Ultrasonographic patterns of fetal breathing movements in normal pregnancy.

OBJECTIVE

To assess through pregnancy fetal breathing movements (FBMs) patterns detected by M-mode and Doppler velocimetry technology.

METHODS

In this cross-sectional study FBMs were investigated in 1882 uncomplicated pregnancies over a 4-year period. Abdominal and thoracic wall movements of fetuses between 14 and 40 weeks of gestation were studied by M-Mode scan, and color Doppler velocimetry with spectral imaging analysis was used to investigate the presence of FBMs associated with nasal fluid flow velocity waveforms (NFFVWs).

RESULTS

Abdominal movements were observed in 19% of cases when gestation was less than 20 weeks and in 61% of cases when it was between 21 and 25 weeks; chest movements were significant after 21 weeks; and NFFVWs were detected at 22 weeks and increased progressively to 93% of cases at term.

CONCLUSIONS

Fetal breathing movements are a complex phenomenon with a composite, progressive pattern of development during gestation.