Fact Check: Do Antibiotics Affect Fertility?

If you’re trying to conceive (TTC) — or even just starting to think about your future fertility — you might be wondering whether taking antibiotics could affect your chances of getting pregnant. It’s a smart question to ask, especially since antibiotic treatment is commonly prescribed for everything from urinary tract infections (UTIs) to bacterial vaginosis (BV) and sexually transmitted infections (STIs). But does that prescription actually impact your fertility?

Let’s dig into what we know (and what we don’t) about how antibiotics may affect your reproductive health.

How do antibiotics work?

To understand how antibiotics may or may not affect your chances of conceiving, it’s helpful to understand how they work in the first place. 

Antibiotics are medications that fight bacterial infections by killing or stopping the growth of bacteria. They're lifesavers in many cases, especially when it comes to reproductive health.

However, like any medication, antibiotics can have side effects, especially if taken too often or when not needed. Overuse of antibiotics can lead to antibiotic resistance, where bacteria no longer respond to treatment. That’s one reason why Evvy’s Vaginal Health Test includes an Expanded PCR Panel that screens for 11 common antibiotic resistances, so you and your provider can choose the most effective treatment if needed.

Do antibiotics affect fertility?

The short answer is: there’s no strong evidence that antibiotic treatment directly harms female fertility. While some studies have raised questions about certain antibiotic classes, the results are inconsistent and often influenced by the underlying infections for which the antibiotics were prescribed in the first place.  It is important to note that certain antibiotics aren’t recommended for use during pregnancy, so if you’re trying to conceive, make sure you check with your doctor before taking any new medication. 

The relationship between antibiotics and fertility is a bit complex (as is fertility itself). Some research has linked preconception antibiotic treatment with slightly lower chances of conception, early miscarriage, or congenital malformations. However, these effects appear to be limited to certain antibiotic classes (like macrolide antibiotics or sulfonamides) and are still not well understood. Many experts believe that these associations are more about the infections themselves than the medications used to treat them.

So while routine antibiotic therapy doesn’t seem to impair fertility directly, the real concern is what happens if infections go untreated, and that’s where antibiotics play a critical role.

Fertility and infections

Many bacterial infections that require antibiotics — such as chlamydia, gonorrhea, and bacterial vaginosis — have been linked to reduced fertility or complications in pregnancy. Untreated pelvic inflammatory disease (PID) or chronic endometritis can cause lasting damage to the reproductive tract, leading to tubal factor infertility, ectopic pregnancy, or recurrent miscarriage.

In these cases, antibiotics are essential to preserving fertility, not harming it. Research even shows that successful antibiotic treatment of chronic endometritis is associated with improved pregnancy outcomes in women with a history of reproductive failure.

So while it’s understandable to be cautious about taking medications when trying to conceive, skipping antibiotics for a reproductive tract infection could do far more harm than good.

What antibiotics are safe when TTC?

Most antibiotics are safe to take when trying to conceive, especially if prescribed for a known infection. But it’s a good idea to be aware of which ones might carry slightly more risk and to discuss your options with your provider.

Generally considered safe when TTC:

• Penicillins (e.g., amoxicillin)
• Cephalosporins
• Clindamycin 

Used with caution:

• Macrolide antibiotics (e.g., azithromycin, erythromycin): Some studies suggest a weak association with reduced fertility, but it may reflect the underlying infection more than the drug itself.
• Sulfonamides: Also associated with slightly reduced fecundability in some research.
• Tetracyclines: Avoid in pregnancy, though they may be used before conception under medical guidance.

Always talk to your healthcare provider before starting or stopping antibiotics, especially if you’re actively trying to get pregnant. They’ll weigh the benefits of treating an infection against any potential risks to your fertility or pregnancy.

Antibiotics and the vaginal microbiome

Another layer to consider is how antibiotics affect your vaginal microbiome, the delicate balance of bacteria in your vaginal ecosystem. Certain antibiotics can disrupt this balance, especially when taken frequently, potentially making it easier for BV or yeast infections to recur.

A disrupted vaginal microbiome has been linked to infertility, miscarriage, and even poor IVF outcomes. That’s one reason it’s so important to restore and maintain a healthy vaginal environment before and during pregnancy. Evvy’s Vaginal Health Test can help you understand your microbiome and make data-informed choices.

Animal studies have even suggested that gut dysbiosis (an imbalance of gut bacteria caused by antibiotics) might affect reproductive function, but these findings haven’t been confirmed in humans and shouldn’t guide clinical decisions at this time.

Can antibiotics affect male fertility?

Antibiotics can potentially affect fertility in men as well. While some studies suggest that certain antibiotics may temporarily reduce sperm count or motility, this is a poorly researched area.

Also, it is important to remember that, just like in women, these effects are usually reversible, and the bigger risk often lies in the infection being treated. STIs like chlamydia can damage sperm quality and affect overall reproductive health in men if left untreated.

The takeaway

So, do antibiotics affect fertility? In most cases, no, not directly. While some studies suggest possible links between certain antibiotic classes and slightly reduced chances of conception, the evidence is weak and likely influenced by the infections themselves. On the flip side, untreated bacterial infections can cause serious and lasting harm to fertility, making appropriate antibiotic treatment absolutely essential.

If you’re planning a pregnancy or currently trying to conceive:

• Don’t avoid antibiotics out of fear, but do use them wisely.
• Talk to your healthcare provider about any medications you’re prescribed.
• Consider testing your vaginal microbiome with tools like Evvy’s Vaginal Health Test, which now includes Fertility Insights to help you stay on top of your reproductive health.

FAQ

Can antibiotics affect the ovulation cycle?

No, antibiotics don't affect your ovulation cycle or the hormones that help regulate your period. Lots of reliable sources agree that there's no solid scientific proof suggesting that the antibiotics we commonly use have an impact on menstruation, ovulation, or fertility in women.

Can you be on antibiotics and be pregnant? 

Yes, you can be on antibiotics while pregnant. Many antibiotics are considered safe and are commonly prescribed to treat infections, including vaginal infections like BV or UTIs. Safe antibiotics during pregnancy include penicillins (e.g., amoxicillin), cephalosporins (e.g., cephalexin), and clindamycin. These are often used to treat BV, group B strep, and other vaginal or urinary infections. However, some antibiotics — like tetracyclines, sulfonamides, and fluoroquinolone antibiotics — are usually avoided during pregnancy due to potential risks to the baby. Always consult your healthcare provider before starting or stopping any medication while pregnant or trying to conceive.

Can antibiotics cause a delay in pregnancy?

Most antibiotics don't greatly affect fertility or delay pregnancy for most women. A large study showed that women who took antibiotics in the last four weeks had similar chances of getting pregnant as those who didn't take antibiotics, with only small differences between types of antibiotics. However, some types, like macrolide antibiotics (such as azithromycin) and sulfonamides, may lower fertility and increase the risk of infertility before conception. Often, though, the infection being treated can cause fertility problems on its own, making it hard to tell how much of the issue comes from the antibiotics versus the infection. It's also worth pointing out that antibiotics can also help improve fertility by treating bacterial infections that might block conception.

What medications can cause female infertility? 

Several medications and substances can influence female fertility in different ways, such as affecting ovulation, hormone levels, or potentially harming the reproductive organs. Some prescription medications, like certain antipsychotics, immunosuppressants, and certain chemotherapy drugs, fall into this category. Additionally, recreational drugs like cannabis and opioids can also have an impact. It's always a good idea to discuss any concerns with a healthcare professional who can provide more personalized information.