Smoking whilst pregnant is never under any circumstance okay. It is very harmful to both mother and child and can cause a lifetime of issues. Live Science reported a study where researchers found a link to smoking and changes in a fetus' DNA.These changes have yet to be the found as the cause of certain medical conditions found in children of smoking mothers. Some of these conditions are low-birth weight, cleft lip and palate, and asthma. After years of knowledge of the effects smoking can have on a fetus, 12% of pregnant women still continue to smoke!
The study was conducted on 7,000 newborns. They looked for epigenetic changes in the child's DNA sequence. These changes determine whether a certain gene is turned on or off. The data showed over 6,000 different places where the DNA was different than that of babies born to non-smokers. Although the babies themselves are not smoking, all the damage is still passed through the placenta. The researchers are still looking at these changes and how they can cause the birth defects the babies are be born with.
I find this study particularly interesting because my father was born with a cleft lip and palate and I know the lasting damage it can have on a person even when surgically fixed. If there are ways of preventing this from happening to other babies, I don't understand why women don't do their part in helping their children.