Changes in fetal cardiac axis between 8 and 15weeks' gestation

Objectives To document changes in the normal embryonic/fetal cardiac axis in the late first and early second trimesters of pregnancy. Methods Images from 188 fetal echocardiograms performed prospectively between 8 and 15weeks' gestation in 166 healthy pregnancies and in 10 pregnancies with severe fetal heart disease were reviewed. For each echocardiogram, three measurements of the cardiac axis were taken in the axial plane at the level of the four-chamber view. Differences in mean embryonic/fetal cardiac axis at different gestational ages in the healthy pregnancies were compared. Results The mean ± SD embryonic/fetal cardiac axis was 25.5±11.5° from 8+0 to 9+6weeks (Group1), 40.4±9.2° from 10+0 to 11+6weeks (Group2), 49.2±7.4° from 12+0 to 12+6weeks (Group3), 50.6±5.7° from 13+0 to 13+6weeks (Group 4) and 48.6±7.3° from 14+0 to 14+6weeks (Group 5). Groups 1 and 2 were significantly different from each other and all other groups (P