Background and Aim: Pregnancy and exercise training are associated with changes in the cardiovascular anatomy and physiology. There is a few studies on this issue in Iran. In this regard, the aim of this study is to assess the effect of a combined exercise training program on blood pressure and heart rate variability of pregnant women.
Methods & Materials: This randomized clinical trial was conducted in Shahid Akbarabadi Hospital in Tehran, Iran in 2019. Participants were 10 healthy pregnant women with a gestational age of 24-26 weeks in the interventional group and 10 healthy pregnant women in the control group. The interventional group received 8 weeks of combined exercise training at moderate intensity. The blood pressure measurement, electrocardiogram and aerobic and resistant exercise tests of samples were performed before and after training. AST3000 Avicenna software was used to analyze the heart rate variability parameters, and for statistical analysis, paired and independent t-tests, Mann Whitney U, and Wilcoxon tests were used. 
Ethical Considerations: This study with registered clinical trial code IRCT20190227042856N1 was approved by the Research Ethics Committee of Islamic Azad University of Science and Research Branch in Tehran, Iran (code: IR.IAU.SRB.REC.1397.101).
Results: The mean systolic and diastolic blood pressure levels were lower in the interventional group by the 34th week of pregnancy compared to the control group (P<0.05). The mean of time-domain parameters in the interventional group were higher by the 34th week of pregnancy compared to the control group (P<0.05). 
Conclusion: Combined exercise training can improve autonomic and parasympathetic nervous systems in pregnant women.