-LSB-...] believe that it is a reliable method for an individual mother, there is no question that it delays return of fertility within a large population. (amotherinisrael.com)
In some cases, breastfeeding leads to a delayed return of fertility, and acts as a form of natural birth control for mothers. (parentingsquad.com)
Linear regression describing data on return of fertility among female cats treated with the GnRH vaccine GonaConTM. (journals.plos.org)