Is Coffee Bad for Fertility? What the Research Says

Moderate coffee drinking does not appear to reduce your chances of getting pregnant, based on the best available evidence. A systematic review and meta-analysis of studies on natural conception found no clear link between coffee or caffeine intake and a couple’s monthly probability of conceiving. But the full picture is more complicated than that reassuring headline. The risk profile shifts once pregnancy begins, it differs between men and women, and it depends on factors most people have never considered, including their genetics and whether their caffeine comes from coffee, soda, or energy drinks.

Getting Pregnant on Coffee

The most direct version of the question people are asking is whether drinking coffee makes it harder to conceive. For natural conception, the answer from large-scale evidence is mostly no. A dose-response meta-analysis published in Clinical Epidemiology pooled data across multiple studies and found no clear association between coffee or caffeine consumption and natural fertility, whether measured by monthly odds of conceiving or by time to pregnancy.¹ A separate analysis of controlled clinical studies reached a similar conclusion, finding that low, medium, and even high caffeine intake did not significantly increase the risk of infertility.²

An earlier study in The Lancet looked at this from a slightly different angle: researchers surveyed nearly 3,000 women who had recently given birth and compared their time to conceive against their caffeine consumption. Even women drinking more than two cups of coffee per day conceived in about the same time as women drinking almost none.³ These findings are reassuring for people trying to get pregnant who also rely on their morning cup. The effect on getting pregnant, if it exists at all, is small enough that large studies cannot reliably detect it.

Once Pregnant, the Risks Change

Where the evidence tilts toward caution is pregnancy loss. Multiple meta-analyses have found that higher caffeine intake during pregnancy is associated with an increased risk of miscarriage, and the relationship appears to follow a dose-response pattern: more caffeine, more risk. One large meta-analysis of prospective studies estimated that each additional roughly 100 milligrams of caffeine per day, approximately one cup of coffee, was associated with about a 7% higher risk of pregnancy loss.⁴ That same analysis found that the risk was most pronounced at very high intake levels. Women consuming roughly 350 to 700 milligrams per day had about a 40% higher risk, and those above 700 milligrams had about a 70% higher risk, compared to women with minimal caffeine intake.

A separate meta-analysis confirmed the general direction, finding a significantly higher risk of pregnancy loss associated with coffee consumption both before and during pregnancy.⁵ A few caveats apply. These are observational studies, so they cannot prove caffeine directly causes miscarriage. Women experiencing healthy pregnancies may naturally cut back on coffee due to nausea, which could artificially inflate the apparent risk in women who keep drinking at their usual level. Still, the consistency of the findings across study designs and populations is hard to dismiss entirely, and it is the primary reason health organizations advise limiting caffeine during pregnancy to around 200 milligrams per day.

What About Men?

Fertility research has historically focused on women, but caffeine affects men too, and the picture here is surprisingly mixed. A systematic review of studies on coffee, caffeine, and male infertility found that traditional caffeinated drinks like coffee, tea, and cocoa did not seem to harm semen quality in most studies.⁶ Some research even suggested that caffeine might have modest positive effects on sperm, potentially by boosting motility. A review in Andrologia reported that caffeine can enhance sperm movement through several biological pathways, though it also noted that high doses could become toxic to sperm.⁷

The less encouraging findings for men involve sperm DNA integrity. Some evidence suggests that heavy coffee consumption, above roughly 300 milligrams of caffeine per day (about three cups), may be associated with increased double-strand DNA breaks in sperm. Interestingly, at least one study found that caffeine was actually linked to a lower risk of elevated DNA fragmentation, so the evidence points in both directions.⁸ The practical takeaway for men is that moderate coffee drinking is unlikely to cause a problem, but very heavy consumption might warrant a second look if sperm quality is already a concern.

