The morphologic estimation of the state of the sear on uterus after cesarean section is given and the risk factors of its incompetence in repeated pregnancy and labor are revealed. It is shown that postoperative pyoseptic complications in early postoperative period and medical abortions within the first year after cesarean section have a significant negative effect on the formation of incompetent sear on uterus. Threat of abor-tion in not a sign of sear incompetence on uterus and requires careful differential diagnosis. The favourable predict or of the labor by natural maternal passages is the thicknes of low uterus segment in sear area in maturity of pregnancy from 5 to 7 mm.