Immunocontraception

In the strictest sense immunocontraception is the use of an animal's immune system to prevent it from fertilizing offspring. More generally the field of immunocontraception includes related technologies that prevent embryonic implantation.

Typically immunocontraception involves the administration of a vaccine that induces an adaptive immune response which causes an animal to become temporarily infertile. Contraceptive vaccines have been used in numerous settings for the control of wildlife populations. However, experts in the field believe that major innovations are required before immunocontraception can become a practical form of contraception for human beings.

Thus far immunocontraception has focused on mammals exclusively. There are several targets in mammalian sexual reproduction for immune inhibition. They can be organized into three categories.

Gamete production

Organisms that undergo sexual reproduction must first produce gametes, cells which have half the typical number of chromosomes of the species. Oftentimes immunity that prevents gamete production also inhibits secondary sexual characteristics and so has effects similar to castration.

Gamete function

After gametes are produced in sexual reproduction, two gametes must combine during fertilization to form a zygote, which again has the full typical number of chromosomes of the species. Methods that target gamete function prevent this fertilization from occurring and are true contraceptives.

Gamete outcome

Shortly after fertilization a zygote develops into a multicellular embryo that in turn develops into a larger organism. In placental mammals this process of gestation occurs inside the reproductive system of the mother of the embryo. Immunity that targets gamete outcome induces abortion of an embryo while it is within its mother's reproductive system.