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Caffeine and Fertility

Does Caffeine Affect Fertility?

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Updated May 27, 2014

Woman smiling looking out window with coffee
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A question on the minds of many women trying to get pregnant is whether the caffeine in their morning cup of coffee affects their fertility. The possible connection between caffeine, fertility, and miscarriage rates is commonly in the news, perhaps because the research interests so many women. Having a morning cup of coffee or tea is practically a tradition in the Western world.

Also, getting our bodies in tip-top shape is often a primary goal when trying to get pregnant, and many aspire to give up that morning cup of coffee or tea. Some women, though, just cannot get through the day without a bit of a caffeine boost. For them, a morning or afternoon cup of joe can lead to feelings of guilt and worry.

What does the research actually have to say about caffeine and fertility? Is there any reason to feel guilty over just one cup of coffee?

To get more details on the connection between caffeine and fertility, read this excerpt from UpToDate -- a trusted electronic reference used by many physicians and patients.

Then, read on for what all of this means for you.

"Approximately 20 percent of adult Americans consume greater than 300 mg of caffeine daily. Some studies have reported that increased caffeine consumption (eg, >300 to 500 mg) is associated with a modest, but statistically significant decrease in fertility, while others have not found an adverse effect. The widespread consumption of caffeine at doses associated with subfertility makes it a potentially important contributor to fertility problems. The March of Dimes website recommends that women who are trying to become pregnant consume no more than 200 mg of caffeine per day.

"The mechanism by which caffeine consumption may be linked to infertility is unclear. Caffeine consumption may increase estrogen production and/or decrease estrogen metabolism. Caffeine consumption has also been linked to tubal factor infertility and endometriosis associated infertility. Most studies were done in coffee drinkers and do not account for other sources of caffeine or other substances in coffee that may affect fertility.

"There is no strong evidence that caffeine consumption by the male partner influences fertility. Whether caffeine consumption impairs success of in vitro fertilization is unclear due to lack of studies."

Factors to Keep in Mind When Looking at the Research

As the excerpt above states, whether or not caffeine leads to lowered fertility is unclear. While some studies have shown an effect on fertility, other studies have shown no effect. Even in studies that have found an effect on fertility, it's not a strong one.

When you've been trying to conceive for a long time, you're probably wary of taking in substances that even might make trying to get pregnant difficult. So while the research doesn't implicate caffeine completely, cutting back may be a good idea, just in case.

Something else to keep in mind when looking at the research on caffeine is that it's not clear whether it's the caffeine that may lead to problems with fertility, or other lifestyle choices which caffeine drinkers may be more likely to take part in.

For example, people who smoke are more likely to drink a lot of coffee and alcoholic beverages. So when a study finds fertility problems in women who drink coffee, is it the coffee? Or could it be the women who are also smoking that are leading to the lower fertility rates in the study? In many research studies, it's impossible to tell.

Caffeine, Endometriosis, and Estrogen

Some studies have found that caffeine may have an effect on estrogen levels, specifically leading to higher circulating levels. Other studies have found that for those struggling to conceive, caffeine drinkers may be more likely to have endometriosis, as opposed to other causes of infertility.

Since high levels of estrogen can make endometriosis worse, if caffeine does have an effect on estrogen, this may be the connection. If you have endometriosis, you might want to more seriously consider cutting back on caffeine.

How Much Caffeine Is in a Cup of Coffee? A Cup of Tea? A Chocolate Bar?

Most of the research on caffeine consumption and fertility has focused on coffee drinkers. It's assumed that the caffeine is the cause of any potential problems with coffee, but it could be other substances found in coffee.

That being said, if you want to play it safe with caffeine, taking in less than 200 mg of caffeine a day is recommended. However, most of us don't think of our caffeine-fix in terms of milligrams, but in terms of cups.

How much caffeine is in a cup of coffee or tea? How about soft drinks? Here are some general guidelines, from UpToDate:

For coffee:

  • Drip (8 oz) = 234 mg
  • Percolated (8 oz) = 176 mg
  • Regular instant (8 oz) = 85 mg
  • Decaffeinated instant (8 oz) = 3 mg
  • Expresso (1 -2 oz) = 45 to 100 mg
  • Starbucks grande (16 oz) = 330 mg

For tea:

  • 1 minute brew = 9 to 33 mg
  • 3 minute brew = 20 to 46 mg
  • Instant = 12 to 28 mg
  • Canned ice tea (12 ounces) = 22 to 36 mg

For soft drinks:

  • Dr. Pepper = 39.6 mg
  • Regular cola = 46 mg
  • Diet cola = 46 mg

For cocoa and chocolate:

  • Cocoa from mix (6 oz) = 10 mg
  • Milk chocolate (1 oz) = 6 mg
  • Baking chocolate (1 oz) = 35 mg

The Bottom Line on Caffeine and Fertility

Studies have not found a connection between caffeine and lowered fertility in men.

While it's not clear yet whether caffeine lowers fertility in women, the studies that have shown an effect find that less than 200 mg of caffeine should be ok. You don't have to give up your morning cup of coffee (and needn't feel guilty about it), but you might want to pass on seconds.

Want to learn more? See UpToDate's topic, "Optimizing natural fertility in couples planning pregnancy", for additional in-depth, current and unbiased medical information on infertility, including expert physician recommendations.

Source:

Olek, Michael J., Gibbons, William E. "Optimizing natural fertility in couples planning pregnancy." UpToDate. Accessed: September 2009.

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