Ultrasonic examinations of 3000 pregnant women revealed congenital developmental defects in 22 (0.7%) fetuses: in 4 cases tumors of various sites were detected and in 2 cases the tumors were found in one of the twins. Pathologic and histologic examinations carried out after delivery revealed a sacrococcygeal teratoma and a retroperitoneal dermoid cyst in one fetus, a ganglioneuroma of the retroperitoneal space, located between the bladder and rectum, an intrapericardial teratoblastoma, and a cystic cervical lymphangioma. The latter three tumors were responsible for nonimmune fetal edema. In one case an abortion was induced at pregnancy term of 22 weeks. Three fetuses died after deliveries in various terms. Based on his own experience and the literature data, the author suggests recommendations on the policy of following up the pregnancy and labor in various periods of gestation with different number of fetuses with due consideration for the tumor size and the fetal state, as well as on the possible correction after birth.