Epidemiology of infertility and recurrent pregnancy loss in society with fewer children.

Since there has been no improvement in the current downward trend in Japan’s birth rate, the growing population of potential patients with infertility is a significant social problem. Underlying the factors of infertility are psychological factors related to the current stress of modern-day society, sexually transmitted diseases, increased smoking rates among young females, weight abnormalities such as obesity and underweight resulting from diet, an age-related decrease in reproductive function resulting from late marriage and late childbearing (social infertility), and increasing numbers of patients with polycystic ovary syndrome, endometriosis, or uterine myoma. Eighty to 90% of these factors contributing to infertility are derived from personal lifestyle and are considered to be preventable. On the other hand, 50–70% of recurrent pregnancy loss is of unknown cause, and currently there are no established standard tests or treatment policies. However, it is important to carry out close systematic investigation of the couple to determine the cause of infertility, including chromosomal or endocrine factors, blood coagulation function, uterine deformity, autoimmune diseases, and infectious diseases. Treatment specific to the cause should be provided to the patient, and the cause should be prevented if possible. It is proposed that, to prevent infertility and recurrent pregnancy loss, males and females of reproductive age undergo regular checkups of reproductive function once a year. It is expected that this kind of effort may lead to improvement of the downward trend in the birthrate.