Photo/IllutrationThe Asahi Shimbun

  • Photo/Illustraion

TAKASAKI, Gunma Prefecture--Child neglect by mothers could be a behavioral trait caused by a lack of a certain hormone received when they were fetuses, a research team has found.

The team, led by Noriaki Shimokawa, a professor of neuroendocrinology at Takasaki University of Health and Welfare, concluded that mothers’ spontaneous neglectful behavior toward their own children could be clinically explained.

The research was conducted on mice, but the scientists hope their findings will lead to medicinal measures that can prevent child neglect by mothers.

Their study was published in November in the online edition of the academic journal Proceedings of the National Academy of Sciences of the United States of America.

The team used special mice with genetic traits of child neglect, but they retained the ability to reproduce and produce milk.

In the experiments, embryos from ordinary mice were transplanted to the ovum tubes of the neglectful mice, while embryos from the neglectful mice were implanted into the ordinary mice.

The female mice born from surrogate neglectful mice tended to neglect their own pups, although they were genetically normal. All pups born from surrogate ordinary mice later showed ordinary child-nurturing behavior.

The team postulated that child-neglect behavior is deeply rooted in the conditions surrounding the mother mice when they were fetuses, rather than genetic factors.

They then studied the amount of prolactin secreted in the subject mice. This pituitary hormone is known to affect maternal aspects and behavior, including development of mammary glands and breast feeding.

The scientists found that the level of prolactin was significantly low in the neglectful mice late into their pregnancy.

When extra prolactin was administered to the neglectful mice during their late pregnancy, their genetically-related pups grew up to have the same nurturing behavior as ordinary mice.

Shimokawa said he was strongly motivated by a child-neglect incident in 2010 in Osaka, in which a mother left her two children, aged 1 and 3, alone in an apartment for over a month. The children apparently starved to death.

“I decided to fully commit myself to the research after learning about the shocking case,” he said. “Now, I am hoping to see further advances in the fields of research, such as how human mothers are affected by the environment when they were fetuses, and hormonal treatment to prevent child-neglect cases.”