Endometriosis is a significant problem in modern medicine. The prevalence of endometriosis is 10%, it occurs in 38% of women with infertility. For a century, it was believed that pregnancy contributes to the reduction in volume and even the disappearance of foci of endometriosis. Also, the state of «pseudopregnancy» under the influence of combined oral contraceptives was once considered an effective treatment strategy. To date, it is known that decidualization of endometrioid heterotopias not only contributes to their increase in size, but can also provoke bleeding. These changes can mimic ovarian cancer on ultrasonography. Typical complications of endometriosis are enlargement, rupture, or abscess formation.It has been proven that women with endometriosis have an increased relative risk of developing: preeclampsia by 19%; fetal growth retardation by 12%; premature birth by 46%; placenta previa almost threefold; preterm placental abruption by 40%; caesarean section operations by 49%; stillbirth by 27%; postpartum hemorrhage by 5%; spontaneous intra-abdominal bleeding by 24.6 times – only two cases are known in women with endometriosis and no bleeding from the intact peritoneum is known; spontaneous bowel perforation (only 18 cases are known). It has been proven that in pregnant women with endometriosis, the invasion of the extravillous trophoblast into the spiral vessels of the uterus is impaired. However, there is evidence that the endometrioid phenotype is not associated with placental dysfunction and does not increase the risk of developing great obstetric syndromes.Since most of the complications of endometriosis during pregnancy cannot be predicted, any additional interventions are not of use. So, to date, there is no evidence of the need to introduce separate protocols for the management of women with endometriosis during pregnancy. However, there should be an individualization of the approach in each separate case. The given atypical clinical case in a woman with diffuse adenomyosis demonstrates the importance of the problem of predicting various complications of pregnancy and childbirth. Moreover, clinical cases contribute to the continuation of the study of this disease.