31 May Smoking and Pregnancy
Smoking is one of the modifiable factors that impacts fertility. Studies have demonstrated that women who smoke are 1.6 times are likely to be infertile than women who don’t. Additionally, women who smoke go through menopause 1-4 years earlier than non-smokers.
The increased risk of infertility and earlier menopause suggest that smoking likely impacts egg supply. Our current understanding is that women are born with all of the eggs they will have. At 20 weeks in-utero the ovaries have 6-7 million eggs. This drops to 1-2 million at birth and around 0.5 million by puberty. The egg supply continues to decline until menopause, average age of 51 years. Generally, only one egg is used, or ovulated, each month, but the ovary goes through hundreds to thousands of eggs to select and ovulate a single egg. The remaining unused eggs for that month die off. Smoking likely decreases the total number of eggs and, as a result of the decreased egg supply, menopause comes early.
Tobacco use among men does not impact fertility as significantly as it does in women. Some studies have demonstrated lower sperm parameters (concentration, movement, and shape) on semen analysis among men who smoke, but studies have not conclusively demonstrated reduced fertility. However, second hand smoke has been shown to increase the risk of low birth weight babies.
Men and women should stop smoking as soon as possible for overall health benefits. This is especially important for those trying to create a pregnancy due to the infertility, pregnancy, and neonatal risks.
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