Contraceptive Vaccines and Pregnancy Prevention

Abstract

According to WHO, 80 million pregnancies each year are unintended and 45 million undergo abortion. There remains a continuing need for effective long-term contraceptives with minimal side effects. Contraceptive Vaccines (CV) thus provides an attractive solution due to its periodic intake, high specificity, reversibility and minimal side effects. This review aims to evaluate the potential of contraceptive vaccines for pregnancy prevention based on journal articles obtained from PubMed, Elsevier Clinical Key and Google Scholar. CV works by using the body’s own immune system to target molecules which take part in the reproduction process but do not confer other pleiotropic effects other than infertility. Three main mechanisms of CV are currently studied, namely by affecting gamete production, gamete function and gamete differentiation (hCG). Of all these, hCG vaccines are of great interest as they are formed by early embryos, not the pregnant female hence providing the least side effects when inhibited. They are the first CV to pass Phase I and II trials successfully and found to remain effective as long as antibody titres stay above 50 ng/mL. Those vaccinated can also easily undergo pregnancy when titres go below 35 ng/mL. Normal reproductive functions also remain following vaccination. An immunological approach to contraception remains an innovative idea and has been proven effective in both experimental and clinical trials. If ongoing trials remain successful, CV will mark another progress in the field of mass contraception and its implementation would hopefully reduce the current prevalence of unintended pregnancies.