Parents of children born from donated ova are worried about telling their children the circumstances of their birth, while an increasing number of Japanese women are receiving ova donations overseas.
Although women who receive donated ova give birth to children, they are not related by blood.
These mothers also seem to think that little progress has been made in society's understanding of the situation.
Such parents are conflicted about how to explain ova donations, as there is no established support system to help them find the best way to tell their children.
Emi Kikuta, 35, a psychological counselor for reproductive affairs, has consulted with couples who want to travel overseas for ova donations.
She said, "There is no model to follow for telling these children about their birth, so many people are worried."
In autumn last year, a study was conducted in Tokyo with 10 people concerned about the issue.
Such a meeting was rare since only a small number of parents have told others about receiving ova donations.
At the meeting, a woman in her 40s who gave birth to a son from an ovum donated in South Korea said, "I'm afraid my son may come to dislike me, so I can't tell him the truth."
Among the attendees was a woman who became pregnant after receiving an ova donation in Thailand, another woman who was unable to become pregnant from an ova donation in Thailand and a couple who were considering overseas ova donations.
The woman who received an ovum in South Korea had tried to become pregnant 10 times through in vitro fertilization using her own ova.
Despite spending millions of yen in the effort, she could not become pregnant and eventually decided to try ova donations.
Kikuta said, "Though an increasing number of Japanese wish to travel overseas to receive ova donations and many children are born this way, no system has been established to help these parents explain it to their children."
In the United States, a picture book explains ova donations to children, and in many cases, parents use the book to explain the truth to their children.
The book presents methods parents can use to explain the truth in an easy-to-understand way, such as telling a child that because their mother experienced trouble having a baby, kind people decided to help her.
According to a survey by The Yomiuri Shimbun on hospitals specializing in such treatments, Japanese women gave birth to at least 130 babies from overseas ova donations in the five-year period until 2011.
Concerning overseas ova donations, in many cases, broker firms introduce donors to couples.
However, it is left to the parents' own judgment whether and how they should tell their children.
In most cases, parents are not allowed to contact donors.
The Japanese Institution for Standardizing Assisted Reproductive Technology (JISART) based in Osaka is an incorporated association comprising medical institutions that have implanted ova in women, resulting in the birth of nine children.
JISART has set up an expert panel on the issue and plans to compile a guideline on how to explain ova donations to children by the end of this fiscal year.
One condition the institution sets prior to the treatment is that parents should tell their children the truth while they are still young to prevent potentially negative consequences from finding out as an adult.
JISART's ethics committee screens couples under its own criteria for six months to a year.
The first child born from an ova donation at a member institution was in 2008, so the time to tell the child the truth is approaching.
Shiro Hirayama, 41, a psychological counselor for reproductive affairs on the JISART expert panel, said: "The children will deal with the fact they were born from an ova donation for the rest of their lives. It's important that all family members offer them support."
Suwa Maternity Clinic in Nagano Prefecture, which conducted the first provision of a third party ova donation in Japan, has helped in the births of 72 babies.
However, it has left the responsibility of informing children to their parents.
A clinic official said, "Although we have told parents they should tell their children while they are young, we can't force them to do so as there is no legal system in place."