Khalef AT. Early In Pregnancy, Serum Activin-A Levels Can Be Used To Differentiate Between An Ectopic Pregnancy And A Normal Intrauterine Pregnancy. Adolescência e Saúde [Internet]. 2026 Aug. 17 [cited 2026 Aug. 23];21(6s):634-9. Available from: https://adolescenciaesaude.com/index.php/aes/article/view/1666