Seminal fluid and fertility in women
Seminal fluid constituents contacting female reproductive tissues at coitus induce an immune response that impacts fertility and pregnancy health in women.
Volume 106, Issue 3, Pages 511-519
Sarah A. Robertson, Ph.D., David J. Sharkey, Ph.D.
Seminal fluid is often viewed as simply a vehicle to carry sperm to fertilize the oocyte, but a more complex function in influencing female reproductive physiology is now evident. Remarkably, seminal fluid contains signaling agents that interact with the female reproductive tract to prime the immune response, with consequences for fertility and pregnancy outcome. Experiments in rodent models demonstrate a key role for seminal fluid in enabling robust embryo implantation and optimal placental development. In particular, seminal fluid promotes leukocyte recruitment and generation of regulatory T cells, which facilitate embryo implantation by suppressing inflammation, assisting uterine vascular adaptation, and sustaining tolerance of fetal antigens. There is emerging evidence of comparable effects in women, where seminal fluid provokes an adaptive immune response in the cervical tissues after contact at intercourse, and spermatozoa accessing the higher tract potentially affect the endometrium directly. These biological responses may have clinical significance, explaining why  intercourse in IVF ET cycles improves the likelihood of pregnancy,  inflammatory disorders of gestation are more common in women who conceive after limited sexual activity with the prospective father, and  preeclampsia incidence is elevated after use of donor oocytes or donor sperm where prior contact with conceptus alloantigens has not occurred. It will be important to define the mechanisms through which seminal fluid interacts with female reproductive tissues, to provide knowledge that may assist in preconception planning and infertility treatment.