Early In Pregnancy, Serum Activin-A Levels Can Be Used To Differentiate Between An Ectopic Pregnancy And A Normal Intrauterine Pregnancy

Abstract

Background:  Ectopic pregnancy (EP) is one of the most serious complications of early pregnancy and remains a leading cause of maternal morbidity and mortality during the first trimester. Activin-A, a placental glycoprotein involved in trophoblast differentiation, implantation, and placental development, has emerged as a promising biomarker for improving the early diagnosis of ectopic pregnancy.

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Aim: This study aimed to evaluate the diagnostic utility of serum Activin-A levels in distinguishing ectopic pregnancy from normal intrauterine pregnancy during early gestation.

Patients and Methods: A hospital-based case–control study was conducted at the Department of Obstetrics and Gynecology, Tikrit Teaching Hospital, Tikrit, Iraq, from 1 October 2025 to 30 June 2026. The study included 100 pregnant women during the first trimester of pregnancy, comprising 50 women with confirmed ectopic pregnancy (cases) and 50 women with viable intrauterine pregnancy (controls). serum Activin-A concentrations were determined using a commercially available sandwich ELISA kit and correlation analysis were performed to evaluate the diagnostic performance of serum Activin-A.

Results: Serum β-hCG concentrations were significantly lower in the ectopic pregnancy group than in controls (2345.6 ± 1248.3 vs. 11892.4 ± 3562.8 mIU/mL, P < 0.001). Likewise, serum Activin-A concentrations were markedly reduced among women with ectopic pregnancy (228.47 ± 54.18 vs. 497.63 ± 91.44 pg/mL, P < 0.001). A significant positive correlation was observed between serum Activin-A and β-hCG concentrations (r = 0.684, P < 0.001).

Conclusions: Women with ectopic pregnancy exhibited significantly lower serum Activin-A and β-hCG concentrations than women with viable intrauterine pregnancy. Serum Activin-A demonstrated excellent diagnostic performance and showed superior accuracy compared with β-hCG alone. Combining serum Activin-A with β-hCG further improved diagnostic accuracy, suggesting that Activin-A may serve as a valuable adjunctive biomarker for the early diagnosis of ectopic pregnancy and may contribute to earlier intervention, improved clinical decision-making, and better maternal outcomes.