Is it better to be pregnant in three dimensions or four dimensions?

4D color Doppler ultrasound should be better than 3D color Doppler ultrasound, 4D color Doppler ultrasound in time requirements, generally in pregnancy 20 weeks-28 weeks can do, the best time is 22 weeks-26 weeks, that is, pregnant about 6 months to do, mainly for large row abnormal examination. Other time if you need B-ultrasound examination, do routine B-ultrasound can be done, regularly do a good pregnancy examination, check no problem do not worry too much.