Clary Sage - what is it and what does it do? The reason that’s often given for clary sage bringing on labour is that it increases your levels of the hormone oxytocin – which is a hormone that, at the right levels, stimulates your uterine muscles to contract and also increases the production of prostaglandins that increase contractions further. Using clary sage during menopause, labour and in postpartum may help ease stress and pain levels