The use of prediction models of spontaneous pregnancy in in vitro fertilization units reveals differences between the expected results of public and private clinics in Spain.

To evaluate the applicability of prediction models (PM) of spontaneous pregnancy (SP) in a population of infertile patients from a university-affiliated private assisted reproductive technology center (Instituto Valenciano de Infertilidad) and in the reproductive medicine section of a public university hospital (La Fe), both belonging to the same city (Valencia, Spain) between January and December 2008. We calculated the probability of SP using the PM developed by Hunault et al. in our two populations, and observed an estimated probability of SP<40% or the PM applicable in approximately 97% of the studied couples, and statistical differences between pregnancy probabilities in the two settings that were mainly a result of different age, sperm quality, and referral policies, leading us to conclude that the usefulness of PMs is limited in our environment.