Aim: a review of the available literature on the course of pregnancy, the consequences for the mother and the fetus, and the methods of treatment of pregnant women with undifferentiated connective tissue disease (UCTD). Materials and methods. Analysis of foreign publications by topic in professional journals, as well as data from Internet resources such as PubMed^® and Embase. Results. In a retrospective study on 81 patients with UCTD and 100 pregnancies, 13% flared during pregnancy or puerperium, 3% of which experienced more severe flares and developed systemic lupus erythematosus with renal impairment. In the remaining cases, cutaneous manifestations (3%), hematological abnormalities (3%), arthralgias (1%), venous thrombosis (1%), myositis (1%) and chest pain (1%), occurred. In a retrospective study by 11% of pregnancies ended in miscarriage in the first trimester and 29% experienced obstetric complications: small for gestational age infants (10%), intrahepatic cholestasis of pregnancy (3%), preterm premature rupture of the membranes (2%), gestational diabetes (2%) and pre-eclampsia (1%). In another case control study the prevalence of pregnancy complications was 39% among women with UCTD vs 13.4% among healthy women. Aspirin may improve clinical manifestations of rheumatic disease and other inflammatory disorders, but may also be used for the management of antiphospholipid syndrome and for the prevention of pre-eclampsia. Corticosteroids at low dosage may improve pregnancy outcomes in women with UCTD. In fact, hydroxychloroquine seems to increase the live birth rate in pregnant women with persistent positive antiphospholipid antibodies to reduce the incidence of fetal growth restriction and other obstetric complications such as pre-eclampsia. Several studies have showed that vitamin D deficiency is involved in several autoimmune disorders and that its supplementation may reduce disease activity. Conclusions. UCTD is the most common rheumatic disorder diagnosed in pregnant women, but data on the course of the disease, consequences for the mother and fetus, and treatment during pregnancy are very limited. During active manifestations of the disease, women are recommended to be carefully monitored during pregnancy, due to the risk of developing severe disease course and adverse pregnancy outcome. Nonsteroidal anti-inflammatory drugs, corticosteroids, antimalarial drugs can be used to reduce disease activity and pregnancy complications. Taking vitamin D and low-dose aspirin in pregnant women with concomitant autoimmune diseases prevents adverse obstetric consequences.