As proposed criteria (Swansea criteria) for the diagnosis of acute fatty liver of pregnancy (AFLP) do not include antithrombin (AT) activity, diagnosis of AFLP may be delayed. The aim of this review is to underscore problems in the differential diagnosis of AFLP and the syndrome of hemolysis, elevated liver enzymes and low platelet counts (HELLP syndrome) and to facilitate prompt diagnosis of AFLP. Published works dealing with liver dysfunction in pregnancy, HELLP syndrome and AFLP were reviewed. AFLP and HELLP syndrome shared common clinical, laboratory, histological and genetic features, and differential diagnosis between them was often difficult. However, HELLP syndrome was likely to occur in patients with hypertension, but AFLP occurred often in the absence of hypertension. In addition, AFLP was exclusively associated with pregnancy-induced antithrombin deficiency (PIATD). Approximately 50% of patients with AFLP did not have thrombocytopenia at presentation. As the Swansea criteria for AFLP did not include PIATD, diagnosis of AFLP was delayed until manifestation of life-threatening complications; 60% of women were admitted to intensive care and 15% to a specialist liver unit. In conclusion, incorporation of AT activity of less than 65% into the diagnostic criteria for AFLP may facilitate suspicion and prompt diagnosis of AFLP, decrease uncertainty regarding the diagnosis of AFLP, and contribute to better investigation and understanding of the process leading to the development of liver dysfunction.