Are Antibiotics Safe During Pregnancy?

After getting a positive pregnancy test, your body is in for lots of change. But what you probably didn't know is that all those changes can create the ideal environment for infections—and possibly the need for antibiotics.

But rest assured that needing antibiotics during pregnancy is quite common. The Centers for Disease Control and Prevention's National Birth Defects Prevention Study (NBDPS) of more than 13,000 pregnant people found that about 30% of them had at least one course of antibiotic treatment between the three months prior to conception and the end of their pregnancies, most commonly during the fourth month of pregnancy.

Luckily, many commonly used antibiotics are considered safe for use during pregnancy. However, research shows that certain antibiotics can potentially cause congenital abnormalities. This is worrisome to parents who may feel they face a hard choice: To take the antibiotic and get better but risk a congenital disorder, or skip it and risk complications from the infection.

But don't worry: According to experts, the issue isn't that black and white. There are many pregnancy-safe antibiotic options available. Here, we provide tips on keeping both you and your baby healthy when you require treatment with antibiotics.

Types of Infections

First off, it's important to know that there are many different types of infections, including bacterial, fungal, and viral infections. Antibiotics only treat bacterial infections. They aren't prescribed for viral or other non-bacterial infections because they don't work against those types of microorganisms.

It's important not to use antibiotics when they're not needed or effective because overuse of antibiotics leads to drug-resistant bacteria, which can mean that when you do need antibiotics, they might not work. Other treatments may be available to manage non-bacterial infections. However, if you do have a bacterial infection that needs treatment, using antibiotics can be very effective.

Bacterial Infections During Pregnancy

Common bacterial infections during pregnancy include urinary tract infections (UTIs) and group B strep. For these infections, antibiotics are the only medications that will help you get better, and you should take them despite the potential risk to your baby.

Why? In some cases, not treating your infection could be much riskier for your baby's health than exposing them to an antibiotic, according to Komal Bajaj, M.D., MS-HPEd, OB-GYN, reproductive geneticist, and Chief Quality Officer at NYC Health + Hospitals/Jacobi in New York City.

Your prenatal care provider will be aware of which antibiotics to avoid during pregnancy and is trained to prescribe the ones that have better safety records.

Taking Antibiotics While Pregnant

"The umbrella term 'antibiotic' can be scary to pregnant women," Dr. Bajaj says. "While it's prudent to be cautious, antibiotics are an important part of our clinical practice." If you do have a bacterial infection, your doctor will carefully choose which antibiotic should be prescribed, as all antibiotics are different, says Dr. Bajaj.

The FDA's pregnancy categories for drugs

While many medications are completely safe to take during pregnancy, others can cause serious complications for the fetus. The Food and Drug Administration (FDA)'s list of Pharmaceutical Pregnancy Categories helps medical providers (and their patients) know the prenatal safety of medications. The categories are A, B, C, D, and X. To break it down, here is what the different categories mean.

• Category A: Shown to be safe for pregnant people
• Category B: Animal studies did not show risk to the fetus; no adequate human studies
• Category C: Animal studies showed adverse effects on the fetus or no animal or human studies
• Category D: Animal studies showed increased risk to the fetus, but the benefits may outweigh the risks
• Category X: Animal studies show clear risk and no benefits.

Drugs within Category A are safe for use in pregnant people, whereas drugs within Category X are harmful to fetuses and should not be used during pregnancy. The other categories fall between these extremes. Category B drugs have been found safe in animal studies and are thought to be relatively safe in humans. Category C drugs have evidence of increased risk of harm in animal studies but not definitively in human data. Category D has evidence of increased risk of harm to human fetuses, but use during pregnancy still may be warranted in some cases.

If you are pregnant or are trying to become pregnant, ask your medical provider about the pregnancy categories of any medications you are prescribed. You can also find the pregnancy category designation of each medication on its package insert.

What are the potential risks?

Congenital disorders associated with antibiotics defined within Category X include anencephaly (a fatal malformation of the skull and brain), choanal atresia (a blockage of the nasal passage), transverse limb deficiency, diaphragmatic hernia, eye defects, congenital heart disorders, and cleft palate.

