The absence of amniotic fluid at 28 weeks of pregnancy may be caused by the pregnant woman drinking less water, premature rupture of membranes, aging of the placenta, etc. The pregnant woman needs to drink more water and follow the doctor’s instructions for fluids. 1. Pregnant women drink less water: normally, the depth of amniotic fluid at 28 weeks is within 3-7 cm, less than 3 cm indicates that the amniotic fluid is too low, which may be due to the low amniotic fluid index caused by the pregnant women drinking less water, and the symptoms can be improved by drinking more water. 2. Premature rupture of membranes: In premature rupture of membranes, amniotic fluid flows out of the vagina intermittently, resulting in an increase in the amount of amniotic fluid flowing out, leading to a low amniotic fluid index, which can also be alleviated by drinking more water, and appropriate rehydration can be done as well. 3. Placenta aging: Placenta aging will lead to low amniotic fluid, you can carry out fetal heart monitoring to determine whether there is a lack of oxygen, usually drink more water to avoid amniotic fluid loss. If there is no amniotic fluid in the 28th week of pregnancy, and the situation persists without relief, you need to seek timely medical treatment to minimize the adverse effects of the disease.