Insights into the role of cervical mucus and vaginal pH in unexplained infertility / Sobre o papel do muco cervical e do PH vaginal na gênese da infertilidade inexplicada

Unexplained infertility diagnosis is made in the presence of a normal semen analysis when tubal patency and normal ovulatory function are established. Among several potential causes, unexplained infertility could be attributed to vaginal pH and cervical mucus abnormalities. Although the vaginal canal and the cervix generally function as effective barriers to sperm, and although the production of mucus is essential to transport them from the vagina to the uterine cavity, these factors receive little attention in the investigation of couples with unexplained infertility. A substantial reduction in sperm number occurs as they transverse the cervix. From an average of 200 to 300 million sperm deposited in the vagina, only a few hundred achieve proximity to the oocyte. Given this expected high spermatozoa loss, a slight modification in cervical mucus may rapidly transform the cervix into a "hostile" environment, which, together with changes in vaginal environment and cervix structure, may prevent natural conception and be a cause of infertility. In this review, we discuss the physiological role of the vaginal pH and cervical mucus in fertility, and describe several conditions that can render the cervical mucus hostile to sperm and therefore be implicated in the pathophysiology of unexplained infertility.

RESUMO O diagnóstico de infertilidade inexplicada baseia-se na presença de espermograma normal, constatadas também permeabilidade tubária e função ovulatória normais. Entre as várias causas potenciais de infertilidade inexplicada, a presença de muco cervical e pH vaginal anormais devem ser consideradas. Embora a produção adequada de muco cervical seja essencial para o transporte dos espermatozóides da vagina para a cavidade uterina, e tanto o canal vaginal quanto o colo do útero desempenham função importante como barreira à passagem dos espermatozóides, estes fatores recebem pouca atenção na investigação de casais com infertilidade inexplicada. Uma redução substancial do número de espermatozoides ocorre à medida que estes percorrem o trato reprodutivo feminino. Partindo de cerca de 200 a 300 milhões de espermatozoides depositados na vagina, apenas algumas centenas alcançam a proximidade do oócito. Alteracões do muco cervical podem rapidamente transformar o colo do útero num ambiente hostil, que em conjunto com alterações no ambiente vaginal e da estrutura de colo do útero, podem apresentar-se condicões impedientes para a concepção natural; desse modo, convertem-se em causa de infertilidade. Nesta revisão, discutimos o papel fisiológico do pH vaginal e do muco cervical na fertilidade, descrever várias condicões que podem tornar o muco cervical hostil aos espermatozoides e, por fim analisamos como estes fatores interferem na fisiopatologia da infertilidade inexplicada.

Gonadotropin therapy in assisted reproduction: an evolutionary perspective from biologics to biotech.

Gonadotropin therapy plays an integral role in ovarian stimulation for infertility treatments. Efforts have been made over the last century to improve gonadotropin preparations. Undoubtedly, current gonadotropins have better quality and safety profiles as well as clinical efficacy than earlier ones. A major achievement has been introducing recombinant technology in the manufacturing processes for follicle-stimulating hormone, luteinizing hormone, and human chorionic gonadotropin. Recombinant gonadotropins are purer than urine-derived gonadotropins, and incorporating vial filling by mass virtually eliminated batch-to-batch variations and enabled accurate dosing. Recombinant and fill-by-mass technologies have been the driving forces for launching of prefilled pen devices for more patient-friendly ovarian stimulation. The most recent developments include the fixed combination of follitropin alfa + lutropin alfa, long-acting FSH gonadotropin, and a new family of prefilled pen injector devices for administration of recombinant gonadotropins. The next step would be the production of orally bioactive molecules with selective follicle-stimulating hormone and luteinizing hormone activity.