You can judge whether the amniotic fluid is ruptured in the 3rd month of pregnancy by observing whether the vagina is flowing, pH test paper test and other methods, and the common methods of judgment are as follows: 1. Vaginal fluid: If there is a water breakage in the 3rd month of pregnancy, it is usually the phenomenon of uncontrollable vaginal flow, and if it is a high level of rupture, it will appear that the underwear is always wet, and this flow of water is uncontrollable; 2. pH test paper test: If there is vaginal fluid, you can go to the hospital to do pH test paper test, using pH test paper to detect the pH of the vaginal fluid flowing out of the pregnant woman. Because the amniotic fluid is alkaline, if the pH>7, it is likely that the amniotic fluid has ruptured, and it is recommended to do ultrasound to observe the amount of amniotic fluid. But pH test paper test will have a false positive situation, such as vaginal inflammation, etc. will cause the vaginal pH test paper is alkaline; 3, vaginal infection: if the water breaks for a long time, there will be an infection, there will also be a series of symptoms such as fever, abdominal pain. At this time, abdominal pain is not eating bad stomach pain, but contraction pain, which is because the uterus is contracting. If an infection is present, further testing of the fluid in the posterior vaginal fornix can be done, and a smear can be taken to check for the presence of amniotic tooth-like crystals to further determine if the water has broken. If ruptured amniotic fluid is detected in the third month of pregnancy, it is important to go to the hospital in time for the appropriate examination.