For many would-be mothers, pregnancy is already a long list of things you're not allowed - cigarettes, alcohol, long-haul flights, saunas, corned beef and soft cheeses, for starters.
Now fun-hating scientists are taking away driving fast over speed bumps.
"There is lots of research about the importance of movement for women during pregnancy - our latest research looked specifically at the impacts of sudden acceleration on a pregnant woman," said Hadi Mohammadi, an engineer at the University of British Columbia.
Rather than sit a bunch of pregnant women in a car and send them speeding over bumps, they looked at data from crash tests and how pregnant women in their third trimester move.
They found going over a speed bump too fast when a baby's head is pointing downwards can cause "minor injuries to the foetal brain, an abnormal foetal heart rate, abdominal pain, uterine contraction, increasing uterine activity and further complications".
Vibrations from the bump "can cause a drag on the uterus as it goes up and then down" and put "pressure on the amniotic fluid that is protecting the foetus".
The conclusion was to slow down to the very sensible speed of 25km/h.
"Obviously, there are other variables at play when a driver approaches a speed bump, but we hope our findings provide some evidence-based guidance to keep drivers and their occupants literally and figuratively safe," said Dr Mohammadi, whose ultimate goal isn't to take away fun after all but to make vehicles safer for pregnant women.
The research was published this week in the Journal of Biomechanics.