French academics have used time-lapse photography to study the effects of smoking on the embryo, finding that embryos of smoking women develop more slowly.

The academics performed the tests in an IVF clinic, taking regular pictures of an egg from the moment it was fertilised until it was ready to be implanted into the mother. They found that the embryos from smokers were consistently a couple of hours behind, highlighting the effects of nicotine on unborn babies.

Smoking has long been known to have adverse effects during pregnancy. Because the eggs fertilised through IVF initially develop in the laboratory before being implanted, doctors were able to take a closer look at how smoking can affect the embryos.

They found that the embryos of non-smokers reached the five-cell stage after 49 hours, which was one hour quicker than smokers. In the eight-cell stage it took 62 hours in smokers’ embryos, while non-smokers’ embryos reached that point after 58 hours.

Senior embryologist and lead researcher, Dr Thomas Freour, told the BBC: “Embryos from smoking women, they behave slower, there is a delay in their development.

“On average it is about two hours, it is significant and nobody knew that before.”

The results do not show what impact this slower development has, it is has any at all, but Dr Freour speculated that “if they go slower, maybe something is starting to go wrong and they wouldn’t implant.”

His advice was simple: “You should quit smoking, it couldn’t be easier. What else can I say? You want a baby, quit smoking.”

The use of time-lapse photography was an interesting addition in the study, with a piece of equipment called embryoscope allowing researchers to carefully track the development of the embryos without disturbing them.

The findings were presented at the European Society for Human Reproduction and Embryology (ESHRE) meeting in Turkey.