The toxins in cigarettes take their toll not only on the lungs but also on the health of your entire body. This includes your reproductive system. In April of 2016, European Urology published a meta-analysis on the effect of smoking on semen health. The analysis included 20 studies and just over 5,000 men across Europe. The study found that smoking was associated with decreased sperm count, decreased sperm motility (that’s how sperm swim), and poor sperm morphology (how sperm are shaped.) Most notably, the negative effect smoking had on sperm health was stronger in infertile men and in moderate to heavy smokers, compared to light smokers.
Impact of Smoking on Sperm and Semen Quality
Studies on male smoking have shown a decrease in the quality of semen. How does smoking affect sperm? Men who smoke have decreased sperm concentration, decreased motility (how sperm swim), fewer normally shaped sperm, and increased sperm DNA damage. Here’s a closer look:
Sperm concentration: Sperm concentration refers to the number of sperm found in a measured quantity of semen. Studies have shown a 23% decrease in sperm concentration in men who smoke.Sperm DNA: Some studies have found that the sperm of smokers has increased DNA fragmentation. DNA damaged sperm may lead to problems with fertilization, embryo development, embryo implantation, and increased miscarriage rates. Male smokers may also have abnormal hormone levels, which can affect fertility.Sperm morphology: Sperm morphology refers to the shape of sperm. Oddly shaped sperm may not swim well enough to get to the egg and may not be able to fertilize an egg. Male smokers have fewer healthy shaped sperm than non-smokers.Sperm motility: Sperm motility refers to the swimming capabilities of the sperm. If sperm cannot swim properly, they may have trouble reaching the egg and fertilizing it. In men who smoke, researchers found a 13% decrease in sperm motility.
Does Male Smoking Cause Male Infertility?
These decreases in sperm health and abnormal hormone levels may not be enough to cause infertility in men. At least, not in isolation. Reduced semen health doesn’t always mean infertility. Studies connecting smoking directly to pregnancy rates and male infertility are contradictory or unclear. For men who are already on the borderline of infertility, smoking may be enough to push them over the edge into infertility. If your semen analysis results come back on the border of infertility, quitting smoking may improve your fertility enough to not need additional fertility treatment. At the very least, dropping the habit may improve your chances of fertility treatment success. Luckily, sperm does improve after you quit smoking. While there’s no consensus on how long this will take, we do know that it takes almost 3 months for sperm cells to reach maturity. Therefore, allowing at least 3 months for improvement after kicking the habit makes sense.
How Does Smoking Hinder Male Fertility?
Toxins found in cigarettes are frequently to blame for bad health effects. Smoking exposes men to high levels of cadmium and lead, metals that have been linked to decreased fertility. Lead levels have been found to be significantly higher in infertile smokers when compared to both fertile and infertile non-smokers. Heavy smokers (those who smoke 20 or more cigarettes per day) were found to have higher levels of cadmium in their semen. But these toxins may not be the only factor. Zinc levels may play a role. One study found that male smokers who had lower zinc levels in their semen also had poor sperm concentration, movement, and shape. On the other hand, in smokers who had normal semen zinc levels, there were still issues with sperm concentration, motility, and morphology, but the degree of abnormality was less.
Paternal Smoking and Fertility of Offspring
Researchers also looked into the possible effects of paternal smoking. In other words, if the male partner smokes, will his smoking lead to infertility for his future child? The findings did not show a connection between decreased fertility in the child if the father smokes. (By the way, when the mother smokes, research has found that it increases the risk her son will face infertility.) This doesn’t mean that a father’s smoking doesn’t affect the health of the child in other ways. Researchers did find an increased risk of birth defects in the children of male smokers, as well as an increased risk of cancer. This may be related to damage to sperm DNA. One study looked at the sperm DNA of smokers and non-smokers. They found that sperm from smokers had DNA alterations, and while it’s not yet known exactly how that may affect any future children, theoretically it could explain the increased risk of birth defects found in the offspring of male smokers.
Secondary Effect on Female Fertility
Another factor to consider is the effect male smoking has on the female partner. Studies have shown a possible decrease in female fertility when women are exposed to secondhand smoking. One study found that secondhand smoke (or passive smoking) reduced the number of eggs retrieved in an IVF cycle by 46%.
Smoking and IVF-ICSI Success
Researchers also looked at the effect of male smoking on the success rate of IVF with ICSI treatment. ICSI treatment involves taking a single sperm and guiding it directly into the egg, in hopes it will lead to fertilization. It’s often used in cases of moderate to severe male infertility, or when previous IVF treatments have failed for unknown reasons. ICSI is also used for those doing IVF with pre-implantation genetic testing of the embryos (PGT). The researchers found that male smoking had a significant effect on the success rates of IVF-ICSI treatment. In one small study on IVF-ICSI, the clinical pregnancy rate in women whose partners smoked was 22%. For the women whose partners didn’t smoke, the pregnancy success rate was 38%. If you’re going through fertility treatment, it’s well worth quitting smoking to improve your chances of success.
What About Chewing Tobacco?
Generally speaking, smoking is more harmful to your overall health than chewing tobacco. However, chewing tobacco is far from harmless. Your risks of oral cancers, respiratory cancers, and cardiovascular disease are higher. Does chewing tobacco harm fertility? Possibly. Studies have found that heavy chewing can negatively impact sperm concentration, motility, shape, and viability. Whether it’s enough to decrease fertility isn’t clear.
Erectile Dysfunction and Smoking
Smoking is strongly correlated with an increased risk of erectile dysfunction, with some studies showing a three-fold increase in risk for male smokers. The more a man smokes, the more likely it is that he’ll suffer from erectile dysfunction. Erectile dysfunction isn’t the same as infertility. However, if sexual performance is difficult, getting pregnant isn’t going to be easy. The good news is that quitting smoking does seem to improve performance. One study found that after 6 months of smoking cessation, a little more than 50% reported improved sexual performance.
