Four months to check.

If you want to carry out four-dimensional color Doppler examination, it is best to go to the hospital for examination at about 24-28 weeks of pregnancy. At this time, the size of the fetus is more appropriate, and the amount of amniotic fluid is moderate, so you can carry out four-dimensional color Doppler examination. After four-dimensional color Doppler ultrasound examination, it can be judged whether there is any fetal malformation. Moreover, four-dimensional color Doppler ultrasound is a kind of stereoscopic imaging, which can directly judge the development of the fetus's face and limbs to see whether there is any limb deformity or other abnormal conditions. It is also possible to judge whether there is any manifestation of congenital heart disease. Through these methods, the development problems of the fetus can be directly understood. If there is any fetal malformation, it is recommended to terminate the pregnancy in time. During pregnancy, not only four-dimensional color Doppler ultrasound detection, but also NT detection, Down's child detection and other aspects of detection, this is very important.