What Impact Does Male Smoking Have on Sperm and Fertility?

How His Smoking Can Hurt Both His and Her Fertility

Couple sitting on a bench while male smoking nearby
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Can smoking hurt your sperm? Yes. It can also negatively affect your fertility. You already know that smoking is bad for your health, and you have likely guessed that smoking is bad for female fertility. In both men and women, smoking has been linked to an increased risk for many cancers, heart disease, emphysema, and a number of other health problems.

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.

But that’s not the only way smoking may harm fertility. Male smoking is also associated with decreased IVF success rates and possibly increased miscarriage rates. Also, secondhand smoke can harm her fertility as well.

When he smokes, it not only decreases his sperm health. It also decreases her fertility.

How Does Smoking Effect 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 percent decrease in sperm concentration in men who smoke.

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 percent decrease in sperm motility.

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 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.

But 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.

Paternal Smoking and the Fertility of Your Children

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 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.  

What About Smoking Harms Male Fertility?

Toxins found in cigarettes are frequently to blame for bad health effects, but that 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. 

Secondary Effect on Female Fertility When the Man Smokes

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 percent.

If you are going to smoke, be sure to do so away from your partner, so not to negatively affect her fertility.

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.

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 percent. For the women whose partners didn’t smoke, the pregnancy success rate was 38 percent.

If you're going through fertility treatment, it's well worth quitting smoking to improve your chances of success.

How Long After You Quit Smoking Will Your Sperm Improve?

There are no specific studies looking at this. However, we do know that it takes almost three months for sperm cells to reach maturity.

Therefore, allowing at least three months for improvement after kicking the habit makes sense.

Sources:

Jenkins TG1, James ER1, Alonso DF2, Hoidal JR3, Murphy PJ4, Hotaling JM1, Cairns BR4,5, Carrell DT1,6, Aston KI1. “Cigarette smoking significantly alters sperm DNA methylation patterns.” Andrology. 2017 Sep 26. doi: 10.1111/andr.12416. [Epub ahead of print]

Olek, Michael J., Gibbons, William E. "Optimizing natural fertility in couples planning pregnancy." UpToDate.

Nizard J1. [What Are the Epidemiological Data on Maternal and Paternal Smoking?]. J Gynecol Obstet Biol Reprod (Paris). 2005 Apr;34 Spec No 1:3S347-52. [Article in French]

Sharma R1, Harlev A2, Agarwal A3, Esteves SC4. “Cigarette Smoking and Semen Quality: A New Meta-analysis Examining the Effect of the 2010 World Health Organization Laboratory Methods for the Examination of Human Semen.Eur Urol. 2016 Apr 21. pii: S0302-2838(16)30069-0. doi: 10.1016/j.eururo.2016.04.010. [Epub ahead of print]

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