Smoking during pregnancy can lead to detrimental health effects for the baby including but not limited to increasing the risks of the baby developing respiratory problems, lowering the amount of oxygen the baby receives and it can increase the chance of miscarriages. New research reveals a smoking mother’s embryo develops slower compared to a nonsmoker.

At an in vitro fertilization (IVF) clinic, French researchers were able to observe the growth of 868 embryos. Of those 868 women, 139 of them were smokers. All eggs were fertilized and developed in the lab through IVF procedures, which gave doctors an opportunity to monitor the embryos as they developed.

Doctors were able to examine the embryos through equipment called an embryoscope, which allows scientists to watch in real time how embryos develop without disturbing them.

Through observations, doctors noticed the embryos of those women who were nonsmokers developed quicker compared to smokers. In the five-cell stage nonsmoker’s embryos developed within 49 hours whereas the smokers developed in 50 hours. In the eight-cell stage the embryos of smokers needed at least four extra hours to develop compared to those of nonsmokers.

Doctors are unsure on the reason behind why the embryos develop slower but speculate that a delay in the embryo’s development may indicate something wrong is happening. They are also uncertain if the average two hour difference has anything to do with chances of carrying the embryo to full term.

Senior embryologist and lead researcher, Dr. Thomas Freour has one piece of simple advice for smoking women, which is “if you want a baby, quit smoking.”

According to Dr. Allan Pacey, senior lecturer in andrology at the University of Sheffield stated due to the advancement of technology, they were able to pioneer this study with the use of the embryoscope.

"It's early days for this machine but we need trials like this to test its potential, we know our current methods of embryo selection are based on what looks good down the microscope to a trained eye," he said to BBC.

This study was presented at the European Society for Human Reproduction and Embryology (ESHRE) meeting in Turkey and should be considered preliminary until published in a peer-reviewed journal.