In animal studies, growth hormone has been shown to be important in early antral follicle recruitment, subsequent follicular growth, and oocyte maturation. Together with insulin-like growth factor-1 (IGF-1), growth hormone is essential early on in the recruitment of primordial follicles in the growing pool (Slot et al 2006, Wandji et al 1992, Donadeu & Peterson 2008, Scaramuzi et al 2006, Liu et al, 1998).