Four-dimensional sonographic assessment of fetal movement in the late first trimester

To evaluate, using four-dimensional (4D) sonography, the frequency of fetal movements during the late first trimester of normal singleton pregnancies.

Singleton pregnancies were studied-using transvaginal 4D sonography-for 10 minutes at 10-11 and 12-13 weeks of gestation. The frequencies of 5 fetal movements (isolated arm, isolated leg, short trunk, long trunk, and jumping movements) were evaluated.

In the 17 pregnancies studied, the most frequent fetal movements were isolated arm movement at 10-11 weeks and jumping movement at 12-13 weeks. There was a significant difference in the frequency of jumping movement between 10-11 and 12-13 weeks (P<0.05).

The difference in frequency of 5 fetal movements at 10-11 and 12-13 weeks of gestation may be caused by early neuromuscular development and differentiation of the neuromuscular system.