1.Before the examination, you need to prepare the blood routine, blood type, virus four, blood coagulation analysis, electrocardiogram, recent fetal ultrasound single and a copy of ID card; 2.Amniotic fluid examination day you can eat, drink water, pay attention to rest, ten minutes before the operation need to empty the urine; 3.Amniotic fluid examination of the optimal time: 19 – 26 weeks of gestation, the Center can be extended to the 28th week of gestation; 4.Amniotic fluid examination needs to be rested in the hospital for 2 hours after going back to the Do not engage in physical labor, the puncture site can not be wet water for 3 days.