Researchers in Sweden have also found that women who work in hairdressing salons have a slightly increased risk of having small babies, compared with the general population.
The scientists suggest that the chemicals used to style hair, including colours and hairspray, could be responsible.
They have suggested that hairdressers who are expecting a baby should always use gloves and should ensure salons are properly ventilated.
Dr Lars Rylander and colleagues at Lund University surveyed more than 7,000 hairdressers who had trained in Sweden between 1970 and 1995.
Survey
Of these, 3,706 had given birth during this time.
These women were surveyed on the health of their baby at birth and their exposure to chemicals at work. Around two-thirds replied.
Their answers were compared to those of a control group - women of similar age but working in different jobs.
The survey showed that hairdressers were 10% more likely to give birth to babies who were small for their age, compared to other women.
They were also one-third more likely to give birth to babies with major physical defects or malformations. The most common problem was heart defects.
The researchers suggested that while there was no clear link there may be an association between the increased risk and chemicals used by hairdressers.
'Wear porotection'
But they added that further studies were needed because their research did not examine whether other factors, such as long periods of standing or stress or alcohol intake, played a role.
Writing in the journal Occupational Environmental Medicine, the authors said: "The main finding of the present study was an increased risk among Swedish hairdressers of having infants being small for gestational age compared with women from the general Swedish population.
"In addition, the hairdressers' infants had a higher incidence of major malformations."
The authors said their findings highlighted the need for hairdressers to wear protective gloves when working and particularly when they are pregnant.
They added that salon owners should ensure their shops are well ventilated particularly in areas where colours are mixed.