Impaired fecundity is a common measure of fertility impairment and most commonly described as a physical inability to have a child. This measure encompasses both infertility (i.e. difficulty with conceiving a pregnancy) and difficulty with carrying a pregnancy to term, as with recurrent pregnancy loss. Impaired fecundity as defined in the NSFG has 3 components: nonsurgical sterility (i.e,. physically impossible to have a child), subfecundity (i.e. physically difficult but not impossible), and "long interval without conception" (i.e. 36-months infertility).
The original baseline was revised from 11.8 to 12.7 percent due to a change in the methodology. The target was adjusted from 10.8 to 11.4 percent using the original target setting method.