STDs, also known as sexually transmitted infections (STIs), are typically caused by bacteria or viruses and are passed from person to person during sexual contact with the penis, vagina, anus, or mouth. The symptoms of STDs/STIs vary between individuals, depending on the cause, and many people may not experience symptoms at all.
Many STDs/STIs have significant health consequences. For instance, certain STIs can also increase the risk of getting and transmitting HIV/AIDS and alter the way the disease progresses. STIs can also cause long-term health problems, particularly in women and infants. Some of the health problems that arise from STIs include pelvic inflammatory disease, infertility, tubal or ectopic pregnancy, cervical cancer, and perinatal or congenital infections in infants.
NICHD's research also focuses on understanding sexual risk-taking behaviors that increase the likelihood of individuals contracting STIs, on developing more effective educational interventions to prevent STIs, and on defining the consequences and optimal treatments for STIs, especially in pregnant women.