According to the study by University of Essex, women who work up to their due date are likely to have babies with a lower birth weight.
The study found that women who worked into their ninth month of pregnancy had babies on average around half a pound lighter than those who stopped work between six and eight months, the 'Daily Mail' reported.
The University of Essex research drew on data from three major studies, two in the UK and one in the US.
Previous research has shown babies with low birth weights are at higher risks of poor health and slow development, and may suffer from multiple problems later in life.
The researchers identified 1,339 children whose mothers were part of the British Household Panel Survey, conducted between 1991 and 2005.
A further sample of 17,483 women who gave birth in 2000 or 2001 was also examined and showed similar results, along with 12,166 from the National Survey of Family Growth, relating to births in the US between the early 1970s and 1995.
One of the study authors, professor Marco Francesconi said women who might need a break before, rather than after, their babies are born should be given the opportunity to do so.
"We know low birth weight is a predictor of many things that happen later, including lower chances of completing school successfully, lower wages and higher mortality," said Francesconi.
"We need to think seriously about parental leave, because as this study suggests, the possible benefits of taking leave flexibly before the birth could be quite high," Francesconi said.
The research also suggests that women work longer into their pregnancy than they did 20 years ago.
