Comparison of Computerized Cardiotocography Parameters between Male and Female Fetuses

Fetal sex has been identified as an important factor influencing pregnancy outcomes, but its impact on fetal heart rate (FHR) variability in uncomplicated pregnancies is still unclear. The objective of the study was to assess short-term variability (STV) and other computerized cardiotocography (cCTG) parameters in relation to fetal sex during fetal antepartum surveillance. We retrospective compared cCTG parameters of male and female fetuses in uncomplicated singleton pregnancies at term. In addition to univariate analysis, a multivariate analysis was performed taking into account maternal characteristics. A total of 689 cCTG recordings were analyzed: 335 from male fetuses and 354 from female fetuses. Analysis of cCTG results by fetal sex showed no significant difference in percentage of signal loss, number of contractions, movements, accelerations and decelerations, long-term variability (LTV), and STV at both uni-and multivariate analysis. There was a statistically significant difference for baseline FHR at the univariate analysis, which was not confirmed by a multivariate analysis. Our results suggest that fetal sex did not affect cCTG parameters in uncomplicated term singleton pregnancies, and therefore it does not need to be taken into account when interpreting cCTG in physiological conditions.