Aim of the research: The objective of the study was to design a new, physiologically relevant model for testing the biomechanical properties of fetal membranes. Furthermore, the study examined whether the anthropometric properties of mothers and infants inluence the biomechanical properties of fetal membranes. Study design: The study was organized as a randomized controlled trial with two study groups. Materials and methods: The study was conducted on 60 samples of fetal membranes (30 vaginally delivered and 30 delivered by elective caesarian section). Anthropometric data of both mothers and newborns were taken. The test was performed on two devices – a biaxial and a uniaxial testing device. Both devices were newly designed and constructed in cooperation with the Faculty of Mechanical Engineering in Slavonski Brod. Two tests were performed using the biaxial testing device. The first of the tests comprised examining the linear pressure rise up to the membrane rupture point (standard test), whereas the second one cyclically alternated pressure on fetal membranes, simulating uterine contractions. With uniaxial testing device, the samples were stretched at a steady rate of 25.4 mm/min until rupture. A statistical analysis was performed using SPSS Statistics (version 15.0, SPSS Inc., Chicago, IL, SAD). Two-sided p < 0.05 was considered significant. Results: Burst pressures were significantly higher during cyclic biaxial test both in placental (83.8 mmHg vs 69.3 mmHg, p < 0.001) and cervical region (67.9 mmHg vs 58.1 mmHg, p = 0.013). When compared by delivery type, cyclic burst pressures were significantly higher than classic burst pressures both in caesarian sections (80.6 mmHg vs 59.1 mmHg, p < 0.001) and vaginally delivered samples (73.5 mmHg vs 65.9 mmHg, p = 0.017). Moderate positive correlations were found between sample displacement during standard biaxial test and gestation, maternal BMI at birth and uniaxial force-to-rupture and maternal weight gain and sample tensile strength. Conclusion: Cyclic biaxial test is closer to physiological intrauterine conditions and tests viscoelastic properties of fetal membranes better than standard biaxial test. Burst pressures are significantly higher in the cyclic biaxial test. Moderate positive correlation was found between maternal BMI at birth and uniaxial force-to-rupture, maternal weight gain and sample tensile strength and sample displacement during standard biaxial test and gestation.