Four-dimensional is also known as four-dimensional ultrasound, do four-dimensional ultrasound amniotic fluid index between 5~25cm is normal. After pregnancy usually in 22~28 weeks to the hospital to do four-dimensional ultrasound examination, four-dimensional ultrasound examination amniotic fluid index between 5~25cm is normal, amniotic fluid index less than 5cm for amniotic fluid is too little, amniotic fluid index is greater than 25cm for amniotic fluid is too much. Too little amniotic fluid or too much amniotic fluid during pregnancy, not within the normal range may be unfavorable to the growth and development of the fetus, through the four-dimensional ultrasound examination of the amniotic fluid index is abnormal, to go to further understanding of the causes and then deal with. 1. Low amniotic fluid index may be caused by fetal urinary tract abnormalities, gestational hypertension and other reasons, usually increase the amount of water, check the serious malformation problem consider termination of pregnancy, gestational hypertension with nifedipine to lower blood pressure. 2. excessive amniotic fluid index may be multiple births, neurological or digestive malformations, gestational diabetes and other reasons, multiple births generally do not need special treatment, serious malformations consider termination of pregnancy, gestational diabetes through diet, exercise, insulin to control. After pregnancy to do a good job of maternity examination, through the four-dimensional examination of abnormalities to further judgment, and then targeted treatment, the above drugs used in accordance with medical advice.