These findings potentially also explain the very conflicting results in the literature regarding GH utilization in association with IVF, as unselected utilization will, of course, dilute effectiveness of GH treatment: Just as aspirin will relive headache only in patients with headache and will be ineffective in a general population without a preponderance for headache, so will GH only be effective in women with low IGF-1 levels, through which GH exerts its physiological effects on ovaries. Here, GH1 is linked to Headache.