The normal value of amniotic fluid index at 28 weeks of pregnancy is 8-25 cm. The amniotic fluid index is obtained by dividing the amniotic cavity into four quadrants from the navel and measuring the maximum depth of amniotic fluid in each quadrant and adding them together. The maximum depth of amniotic fluid is the maximum measurement of the depth of amniotic fluid in the amniotic cavity, and the normal range should be 3-8 cm. The amniotic fluid index changes markedly at different gestational weeks, and the amount of amniotic fluid gradually increases with the increase of gestational weeks after the mid-pregnancy period, reaches a peak at 32 weeks, and gradually decreases in the last 2-4 weeks. If there is too much or too little amniotic fluid, you must consult a doctor in time. Amniotic fluid abnormalities are usually divided into the following two kinds: 1, too much amniotic fluid: amniotic fluid index > 25cm, suspected fetal malformation, chromosomal abnormality, or twin pregnancies, diabetes mellitus, gestational combination of maternal and child blood group anomalies, etc., so you have to be examined one by one, and regular ultrasound to understand the size of the fetus and the amount of amniotic fluid, test blood glucose, urinalysis, etc., and to prevent infections; 2, too little amniotic fluid: amniotic fluid index <25 cm. Low amniotic fluid: amniotic fluid index <8cm, suspecting insufficient water intake, gestational hypertension, abnormal placental function, fetal congenital urethral defects. If it is caused by insufficient water intake, the amount of amniotic fluid can be increased by infusion. Pregnant women should also pay attention to large amounts of water supplementation in their daily life, and drink more soy milk or other nutritious soups.