Category A and B drugs

The FDA requires a relatively large amount of high-quality data on a medication for a drug to be classified within Pregnancy Category A, and it is common for pregnant people to safely take Category B medications, such as the antibiotic Augmentin (amoxicillin and clavulanate).

Augmentin is commonly used to treat bacterial infections such as sinusitis and pneumonia, which can be harmful to a pregnant person and their baby if left untreated. The drug has undergone animal reproduction studies and appears to have no negative effect on pregnancy, says Aleksandr M. Fuks, M.D., an OB-GYN at NYC Health + Hospitals in New York City.

Penicillin, the most commonly used antibiotic during pregnancy, has not been found to be associated with increased risk for about 30 different congenital disorders, according to The National Birth Defects Prevention Study.

The reality about drug safety classifications

Ethical considerations preclude conducting drug trials in pregnant people, so for many drugs, adequate and well-controlled studies have not been done, Dr. Fuks says. There might be negative fetal effects associated with some Category B drugs that aren't currently recognized, for example.

"[Medications] should only be prescribed in situations where the health care provider strongly believes that the benefit of its use largely outweighs any possible risks to the fetus and the pregnancy," Dr. Fuks says.

Though many antibiotics such as penicillin have been used safely for decades, resistant strains of bacteria are forcing medical providers to use a wider array of antibiotics. Safety depends on various factors, including the type of antibiotic, when in your pregnancy you take the antibiotic, dosage, and duration of use.

Putting elevated risks in perspective

Even if an antibiotic has been linked to an elevated risk of congenital disorders, the chances remain small. For example, the risk of having a child with hypoplastic left heart syndrome is about 1 in 4,200. Sulfonamide antibiotics are associated with a threefold increase, making the likelihood about 1 in 1,400, according to the National Center on Birth Defects and Developmental Disabilities.

Safe and Unsafe Antibiotics During Pregnancy

Some antibiotics commonly considered safe for use during pregnancy include but are not limited to:

• Augmentin
• Amoxicillin
• Ampicillin
  
• Cephalexin
• Clindamycin
• Erythromycin
• Penicillin

Some antibiotics commonly considered unsafe for use during pregnancy include but are not limited to:

• Bactrim
• Ciprofloxacin
• Doxycycline
• Minocycline
• Septra
• Tetracycline

Clarithromycin and azithromycin in pregnancy

In a study published in the journal Pharmacoepidemiology and Drug Safety, researchers investigated whether there was any link between taking a class of antibiotics known as macrolides—which include azithromycin and clarithromycin—during pregnancy and having a baby with a congenital disorder.

Using data from over 135,000 pregnant women (nonbinary people were not represented in this data) in the Quebec Pregnancy Cohort, researchers compared the outcomes of those who'd taken macrolides, those who'd taken penicillin, and those who hadn't taken any antibiotics.

"We did not find a statistically significant association between macrolide use during pregnancy and the risk of malformations," says study author Anick Bérard, Ph.D., a professor in the Faculty of Pharmacy at the University of Montreal and a researcher at its affiliated CHU Sainte-Justine hospital. "This is reassuring when treating infections during pregnancy."

The FDA classifies azithromycin as a Category B drug, which means it has been shown as safe in animal studies. Clarithromycin is Category C, which means it has been shown to have negative effects in animals. Neither group has had well-controlled studies in humans, but data is collected to monitor for any increased incidences of congenital disorders in babies born to people who took the drugs during pregnancy.

Talk to a Medical Provider

No matter what you and a medical provider decide is the right course of action in the case of infection, communication is key. Speak with all medical providers you work with about any medications you are taking to avoid drug interactions, and always tell or remind health care providers that you are pregnant or trying to get pregnant when receiving prescription medications or medical care.

You should also make your prescriber aware of any allergies or health conditions you may have, such as kidney disease, liver disease, history of hepatitis or jaundice, or mononucleosis, as your full medical history can impact which antibiotic is safest for you, says Dr. Fuks. If you experience any side effects or if the infection is not clearing, you should also alert your prescribing physician.

The Bottom Line

While it can be scary to consider taking medications during pregnancy, many antibiotics are considered safe for you and your growing baby. Treating any infections is crucial as they typically pose a much greater risk to the health of your pregnancy. Consult with your medical provider if you have any questions or concerns. However, know that your medical provider will choose the safest medication option they can to protect the health of both you and your baby.