Time-lapse photography has shown that embryos of smoking women develop more slowly.French academics in an in vitro fertilization (IVF) clinic took regular pictures of an egg from the moment it was fertilized until it was ready to be implanted into the mother. At all stages of development, embryos from smokers were consistently a couple of hours behind, a study showed. The lead researcher from Nantes University Hospital said ‘You want a baby, quit smoking!’Smoking is known to reduce the chances of having a child .It is why some hospitals ask couples to give up smoking before they are given fertility treatment.As eggs fertilized through IVF initially develop in the laboratory before being implanted, doctors had a unique opportunity to film the embryos as they divided into more and more cells. Researchers watched 868 embryos develop only 139 from smokers.In the clinic, the embryos of non-smokers reached the fire cell stage after 49 hours. In smokers, it took 50 hours. The eight-cell stage took 62 hours in smokers’ embryos, while non- smokers’ embryos reached that point after 58 hours. Senior embryologist and lead researcher, Dr Thomas Freour said, "Embryos from smoking women are slower; there is a delay in their development. On average it is about 2 hours significant.” The study uses a fancy piece of equipment called on embryo scope, which allows scientists to watch in real time how embryos develop without disturbing them.