Smoking leads to a whole host of medical problems, from the obvious ones like cancer, emphysema, and heart disease to the lesser-known conditions, like impotence, hormonal imbalances, and dramatically decreased sperm quality.
Your smoking habit could be leading to an inability to rise to the occasion. That's right-smoking can lead to erectile complications. When you smoke a cigarette, the primary ingredients, nicotine, carbon monoxide and other toxic substances, are absorbed from the lungs into the blood stream. These nasty toxins damage your blood vessels and cause them to constrict, raising your blood pressure. In addition to constricting your blood vessels, smoking raises your cholesterol, leading to fatty deposits lining the blood vessels and obstructing blood flow. The key to a strong, long-lasting erection is healthy blood flow to the penis, as well as the ability of the blood vessels in the penis to expand and contract. Smoking, especially heavy smoking, damages your body's ability to do both of these things, potentially leading to impaired erectile performance, erectile dysfunction, and, in severe cases, impotence.
Some studies have found that nicotine exposure is linked to increased levels of cortisol, a stress hormone which in excess can break down testosterone molecules. Studies are fairly split about exactly what happens directly to your testosterone when you smoke - some have found that smoking causes a temporary increase in testosterone, while others have found that testosterone levels decrease over time. While a slight increase in testosterone may not sound all that bad, the health problems associated with smoking far outweigh a small, temporary boost in testosterone.
Where smoking really impacts your fertility is your sperm quality. Smoking affects almost every aspect of your sperm: count, motility, morphology, and semen volume.
Sperm Count: The sperm counts of smokers are generally 13-17% lower than their non-smoking brethren. This could be due to the hormonal changes we've already discussed impacting sperm production, or due to the fact that smoking increases generation of Reactive Oxygenated Species (ROS). ROS is essentially waste leftover by sperm, and in high amounts it can kill sperm.
Motility: The motility (how well your sperm swim) of smokers had been found to be nearly 13% lower than non-smokers. This could be due to a number of factors, such as impaired morphology (which we'll be getting into later), or even altered semen viscosity/liquefaction time.
Morphology: Smoking affects your morphology (the shape of your sperm) so drastically that there is even a type of defect associated with it: a curved tail. This is especially noticeable in heavy smokers (more than 20 cigarettes per day).
Semen Volume: Several studies have found an inverse relationship between smoking and semen volume (meaning that as smoking increased, semen volume decreased. This is caused largely by the hormonal effects of smoking, as well as the impact of smoking on the circulatory system.
The thing with smoking is, you aren't the only one being affected by it. Chances are, your partner is frequently exposed to your second-hand smoke, which can lead to a longer time to pregnancy, early menopause, and even higher miscarriage rates. Studies have shown that women who were exposed to secondhand smoke were 18% more likely to have these issues, even when she had never smoked a cigarette herself.
Your Future Kids: The other person impacted by smoking? Your future kid. Smoking can lead to elevated levels of ROS, which can damage the DNA stored inside your sperm. If a sperm with damaged DNA manages to fertilize the egg, this could result in various birth defects. Additionally, this DNA damage could result in your son suffering from symptoms similar to the ones we discussed earlier in this article.
The upside of all of this is that most of the effects of smoking on your fertility are reversible. While it will take around 72 days for you to see improvements in your semen parameters, your hormones will bounce back fairly quickly. The steps to getting healthy again are a simple as making the decision to quit. Here's a great resource to help you quit smoking and get your health-and your fertility-back on track.