columbia University, New York, NY 10032.
Objective:
Our purpose was to determine the Doppler ultrasonographic characteristics of fetal breathing-related nasal fluid flow velocity in uncomplicated pregnancies.
Study Design:
Fetal nasal flow velocity was studied in 52 uncomplicated pregnancies at gestational ages ranging from 22 to 41 weeks. The evaluation of fetal breathing-related nasal fluid flow velocity was performed with ultrasonography combined with color flow and spectral Doppler analysis.
Results:
The study revealed that the breath-to-breath interval and duration of the inspiratory phase of the fetal breathing-related nasal flow increased from 22 to 35 weeks and decreased thereafter. The breath-to-breath interval (milliseconds) at 33 to 35 weeks (1203.9 +/- 295.7 SD) was approximately twice what it was in the earliest age group (22 to 25 weeks); subsequently it decreased by approximately 25% in the term group (38 to 41 weeks). A positive correlation existed between the mean breathing-related nasal peak inspiratory flow velocity and advancing gestational age (r = 0.56, p = 0.0008), and between the inspiratory flow velocity acceleration and advancing gestational age (r = 0.53, p = 0.0076).
Conclusion:
Changes in fetal breathing activity during uncomplicated pregnancies can be determined by measurement of fetal breathing-related nasal fluid flow velocity. Our observations in uncomplicated pregnancies may be useful in future studies of these parameters in complicated pregnancies such as those at risk for pulmonary hypoplasia.