Background: We aimed to retrospectively review data of pregnant women with the α-fibrinogen Thr331Ala polymorphism; evaluate the relationship between this polymorphism and spontaneous abortion (SA), fetal growth restriction (FGR), and intrauterine fetal death (IUFD); and assess the effects of aspirin and/or heparin. Materials and methods: We examined the outcomes of 29 pregnancies (nine women) in women with the α-fibrinogen Thr331Ala polymorphism. Of these, 16 were untreated, whereas 13 were treated with heparin and/or aspirin. Results: The live birth rate was significantly higher in the treated group than in the nontreated group (69.2 versus 6.2%; p = .0004). In addition, the prophylactic use of a low dose of aspirin and/or heparin during early pregnancy in women with Thr331Ala may be an effective method for reducing fetal loss in these patients. Conclusions: This polymorphism interacts with pregnancy to result in poor obstetrical outcomes, but these effects can be mitigated with medical intervention. This study is the first to report outcomes of pregnancies complicated by the Thr331Ala polymorphism, which we believe may cause thrombophilia, SA, and IUFD. This study highlights the need for further research on this polymorphism in pregnancy.