NHK has learned that more than 420,000 in vitro fertilization procedures were conducted in Japan in 2015, a record high.
The Japan Society of Obstetrics and Gynecology gathered the data for the year from medical institutions.
There were 424,151 cases using the IVF reproductive technology, or 30,000 more than the year before.
This led to over 51,000 babies.
The results mean only 11.7 percent of women who underwent in vitro fertilization gave birth.
That's one baby born through IVF for every 20 births across the country.
Women aged 40 or older who underwent the treatment account for about 40 percent of the total.
In other countries such as Britain and France, recipients aged 40 or older account for only about 20 percent.
Professor Osamu Ishihara of Saitama Medical University says the figures show that as Japan's birthrate declines, in vitro fertilization is becoming an important means to have children. He says they also show the need to undergo infertility treatment at an early stage, and for an environment that encourages women to give birth at a younger age.