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How Smoking Harms Fertility
How Smoking Harms Fertility

How Smoking Harms Fertility

We all know that smoking is bad for our health. But now you can blame Dad.

Women who smoke do not conceive as efficiently as nonsmokers. Infertility rates in both male and female smokers are about twice the rate of infertility found in nonsmokers.

Misao Fukuda, M.D. and others at the M&K Health Institute in Japan, studied the health of women whose fathers were heavy smokers. Their study assessed whether paternal smoking habits affect the reproductive life span of daughters.  They found that the smoking habits of the father shortened the daughters’ reproductive life span compared with daughters whose fathers did not smoke. In fact, the average age of menopause came a few years earlier if the woman’s father smoked.

The mechanism for this effect is likely related to passive smoke during childhood and adolescence. Parental smoking does not have a profound effect in a population of women, but passive exposure to cigarette smoke is a significant additive factor in women who are otherwise predisposed to diminished ovarian reserve (DOR) or low ovarian reserve.

DOR may be related to environmental factors which affect a fetus. It’s not surprising that the parents’ smoking habits may affect the ovaries of a daughter. Smoke is full of noxious volatile chemicals.

Two other recent studies found that the number of eggs in human first-trimester ovaries was reduced when the mother smoked. Other studies demonstrated that menopause appeared earlier when the woman herself smoked (active smoking) and when her husband smoked (passive smoking). When the mother smoked (maternal smoking), her daughter also reached menopause earlier.

Of course, these studies only reinforce what we already know: Smoking is harmful to the body in many ways. Now we know that passive smoke inhalation can even affect the ability to have children.

What is diminished ovarian reserve?

While we see diminished ovarian reserve (DOR) most commonly in older ladies, it can happen to patients as young as age 25. That would be pretty rare, but it is not uncommon in the mid-30’s. It can be a cause of what we otherwise would identify as unexplained infertility.

For a long time, doctors did not know that some women simply had prematurely aging ovaries. There are now established criteria for who fits into this category, called the Bologna Criteria, which were established by an international study group. Poor responders have at least two of the three following criteria:

  1. Advanced maternal age (over 40 years).
  2. A previous poor ovarian response (less than three eggs with a conventional ovarian stimulation protocol for IVF). If a patient has three eggs or less, the success rate has been shown to be five percent “take home baby rate” with standard IVF.
  3. An abnormal ovarian reserve test such as a high FSH (over 20), antral follicle count (AFC, less than five) or a low AMH (less than 1.0 ng/ml).

Most of the time we don’t know the reason for DOR, outside of family tendencies and obvious causes like surgery. So it’s a relief to see that there is sometimes an explanation.

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