Can Smoking During Pregnancy Cause a Miscarriage?

Find Out Just How Dangerous Cigarette Smoking Can Be

Pregnant Woman Smoking


Can Smoking During Pregnancy Cause Miscarriage and Stillbirth?


Smoking—especially during pregnancy—is a risky move. For years, doctors have known that women who smoke while pregnant have almost double the risk of having a low-birthweight baby and an increased risk of giving birth prematurely. Even exposure to secondhand smoke carries risks. Cigarette smoke can cause numerous health problems in children that last for years after birth.

There's possibly even a link to an increased risk of childhood leukemia.

If that’s not enough to motivate pregnant women to avoid cigarette smoking, the evidence is mounting that exposure to secondhand cigarette smoke in pregnancy—even in mothers who don’t smoke—also increases the risk of miscarriage and stillbirth. Some evidence even indicates that heavy smoking by the father (more than 20 cigarettes a day), possibly even before conception, may also increase the risk of miscarriages.

How Could Smoking Cause a Miscarriage?

Smoking could cause a miscarriage in a number of ways. In the early days of pregnancy, when the fetus develops so quickly, cigarette smoke may cause genetic damage in the baby. Chromosomal problems are the most common cause of miscarriages, so it’s possible that heavy exposure to cigarette smoke could be a trigger. Smoking could also change the lining of the uterus (also known as the womb) to make it harder for the fertilized egg to implant.

If you are wondering how the father’s smoking could increase the risk of miscarriages, the answer may lie in the sperm. A few studies have found that men who smoke heavily tend to have increased incidence of sperm with chromosomal abnormalities, and, again, a chromosomal abnormality in the developing baby is the most common cause of miscarriages.

It may also be that the father's smoking causes the mother to be around secondhand smoke, which could cause problems in the mother's ability to maintain the pregnancy. Future studies will hopefully reveal the exact mechanism behind this link.

Other studies have found an even stronger link between smoking and miscarriages when looking at only miscarriages in which the baby had normal chromosomes. So the reason why smoking increases miscarriage risk may have nothing to do with chromosomal problems and could have more to do with something else, such as the placenta having a diminished capacity to transport oxygen and nutrients to the fetus. Research indicates that later in pregnancy, smoking does appear to decrease the placenta’s ability to deliver nutrients to the developing baby. In addition to potentially causing miscarriages, this can cause babies to be born with lower birth weight and can also increase the risk of stillbirth, as well as death in the first year of life.

Studies don't agree on exactly how much smoking increases your risk of miscarriage, but regardless, quitting smoking or avoiding cigarette smoke is one of the few miscarriage risk factors that you can control. If you smoke and have had a past miscarriage, it is impossible to say whether smoking caused your miscarriage or whether it will cause a future miscarriage or stillbirth, but quitting will definitely help lower your risk for those types of pregnancy losses.

(Not to mention, it'll help you improve your own health by lowering your risk for various diseases, such as lung cancer, heart disease, and stroke.)

Of course, quitting smoking is no easy undertaking. For help, read about smoking cessation.


George, Lena, Fredrik Granath, Anna L.V. Johansson, Goran Anneren, and Sven Cnattingius, "Environmental Tobacco Smoke and Risk of Spontaneous Abortion." Epidemiology 17(2006): 500-505. 

Groch, Judity. "Heavy Smoking Compromises Uterine Receptiveness." MedPageToday. 9 Nov 2006.

March of Dimes, "Smoking During Pregnancy." Quick Reference: Fact Sheets. Nov 2004. March of Dimes. 7 Nov 2007.

Venners, Scott A., Xiaobin Wang, Changzhong Chen, Lihua Wang, Dafang Chen, Wenwei Guang, Aiqun Huang, Louise Ryan, John O’Connor, Bill Lasley, James Overstreet, Allen Wilcox, and Xiping Xu. “Paternal Smoking and Pregnancy Loss: A Prospective Study Using a Biomarker of Pregnancy.” American Journal of Epidemiology 159(2004) 993-1001. Accessed 07 Nov 2007.

Wisborg, Kirsten, Ulrik Kesmodel, Tine Brink Henriksen, Sjurdur Frodi Olsen, and Niels Jorgen Secher. "Exposure to Tobacco Smoke in Utero and the Risk of Stillbirth and Death in the First Year of Life." American Journal of Epidemiology 15 Aug 2001 322-327.