In utero losartan withdrawal and subsequent development of fetal inferior vena cava thrombosis

BACKGROUND: Angiotensin receptor blockers are antihypertensive medications prescribed by a wide variety of physicians, especially for patients with coexistent diabetes mellitus. Angiotensin receptor blockers, as well as angiotensin-converting enzyme inhibitors, are contraindicated in pregnancy. CASE: We describe the reversal of losartan-induced oligohydramnios at 27 weeks of gestation with subsequent development of fetal thrombosis and possible mechanism of action for this extremely rare in utero complication. CONCLUSION: This theory may help explain the fetal stillbirths in women taking this class of medications during the second and third trimester of pregnancy.