PIP: This paper examines the uterine contractility pressure and the frequency within 7 days after normal menstruation and the difference of uterine contractility pressure between women with frequent IUD expulsion and women with 1st IUD insertion. The results show the following. 1) Uterine contractility pressure was 2.21-14.14 mmHg (average value 7.66 +or 2.89 mmHg) in 23 cases within 7 days after menstruation. The uterine contraction frequency was 28-76 times in 10 minutes with an average frequency of 4.51-1.14 times/minute. 2) The uterine contractility pressure showed no marked difference between 1st IUD insertion and frequent IUD expulsion women before and after IUD insertion (P0.05). 3) The contractility pressure of IUD insertion is bigger than that without IUD. There is a marked difference in the results between the 2 groups (P0.05). 4) The uterine contractility pressure and frequency were significant (P0.05) between 1st insertion before and after taking of the IUD (both before and after). 5) In patients with frequent IUD expulsions, the uterine contractility pressure before IUD insertion is obviously different from that after insertion (P0.05) but it is identical to the 1st insertion group. When this method is used to examine the pressure over 37-62 mmHg, some women experience subabdominal pain. (author's modified)