A primigravida woman appealed to the antenatal clinic on the 22.03.03 with complaints of boring pain in the lower part of abdomen. Anamnesis registered that her last menstruation was on the 4.01.03. Bimanual examination revealed that uterine servix is intact, external fauces is closed, uterus is enlarged up to the 9-th week of pregnancy, movable, painless. What complication can be suspected?