['To examine the prevalence, etiology, risk factors, and outcomes of liver abnormality in pregnancy, in a tertiary medical center, and to study the potential impact of artificial reproduction techniques (ART) on the incidence and the outcome of pregnancy-related liver abnormality.', "A retrospective case-control study using an electronic database and patients' files.", 'Tertiary referral center.', 'Women in the third trimester of pregnancy who were hospitalized for delivery.', 'None.', 'Development of significant elevation of alanine aminotransferase (ALT ≥ 100 IU/L). Secondary outcomes included development of maternal and fetal complications.', 'The upper limit of normal of ALT was ≥ 1.5 times and it occurred in 440 (1.6%) pregnancies; of those, 228 (0.8%) had ALT ≥ 100 IU/L. The etiology of significant liver test abnormality was idiopathic in 47% of patients. Compared with spontaneous pregnancies (295/23,793), ART was significantly associated with liver test abnormality (145/4, 520). The presence of ALT ≥ 100 IU/L in the third trimester was associated with higher rates of cesarean sections, prematurity, low birthweight, and fetal complications.'] Is idiopathic liver function test abnormality in pregnancy associated with assisted reproduction techniques?