Background: Today, ultrasonography has become the main tool used for the evaluation of fetal anomalies. The aim of this study was to evaluate fetal heart rate changes immediately after combined two- and 4-dimensional ultrasound.

Materials and Methods: This study was performed on 191 pregnant women aged 15 to 45 years old who were referred for 4-dimensional ultrasonography in summer 2013. Before the onset of 2-dimensional ultrasonography, baseline fetal heart rate was measured by ultrasound. At the same time, the maternal heart rate was recorded during one minute. Then, combined ultrasonography was performed and same parameters were recorded at the end.

Results: Maternal heart rate significantly decreased after combined ultrasonography (p=0.0001). Fetal heart rate did not differ before and after ultrasonography (p=0.693).

Conclusion: Four-dimensional ultrasonography has no effect on fetal heart as an indicator for evaluating the fetus temperature.