Some of the women ate chocolate everyday during their pregnancy
Scientists in Finland say eating chocolate during pregnancy may make for happier, livelier babies.
They questioned 300 women before and after they gave birth. They found those who ate chocolate daily were more likely to say they had happy babies.
According to a report in New Scientist magazine, the scientists believe mood-altering chemicals in chocolate may be responsible.
Katri Raikkonen and colleagues at the University of Helsinki questioned each of the women while they were pregnant.
The women were asked to rate their stress levels and the amount of chocolate they ate.
British Dietetic Association
The scientists found that women who regularly ate chocolate while they were pregnant were more likely to say their babies smiled and laughed a lot. They were also more likely to say they were active.
The scientists also found apparent differences between the babies of stressed women who ate chocolate and stressed women who didn't.
Stressed women who ate chocolate were more likely to say their babies were less fearful in new situations.
Stressed women who didn't eat chocolate said their babies were quite fearful in new situations.
The scientists said that while they could not rule out other factors, they speculated that the results could be linked to chocolate consumption.
They said chemicals in chocolate could be passed from mothers to babies in the womb.
But chocolate manufacturer Cadbury's played down the findings.
"The chemical in chocolate that is said to boost people's mood is phenylethylamine," a spokesman told BBC News Online.
"However, it is found in much smaller quantities in chocolate compared to other foods like tomatoes and fruit.
"We think the mood altering effects of chocolate are more to do with psychology rather than chemicals.
"When chocolate melts in the mouth, it has a soothing, pleasurable quality and people feel happy about it."
Nigel Denby of the British Dietetic Association was also sceptical.
"While chocolate can stimulate the release of serotonin, the happy hormone, it is unlikely that this will cross the placenta and affect the baby," he told BBC News Online.
He warned mums-to-be against over-indulging in chocolate.
"Women should only increase their weight in line with normal recommendations when they are pregnant.
"Chocolate is very high in calories and eating too much could lead to unsatisfactory weight gain.
"I wouldn't advocate supplementing the diet during pregnancy with chocolate."