Polyester compositions comprising: a) at least one semi-aromatic polyester resin; b) at least one reinforcing agent; c) hydroxyapatite; d) at least one epoxy component having two or more epoxy functional groups per molecule of the epoxy component; and optionally, at least one toughener, wherein the compositions exhibit the combined property of a desirable melt viscosity stability and a desirable hydrolysis resistance to articles molded from the compositions. Articles molded or extruded from these compositions especially, electric and electronic components. Methods of maintaining melt viscosity stability of a melt-mixed composition while simultaneously retaining tensile strength in the article prepared from the melt-mixed composition.