Whether children will be right or left handed is determined in the womb, new research reveals.
Pregnancy scans reveal foetuses show a dominance for the right or left hand just 18 weeks into gestation, an Italian study found.
In up to 100 percent of cases, this hand dominance accurately predicts whether the baby will be right or left handed in later life, the research adds.
Previous studies suggest being left or right handed influences the development of different regions of the brain, which may determine people's risk of conditions such as depression, schizophrenia and autism.
In the future, such conditions may be preventable by determining babies' hand dominance during pregnancy, according to the researchers.
How the research was carried out
Researchers from the International School for Advanced Studies in Trieste, Italy, analysed 29 pregnant women who were between 18 and 21 weeks into their gestations.
Their babies were monitored via 20-minute ultrasound scans to determine their hand movements.
The researchers then assessed whether the same children were right or left handed nearly 10 years later.
Hand dominance appears 18 weeks into pregnancy
Results reveal babies show a dominance for their right or left hand just 18 weeks into pregnancy.
In between 89 and 100 per cent of cases, this hand dominance accurately predicts whether the child will be right or left handed in later life.
The results are particularly impressive as most children do not actively use one hand over another until they are at least toddlers.
The findings were published in the journal Scientific Reports.