Foetal cardiac assessment is a standard part of antepartum obstetric ultrasound evaluation. Heart examination, including four-chamber view and outflow tract views, should be routinely performed for all women as recommended by The International Society of Ultrasound in Obstetrics and Gynaecology (ISUOG). Although the anatomical survey of foetal heart is well-defined, current knowledge on myocardial contractility is scarce. The aim of our study was to investigate the interventricular septum (IVS) shortening in normal foetuses. Interventricular septum length and thickness were assessed by re-evaluation of 3-dimensional spatiotemporal image correlation (STIC) acquisition planes in second and third trimesters of pregnancy in otherwise structurally normal foetuses. Twenty-one foetuses were included to the study. Mean gestational age at second and third trimester investigations were 24.4 (+/- 1.6) and 31.3 (+/- 2), respectively. Systolic and diastolic IVS length and thickness were significantly correlated with the gestational age. Interventricular septum shortening and thickening indexes were not different between second and third trimesters. Foetal cardiac contractility is a subject that recently gained attention. The current study revealed that interventricular septum shortening and thickening was relatively stable during second and third trimesters of pregnancy.