Coffee and IVF

Couples undergoing IVF or similar fertility treatments often get strict lifestyle instructions, and caffeine is frequently on the list of things to limit or eliminate. But the research does not strongly support banning coffee during treatment cycles. A systematic review and dose-response meta-analysis specifically looking at IVF and ICSI outcomes found that neither women’s nor men’s caffeine consumption was significantly associated with pregnancy rate or live birth rate.⁹

A Danish cohort study of women receiving IVF or ICSI treatment also found that coffee consumption did not appear to affect the chance of achieving a clinical pregnancy or a live birth.¹⁰ An Italian prospective study looking at both maternal and paternal caffeine intake during fertility treatment found a slight trend toward more retrieved eggs in women with higher caffeine intake, though the finding was not statistically significant.¹¹ None of this means you should load up on espresso before an egg retrieval, but it does suggest that your morning cup is unlikely to undermine an IVF cycle.

Not All Caffeinated Drinks Are Created Equal

One of the more striking findings in this research area is that the type of caffeinated beverage matters, sometimes more than the total caffeine dose. Several studies have found that caffeinated soft drinks and energy drinks carry different fertility associations than coffee or tea. In one large study of ovulatory disorder infertility, caffeine intake overall was unrelated to infertility risk, and coffee intake appeared to be, if anything, protective. But women drinking two or more caffeinated soft drinks per day had a 47% greater risk of ovulatory infertility compared to women who rarely drank them.¹²

On the male side, the same pattern held. The systematic review that found no harm from coffee, tea, or cocoa did find a negative effect from cola-containing beverages and caffeinated soft drinks on semen volume, count, and concentration.⁶ A preconception cohort study also observed that caffeinated soda and energy drink intake were associated with reduced fecundability among males.¹³

Why would soda be worse than coffee when both contain caffeine? The answer likely has less to do with caffeine itself and more to do with everything else in the drink. Sugary soft drinks and energy drinks tend to come with high sugar loads, artificial additives, and other ingredients that could affect metabolic health and hormonal balance independently. Researchers have noted that disentangling caffeine’s effect from the overall dietary pattern of soda drinkers is a persistent challenge. For practical purposes, if you are concerned about fertility and consuming caffeine, you are probably better off getting it from plain coffee or tea than from sweetened or energy beverages.

Your Genetics May Change the Answer

One reason caffeine studies produce inconsistent results is that people metabolize caffeine at vastly different speeds. The main enzyme responsible for breaking down caffeine in the body is CYP1A2, and genetic variations in the gene coding for it determine whether someone is a fast or slow metabolizer. This distinction has real consequences for reproductive outcomes.

A study of women with recurrent pregnancy loss found that overall, caffeine intake alone was not significantly associated with higher risk. But among women carrying a specific CYP1A2 genetic variant, the risk climbed steeply. Women with two copies of the CYP1A2*1F allele who consumed 300 milligrams or more of caffeine daily had roughly five times the risk of recurrent pregnancy loss compared to lower-intake women with the same genotype.¹⁴ Among women without that variant, the same caffeine intake carried no significant extra risk. This interaction between genes and caffeine has also been observed in birth outcomes: a study in the Hokkaido cohort found that women who rapidly metabolize caffeine and consumed 300 milligrams or more per day had infants with reduced birth weight and head circumference, but only among non-smokers with a specific genotype.¹⁵

You probably do not know which variant you carry, and at-home genetic tests do not always cover this marker reliably. The practical lesson is that blanket advice about caffeine safety limits may not apply equally to everyone. Some people genuinely face higher reproductive risks from the same amount of coffee that is harmless for others. This is a known limitation in the research: studies that average across the whole population may wash out real effects that only show up in genetically susceptible subgroups.

Hormonal Effects Vary by Race and Beverage Type

An often-overlooked finding from the BioCycle Study, a carefully designed investigation of menstrual cycle function in healthy premenopausal women, is that caffeine’s effect on reproductive hormones differed by race. Among white women, consuming 200 milligrams or more of caffeine per day was associated with lower free estradiol. Among Asian women, the same intake was associated with higher free estradiol.¹⁶ The same study found that caffeinated soda and green tea were positively associated with free estradiol across all groups.

These racial differences in hormonal response to caffeine are not well understood, but they underscore an important point: the fertility effects of coffee are not universal. Genetic background, body composition, diet, and the specific beverages consumed all interact in ways that population-level studies can obscure. Data from the same BioCycle cohort also showed that higher blood levels of caffeine and its metabolite paraxanthine were associated with a reduced risk of anovulation, which means skipping ovulation entirely, in premenopausal women. Women in the highest third of caffeine levels had roughly 60% lower odds of anovulation compared to those in the lowest third.¹⁷ That particular finding runs counter to the assumption that caffeine is broadly harmful to female reproductive function.

