For about 60 years, the prevailing wisdom in Japan, so-called "Three-Year-Old Myth," has held that children should be raised at home by their mothers until the age of three for healthy development. But new research from the Graduate School of Medicine at Tohoku University shows that raising kids at childcare in early childhood doesn't hinder their development, and might even help with their social, motor, and problem-solving skills.

Belief in the "Three-Year-Old Myth" persisted despite Japan's Ministry of Health, Labour and Welfare insisting it has no rational basis. Still, Japanese mothers often struggle with guilt and anxiety over their decision to send their children to childcare when returning to work.

In a new study, published in Scientific Reports, a research team led by Dr Keita Kanamori, a graduate student and Professor Chiharu Ota, from the Department of Development and Environmental Medicine, found that children who started childcare when they were six months old exhibited improved development by the age of three compared with children raised at home. Improvements were across five areas: communication, gross motor skills, fine motor skills, problem-solving, and personal-social skills.

They analysed data from approximately 40,000 participants in the government-administered Japan Environment and Children's Study (JECS), the large-scale birth cohort study in Japan, where child-rearing values differ from those of Western countries. The JECS, which enrolled participants between 2011 and 2014, followed 100,000 mother-child pairs across Japan to identify the impact of environmental factors on the children's health and development.

The biggest developmental gaps between these toddlers and those raised at home were in communication and personal-social skills.

The toddlers in early childcare also had better motor skills - the ability to control and coordinate their movements. The authors speculated that this may stem from more time spent playing with others.

Though these results suggest that early childcare could result in improved development, the researchers pointed out that only a small percentage of children raised at home fell below the standard developmental cutoff values. Both home- and childcare- based child rearing have a myriad of benefits, they say, and they hope their research will dispel the myth that staying home with the mother until the age of three is essential for healthy development.

"Our key message is that both childcare facilities and home-based child-rearing are viable options, and families could choose what works best for them without guilt or anxiety," says Ota.

Looking forward, the team plans to investigate how early childcare impacts children's development beyond the age of three, as well as its impact on attachment formation and emotional development.