Smoking during pregnancy 4D passes may also be malformed, but the chances are usually small. Smoking during pregnancy can jeopardize fetal development and may lead to fetal developmental delays or malformations, which require close and good pregnancy checkups. Four-dimensional ultrasound examination is a dynamic video examination, can observe the development and activities of the fetus in the uterine cavity, through four-dimensional ultrasound examination can be early detection of fetal body surface deformities, the development of various organs abnormalities and malformations of the cardiovascular system and other abnormalities. The four-dimensional ultrasound examination can only say that the chance of malformation is very small, but it is not absolutely accurate. Because the examination process due to the fetal position and mobility, the level of doctors and instrument resolution and other factors, may make the examination results inaccurate. So even if the four-dimensional ultrasound examination passed, but also can not completely rule out the chances of malformation, the later still need to do a good job of pregnancy checkups.