It's no secret that smoking is detrimental to your health, so it should be no surprise that smoking can affect your fertility. However, for many women, it apparently is surprising.

One survey of women of childbearing age found that only about 30% knew that smoking could increase their risk of miscarriage. Even fewer (about 10%) knew that smoking could hurt their fertility.

Smoking has been linked to an increased risk for many cancers, heart disease, emphysema, and a number of other health problems. The toxins contained in cigarettes take their toll not only on your lungs but on your entire body's health, including your reproductive system.

Smoking habits may be responsible for fertility struggles in as many as 13 percent of couples.

How Much Smoking Is a Problem?

Because smoking can harm a child prenatally, it's a good idea to quit smoking before you even consider pregnancy.

That being said, if you decide not to quit smoking before you start trying to conceive, you may have trouble getting and staying pregnant in the first place.

How much do you need to smoke to have a measurable impact on your fertility?

According to a 2017 study on the subject, six or more cigarettes per day will significantly harm your ability to conceive. This doesn't mean smoking fewer cigarettes per day would not lead to lowered fertility. But it is clear that smoking six or more a day increases your risk of developing problems.

Other studies have shown that for each cigarette smoked per day, the longer it will take for the couple to get pregnant.

For example, a woman who smokes four cigarettes per day will on average take more time to get pregnant than a woman who smokes just two per day. If quitting completely does not seem to be in the cards for you, cutting back is still worth trying for.

How Smoking Hurts Your Fertility

Smoking is associated with the following fertility problems:

Problems with the fallopian tubes, including blockages (preventing egg and sperm from meeting) and an increased risk of ectopic pregnancy
Damage to the eggs as they develop in the ovaries
Increased risk of miscarriage, possibly due to damaged eggs, damage to the developing fetus, or unfavorable changes in the uterine lining, which may make healthy implantation of an embryo less likely
Cervical changes, specifically an increased risk of developing cervical cancer

It's important to point out that not all of these issues are directly caused by smoking. They may be associated with each other. Practicing unsafe sex can also increase the risk of pelvic infection and blocked fallopian tubes, for example. However, in the case of damage to the eggs in the ovaries, this is likely a direct cause of smoking.

Smoking May Shorten Your Biological Clock

Some studies have shown that smoking can cause not only problems with fertility while you're smoking, but lead to lowered fertility in the future.

Men produce new sperm throughout their lives, but women are born with all the eggs they will ever have. Once those eggs are damaged, there's no going back. Smoking may decrease the total number of eggs a woman has in her ovaries and cause the ovaries to age prematurely.

Toxins in cigarettes may also lead to DNA damage to the ovarian follicles, where the eggs normally develop to maturity.

This premature aging of the ovaries and decrease in eggs may lead to earlier menopause, as much as four years earlier than normal.

Birth Defect Risks of Smoking During Pregnancy

Smoking during pregnancy is associated with miscarriage, low birth weight, and premature birth. Another important reason to quit smoking before you conceive is to reduce your risk of birth defects.

Because many birth defects occur very early in pregnancy—sometimes before a woman even realizes she has conceived—waiting until you get pregnant is not enough to reduce the risk of harm to your unborn child.

A large systematic review on smoking and birth defects—which included 11.7 million controls and just over 170,000 children with congenital defects—found that smoking during pregnancy increased the risk of:

Heart and cardiovascular defects
Limb defects (where an arm or leg fails to grow fully or is completely missing)
Missing (or extra) fingers or toes
Clubfoot
Cleft lip or palate
Skull malformations
Facial and eye deformations
Hernia
Gastrointestinal defects
Anal defects
Undescended testes

The study also found that babies of smokers were more likely to have two or more congenital defects when compared to the babies of non-smokers.

A Word From Verywell

Don't feel that there's no turning back after years of cigarette smoking.

While smoking can lead to some long-term fertility damage, studies have also shown that fertility rates can improve after one year of quitting.

Some women may be tempted to keep smoking until they get pregnant. However, it's best for you and your future baby if you quit before you achieve pregnancy.

Quitting smoking before you even start trying to get pregnant may:

improve your chances of conceiving
be easier on your body
healthier for your baby
lower the risk of miscarrying the pregnancy
lower the risk of birth defects for your baby

If your partner is also a smoker, consider quitting together. There are many good reasons to do so. His secondhand smoke may lower your fertility and threaten your pregnancy, and some studies have found that smoking lowers male fertility as well. This is not to mention the health problems that can arise in babies and children who are exposed to secondhand smoke.

Dropping the habit together will increase your chances of successfully quitting, too.