Does coffee affect fertility?

A 1988 study seemed to show that women who drank about a cup of coffee a day were half as likely to fall pregnant. This set the stage for a great deal of excitement and debate on the topic of coffee and fertility. Although this study has been cited repeatedly over the decades, no subsequent study has actually been able to replicate the results of this initial study.

It is indeed difficult to explicitly answer this question, but there have been other studies on this subject. One of the most comprehensive studies included slightly more than 3000 Danish women. The study examined fertility rates in relation to women’s intake of coffee, tea, and soft drinks. The following findings were the result of the study:

• Women who consumed more than 300 mg of caffeine per day – that is, more than 1 cup of coffee, showed very similar fertility rates to women who consumed less than 100 mg to no caffeine daily.
• Women who drank two or more cups of tea per day showed a slightly higher chance of falling pregnant than women who did not consume tea at all.
• Women who drank soft drinks were less likely to become pregnant in a given cycle compared to women who drank no soft drinks at all. Women who drank three servings of soft drinks per day showed worse fertility rates than women who drank only one serving per day.

But what do these results mean? Well, the researchers actually couldn’t figure out for sure why in this study the women who drank tea showed higher fertility rates and the women who drank soft drinks showed lower fertility rates.

Another study published in 2017 compiled data from previously published research to examine the possible dose-dependent effects of caffeine or coffee for the time span pre-conception. This included couples who wanted to conceive naturally, as well as those who underwent fertility treatment. The risk of miscarriage associated with caffeine consumption was also investigated.

The following findings were the result of this study:

• Caffeine consumption of 300 mg increases the risk of miscarriage.
• Consumption of 600 mg of caffeine resulted in a more than doubled risk of miscarriage.
• However, caffeine did not appear to affect the length of time it took couples who wanted to conceive naturally to become pregnant.
• Caffeine consumption also did not appear to have a negative effect on couples undergoing fertility treatment.

To answer this question, it is necessary to consider how caffeine acts in the body (especially in the bodies of individuals with female physiology). The following should be considered:

According to one study, caffeine consumption can stimulate cortisol release. Cortisol is commonly known as the ‘stress hormone’. Caffeine also causes the heart rate to accelerate and blood pressure to rise, which can also signal stress to the body.

One of the suspected reasons for this is that women’s bodies are more likely to hold on to fluids in the body, primarily to maintain energy levels.

The production of estrogen is also said to be negatively affected by the consumption of coffee. According to one study, a negative effect on estrogen levels is said to be particularly noticeable in white women.

Coffee can promote acidity in the body. This can contribute to period pain and PMS symptoms.

Important micronutrients that our bodies need to function healthily may not be adequately absorbed when consuming coffee. Coffee also has a diuretic effect, which means that water-soluble nutrients are also increasingly flushed out of the body due to coffee consumption.

The stimulant effect of coffee works by first stimulating the production of ATP (AdenosineTriPhosphate) in the body. ATP is an essential building block needed for the body to be able to produce energy. However, this only lasts for a short time and chronic stimulation of ATP can, unfortunately, cause the body to gradually ‘burn out’. Thus, the energizing effect of consuming coffee is not an actual energy boost, but a chemically induced stimulation of ATP. In the long run, over-stimulation can lead to prolonged states of exhaustion and fatigue.

Consuming coffee increases norepinephrine, which stimulates the nervous system. At the same time, however, it also tends to reduce the neurotransmitter serotonin, which tends to have a calming effect.

Caffeine consumption in men has been linked to increased testosterone and SHBG (sex hormone binding globulin). Coffee has been reported to alter the glycolytic and oxidative properties of certain cells, which may affect reproductive function in men. It should be noted that the mechanism by which caffeine affects the body has not yet been fully explored. However, it is known that caffeine can have a modifying effect on the hormonal system. According to a comprehensive study, the consumption of coffee may affect male reproductive function. However, a link between caffeine consumption and male reproductive health could not directly be demonstrated.

The study examined the relationship between male fertility in relation to stress, coffee and caffeine consumption, and other lifestyle factors. Some studies showed that beverages such as soft drinks and caffeinated beverages negatively affect the volume, number, and concentration of sperm. Coffee and other caffeinated beverages may be associated with diet or lifestyle habits, and it is unfortunately very difficult to distinguish between false and possible associations here. Soft drinks may be more informative than coffee. The associations found in men who drank large amounts of caffeinated soft drinks could not be explained solely by the caffeine content of the drink, some of which were actually not very high. Rather, it could simply be the case that these men led less healthy lifestyles. Caffeinated beverages could affect fertility in ways that are not directly related to the caffeine they contain. For example, soft drink consumption could lead to lowered fertilty rates simply by increasing the likelihood of developing insulin resistance, metabolic dysfunction and weight gain. Soft drink consumption in general has appeared to affect sperm quality in studies.