Background: Uterine environment and fetal period can profoundly affect health of the neonat. Hypoxia-inducible factor-1α (HIF-1α) is a transcription factor that regulates cellular stress responses and its activity is essential in both embryogenesis and postnatal life. The aim of the present study was to investigate the effects of maternal swimming on rat pups' HIF-1α levels as a key regulator of oxygen in lungs.

Methods: Sixteen female Wistar rats weighing 180- 200 grams were acclimated to a new environment consisting of equal light-darkness cycle and ad lib access to chow and adapted to the stress caused by water for two weeks. The rats were divided into two swimming and control groups. Swimming training began on the first day of pregnancy in a pool and continued for 3 weeks (1 h/day, 5 days/wk). Pups' lungs were removed two days after birth and their HIF-1α concentration was determined with enzyme-linked immunosorbent assay (ELISA). Statistical analysis of the data was done using independent t-test. A p-value smaller than 0.05 was considered statistically significant.

Results: Swimming lead to a significant (P<0.001) increase in the pups' lung HIF-1α levels compared with the control group. Although 3-wk period of swimming training, showed no significant increase in weight and also lung weight of newborns. Thus it can be concluded that swimming endurance training in pregnancy, can be considered as appropriate alternative in order to embryos development.

Conclusion: Our research suggests that HIF-1α level is an essential element for the development of the lungs of embryos. Moreover, further studies on the lung HIF-1α levels at post-natal period with different modes of exercise will provide more clear insight into the mechanisms of the findings resulting from this study.