BACKGROUND Presence of inherited thrombophilia is an additional risk factor for maternal thromboembolism and certain adverse pregnancy outcomes, including recurrent fetal loss, placental abruption, intrauterine growth restriction and early-onset severe preeclampsia. Pregnant women with thrombophilia, especially those with antithrombin (AT) deficiency, are at high risk of both kinds of complications. METHODS We presented a pregnant women with congenital antithrombin deficiency in the first pregnancy, whose mother had had four times pregnancy-related deep vein thrombosis, and antithrombin deficiency. With the regular laboratory monitoring of hemostatic parameters and gynaecology surveillance including the follow-up of placental vascular flow, the whole pregnancy proceeded without complications. The prophylactic therapy with low molecular weight heparin was introduced from the 20th week of gestation and one dose of substitution therapy with antithrombin concentrate was administrated before delivery. Pregnancy and labour were terminated without complications at the 37th week of gestation, resulting in the delivery of a healthy male newborn of 3.6 kg body weight, 52 cm long, and with the Apgar scores of 9/10. CONCLUSIONS A timely made diagnosis of thrombophilia, accompanied with regular obstetrics check-ups and follow-ups of hemostatic parameters during pregnancy, as well as the use of adequate prophylactic and substitution therapy, are the successful tools for the prevention of possible maternal complications and pregnancy itself in our patient with congenital AT deficiency.