Comparison of low- and high-altitude Doppler velocimetry in the peripheraland central circulations of normal fetuses

OBJECTIVE: Our aim was to test the hypothesis that Doppler velocimetry of t he peripheral and central circulations in normal fetuses is not affected by moderately high altitude (Denver, Colo-1609 m) compared with sea level (Mi lan, Italy-40 m). STUDY DESIGN: One hundred nineteen patients with singleton pregnancies unde rwent Doppler waveform analysis of the following: umbilical artery, uterine artery, middle cerebral artery, ductus venosus, and the tricuspid and mitr al valves. RESULTS: Birth weights were reduced at Denver's altitude (P < .001). The ea rly/late diastolic inflow ratios of the atrioventricular valves increased w ith gestational age (P < .01), whereas systolic/diastolic ratios of the ute rine and umbilical arteries decreased with gestational age (P < .01). There were no Doppler velocimetry differences in any vessel between Denver's and Milan's altitudes. CONCLUSIONS: Gestational age has the same effect on Doppler index at both h igh and low altitudes. Moderately high altitude does not affect uteroplacen tal or fetal vascular Doppler index and may reflect normal acclimatization in the smaller Denver fetuses.