By Andrea Rodrigo BSc, MSc (embryologist).
Last Update: 03/04/2015

Stress, prolonged use of contraceptives without medical supervision and the delay of motherhood are the most important causes of infertility. However, in recent years, sexually transmitted diseases (STDs) became one of the main causes of infertility in both women and men.

The WHO estimates that about 450 million new cases of STDs are diagnosed every year, making it the most common preventable cause of female infertility.

However, although STDs are an important cause of infertility, it is generally caused by a number of different factors. These factors prevent fertilization and/or the subsequent pregnancy.

STDs that may cause infertility

About 70% of infertility cases are due to obstructions caused by viral, bacterial and fungal (yeast) STDs. These problems originate obstructions in the fallopian tubes among women and in the vas deferens among men, which prevent the egg and sperm from fusing.

Sexual intercourse with multiple partners and/or without the use of condoms favours the development of bacteria, such as chlamydia trachomatis and neisseria gonorrhoeae. These bacteria cause contagious infections, like chlamydia and gonorrhea, which may develop into a pelvic inflammatory disease.

Gonorrhea, chlamydia, and mycoplasma represent the most common infections able to damage male and female reproductive systems.

These types of infectious organisms install themselves in the cervical mucus of the cervix, decreasing sperm motility and/or altering the functionality of the fallopian tubes. In men, these agents adhere to the sperm and worsen its quality and quantity.

A man infected with chlamydia may present chronically inflamed testicles and prostate and/or alterations of the urethra and, consequently, of the seminal fluid. Infections can also cause variations in pH, thus altering the seminal fluid.

Other microorganisms that can alter fertility, and cause other serious diseases, are:

  • Syphilis
  • Herpes Simplex
  • Vaginitis
  • HIV-AIDS
  • Trichomoniasis

Sexual education

It is important to understand that, even though contraceptives prevent pregnancy, not all of them protect against STDs. The condom is one of the best guarantees of protection against, not only egg fertilization, but also the spread of STDs.

About 95% of adolescents have access to some STD preventive method, but only 5% use them. Taking this into account, it becomes essential to improve sexual and reproductive education.

It is important to explain to young people the consequences of having a STD, not only because of the problems associated with the disease itself, which can be particularly serious as in the case of AIDS, but also because of the influence STDs have on fertility.

Authors and contributors

 Andrea Rodrigo
BSc, MSc
Embryologist
Bachelor's Degree in Biotechnology from the Polytechnic University of Valencia. Master's Degree in Biotechnology of Human Assisted Reproduction from the University of Valencia along with the Valencian Infertility Institute (IVI). Postgraduate course in Medical Genetics. More information