Written by: Dr. Olivia Carpinello, a reproductive endocrinology and infertility specialist at CCRM Fertility of Northern Virginia
I know, I know. You’ve heard it once, you’ve heard it a million times. “You should really quit smoking.” Most people who smoke know they shouldn’t do it, but it’s hard to quit! You know it’s “bad” for your health, but did you know smoking also makes it harder to become pregnant, stay pregnant, and have a healthy baby? Here are the top 10 ways smoking can harm your fertility:
1. Tubal damage
Our fallopian tubes are lined with tiny little cilia (imagine fine bristles on a brush) that gently beat to pick up and transport the ovulated egg and the sperm. These fragile cilia are what allow the egg and sperm to meet. Smoking impairs the function of the cilia, which can prevent fertilization.
2. Ectopic pregnancy
Ectopic pregnancies are abnormal pregnancies that have implanted outside of the uterus, most commonly in the fallopian tube. Ectopic pregnancies can cause loss of a fallopian tube or ovary and can be life threatening. Not only are the tubal cilia responsible for the sperm and egg meeting, but they are also responsible for transporting the newly fertilized egg (now a developing embryo) into the uterus for implantation. When the cilia are damaged, the embryo is more apt to not be transported to the uterus for implantation. Because the tubes are not functioning as they should, smokers are at an increased risk for ectopic pregnancy.
3. Miscarriage
Women who smoke are at a higher risk of having a miscarriage when they do become pregnant. This may be due to a variety of reasons. One leading possibility is that the toxins in tobacco smoke lead to DNA damage and damage to the “machinery” in the egg that is responsible for chromosomes separating normally. However, the increased risk of miscarriage is not solely attributable to toxins in tobacco smoke, as use of smokeless tobacco products (i.e. vaping) is also associated with an increased risk of miscarriage. Nicotine, itself, may play a role in preventing adequate blood flow to a developing pregnancy, increasing the risk of miscarriage.
4. Earlier menopause
Women are born with all the eggs they are ever going to have. It’s a very sad fact of life! Every month, we lose a group of eggs- one egg “wins” and ovulates, and the rest in that small group die off. As we start to run out of eggs, we approach menopause. Women who are smokers were found to go through menopause 1-4 years earlier than their nonsmoking peers. It is thought that the toxins in tobacco smoke are responsible for killing off our eggs at a faster rate. As a result, smokers tend to run out of eggs sooner than nonsmokers.
5. Worse in vitro fertilization (IVF) outcomes
These days, most women have heard of in vitro fertilization. For some, it is their backup plan: “If I have trouble getting pregnant, I can always do IVF.” While IVF has allowed us to help A LOT of people who otherwise would have been unable to become pregnant, it still has a long way to go and is not always successful. For IVF to work, we need healthy eggs and sperm. Because women who smoke have fewer, less healthy eggs, it can be harder for their ovaries to respond to IVF medications. According to the American Society for Reproductive Medicine (ASRM) committee opinion on smoking and infertility, even when women who smoked used donor eggs (eggs from a younger, nonsmoking woman) to create embryos, there were lower live birth rates, suggesting smoking also affects the uterus. Some studies have estimated that smokers need approximately twice the number of IVF cycles as nonsmokers to have a successful, ongoing pregnancy.
6. Sperm abnormalities
The guys aren’t off the hook! Smoking and smokeless tobacco has been shown to lead to abnormal sperm parameters such as decreased concentration, lower sperm motility, and abnormally shaped sperm. Additionally, there is evidence to suggest that the sperm of smokers (and partners of smokers) have a harder time fertilizing the egg. This contributes to the worse IVF outcomes mentioned above.
7. Preterm delivery
Smoking is a known risk factor for preterm delivery. A baby born prior to 37 weeks is considered preterm. Babies born prematurely often spend days to months (depending on how early they were born) in the neonatal intensive care unit (NICU), and are much more apt to have severe complications, including underdeveloped brains and lungs, as well as death.
8. Small babies
Not only are babies at risk for being born early, but they are also at risk of being small, even if born full term. Babies born small for gestational age (SGA) are at an increased risk of death, learning disabilities, autism and behavioral problems than their normal-weight peers born at the same gestational age.
9. Birth defects
Due to the DNA damage and damage to the machinery responsible for the normal separation of chromosomes, birth defects and conditions such as Down’s syndrome are more common in children born to smokers.
10. Cervical and ovarian cancer
Most people are aware of the increased risk of lung cancer, but did you know smoking raises the risk of just about every cancer? Human papilloma virus (HPV) is the virus responsible for most cases of cervical cancer. HPV is incredibly common; most sexually active adults will have had it at some point in their lives. In many cases, the body is able to fight off this virus, and the abnormal changes detected on pap smear go away on their own. However, smoking impairs our body’s ability to fight this virus. As a result, smokers have a much higher chance of having cervical cancer than their nonsmoking peers. If you have an abnormal pap smear, the BEST thing you can do to help your body clear the virus is to quit smoking. Treatment of both cervical and ovarian cancer can lead to infertility due to surgery to remove the reproductive organs or chemotherapy.
So what can you do? Work on quitting! I’m not saying it is going to be easy. Nicotine is addictive, and cutting out tobacco requires a huge lifestyle change. Do it with your partner, friends and family. Even second-hand smoke harms fertility. (For tips to quit smoking, check out the quitSTART app.) The bad effects of smoking are “dose-dependent,” meaning, the more you are able to cut out, the better off you will be. Even baby steps on the path to quitting can be beneficial! Don’t give up hope – many of these bad effects are reversible if you are able to quit or significantly reduce the amount you smoke.
