This study set out to look at the efficacy of using thyme - celery mixture (TCM) supplementation in mitigating stress and improving the performance and behavior of pregnant ewes housed under two different conditions. Forty (40) pregnant ewes were randomly distributed into four groups; two groups were housed in the semi-shaded house (SS), including one group that was provided with TCM supplemented in diet (SST), and the other received no supplementation (SSNT). Similar to the first two groups were housed in a fully shaded house (FS), including one group that was provided with the same TCM supplementation (FST) and the other that received no supplementation (FSNT). Ewe's performance including weekly feed intake was monitored during the late stage of pregnancy, stress indicators were measured in blood. Besides, feeding behavior was recorded. As a result full shaded houses succeed to protect pregnant ewes from environmental changes despite the decreased feed intake. TCM supplementation didn’t achieve success in mitigating the physiological stress of pregnancy in both housing conditions but resulted in a significant increase in the feed intake of semi-shaded housed ewes.