Folic acids can also be obtained from food sources such as lentils, dried beans, peas, nuts, avocado, dark green vegetables such as broccoli, spinach, collard or turnip greens, okra, Brussels sprouts, asparagus, citrus fruit and juice.
The findings showed that children whose mothers took the supplement throughout pregnancy demonstrated higher levels of emotional intelligence and resilience.
They were more able to express their emotions, build stronger relationships and tackle stress better.
"Our study shows that there are also potential psychological benefits for the child if supplements are taken throughout the pregnancy," said Tony Cassidy, professor at Northern Ireland.
The results were presented at the Annual Conference of the British Psychological Society in Brighton.
Previous evidence has showed that folic acid supplements taken during the first three months of pregnancy can have beneficial effects on children's brain development.
Taking a prenatal vitamin with the recommended 400 micrograms (mcg) of folic acid before and during pregnancy can help prevent birth defects of your baby's brain and spinal cord.
For the study, the team asked the parents of 39 children to answer questions about their child's personality, including levels of resilience, relationships with others and how they express their emotions.
Within this group 22 mothers had taken the supplement throughout their pregnancy while the other 19 took it during the first three months only.