Animal Studies Tell a More Alarming Story

If you read only the animal research, you would come away much more worried about caffeine and fertility than the human data warrant. Animal models use controlled doses and can measure outcomes that are difficult or impossible to study in humans, but the results do not always translate.

A 2025 study in rats found that caffeine significantly disrupted the estrous cycle, reducing the frequency of every phase, and that progesterone levels dropped and remained suppressed even after caffeine was withdrawn.¹⁸ The researchers attributed this to caffeine’s interference with steroidogenesis, the process by which the body manufactures reproductive hormones, and to caffeine’s activation of the stress hormone cortisol, which in turn suppresses progesterone production. A mouse study found that moderate and high doses of caffeine during early pregnancy impaired embryo transport through the fallopian tubes, disrupted embryonic development, and reduced uterine receptivity, meaning the uterus was less prepared for implantation.¹⁹ Embryos that did manage to implant in caffeine-treated mice had a higher resorption rate and lower birth weight.

These findings are concerning, but the doses used in animal studies are often higher per body weight than what a human coffee drinker would typically consume, and animal reproductive physiology does not map perfectly onto human biology. The value of these studies lies in identifying plausible biological pathways through which caffeine could affect fertility, not in directly predicting human outcomes. They help explain why researchers continue to investigate caffeine despite the relatively reassuring human data on conception.

Coffee Is More Than Caffeine

Coffee contains hundreds of bioactive compounds beyond caffeine, and some of them have properties that could independently affect reproductive health. Chlorogenic acid, one of the most abundant polyphenols in coffee, has attracted particular research interest. In rat models of polycystic ovary syndrome (PCOS), chlorogenic acid improved follicular development, reduced testosterone levels, increased progesterone, and decreased oxidative stress markers.²⁰ A mouse study of PCOS found that chlorogenic acid reduced inflammation and improved ovarian antioxidant defenses through specific cellular signaling pathways.²¹

On the male side, the picture for chlorogenic acid is less straightforwardly positive. A study in mice found that lower doses of chlorogenic acid actually produced more adverse effects on sperm than a higher dose, including increased sperm abnormalities, oxidative imbalance, and DNA fragmentation. The highest dose tested showed the least harm and partial recovery after withdrawal.²² This counterintuitive dose-response pattern is a reminder that the relationship between coffee’s compounds and reproductive biology does not follow simple rules.

These findings suggest that reducing the fertility question to “caffeine versus no caffeine” misses part of the story. Coffee drinkers are also getting antioxidants and anti-inflammatory compounds that may exert their own effects on reproductive tissues. It could be one reason why coffee specifically tends to look neutral or even mildly protective in fertility studies, while other caffeinated beverages that lack these compounds sometimes look worse.

Contaminants in Coffee You Haven’t Thought About

Beyond caffeine and polyphenols, coffee can carry contaminants that are themselves linked to reproductive harm. Mycotoxins, toxic compounds produced by fungi that can grow on stored coffee beans, are one example. Ochratoxin A (OTA) is among the most commonly detected mycotoxins in coffee and has been found in higher concentrations in infertile men compared to fertile men. Aflatoxins, another class of mycotoxin, have been detected in a majority of semen samples from infertile men and correlated with low sperm count and motility.²³ Zearalenone, a mycotoxin with estrogen-mimicking properties, has been linked to menstrual irregularities in adolescent girls.

The relevance to coffee drinkers specifically depends on how the beans were sourced, stored, and processed. Higher-quality specialty coffees generally have lower mycotoxin levels than cheaper commodity-grade beans, though regulation varies by country. This is a factor that virtually no fertility discussion accounts for, but it may partially explain why some studies of heavy coffee drinkers find adverse outcomes that do not appear in other studies. When a study reports that “high coffee consumption” is associated with poorer fertility markers, part of what it may be measuring is higher exposure to these contaminants rather than a pure caffeine effect.