Antibiotics and Pregnancy

Can you take antibiotics while pregnant? Here's what you need to know about the advantages – and the possible side effects.

After getting a positive pregnancy test, your body is in for lots of change. But what you probably didn't know is that change can lead to infection – and more antibiotics.

A recent National Birth Defects Prevention Study of more than 13,000 pregnant women found that about 30 percent of women undergo 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.

Select antibiotic use has the potential to cause congenital abnormalities in newborns. So do you take the antibiotic and get better, or skip it and risk birth defects? Don't worry – according to the study, it's not that black-and-white, and there are safe options available. Here, we provide tips on keeping both you and your baby healthy.

Infections and Antibiotics

Viral Infections

Viral infections should not be treated with antibiotics for two reasons:

  1. It won't get rid of the infection.
  2. Overuse of antibiotics leads to drug-resistant bacteria, so when you need antibiotics, they might not work.

Bacterial Infections

Common bacterial infections during pregnancy include urinary tract infections and group B strep. For such 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 illness could be more risky to your baby's health than exposing him to an antibiotic, according to Komal Bajaj, M.D., reproductive geneticist at Jacobi Medical Center.

Taking Antibiotics While Pregnant: Is It Safe?

"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 what antibiotic should be prescribed, as all antibiotics are different, Dr. Bajaj says.

While many medications have been found to be completely safe to take during pregnancy, others can cause serious birth abnormalities. The U. S. Food and Drug Administration (FDA)'s list of Pharmaceutical Pregnancy Categories help doctors (and their patients) know the prenatal safety of medications. The categories are A, B, C, D, and X. Drugs within Category A have been found to be safe for use in pregnant women, whereas drugs within Category X have been found to be harmful to fetuses and should not be used by pregnant women. If you are pregnant or are trying to become pregnant, ask your doctor about the pregnancy categories of any prescribed medications. You can also find the pregnancy category designation of each medication on its package insert.

Birth defects 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 defects, and cleft palate.

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 women to safely take Category B medications, such as Augmentin. The antibiotic is commonly used to treat bacterial infections such as sinusitis, pneumonia, and bronchitis, all which can be harmful to the baby if left untreated. The drug has undergone animal reproduction studies and appears to have no negative effect on the pregnancy, says. Aleksandr M. Fuks, M.D., Director of the Department of Obstetrics and Gynecology at Queens Hospital Center.

Penicillin, the most commonly used antibiotic during pregnancy, as well as other widely prescribed antibiotics, have not been found to be associated with increased risk for about 30 different birth defects, according to The National Birth Defects Prevention Study.

But ethical considerations preclude conducting drugs trials in pregnant women, so for many drugs, no adequate and well-controlled studies, Dr. Fuks says. There might be negative fetal effects associated with some Category B drugs that aren't currently recognized. "It should only be prescribed in situations where the healthcare 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 pencillin have been used safely for decades, resistant strains of bacteria are forcing doctors 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.

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

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Safe and Unsafe Antibiotics During Pregnancy

Some antibiotics commonly considered SAFE for use during pregnancy:

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

Some antibiotics commonly considered UNSAFE for use during pregnancy:

  • Bactrim
  • Ciprofloxacin
  • Doxycycline
  • Furadantin
  • Macrobid
  • Macrodantin
  • Minocycline
  • Septra
  • Tetracycline

[Note: These do not include all antibiotics considered safe or unsafe during pregnancy.]

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 macrolides – including azithromycin and clarithromycin – during pregnancy and having a baby with birth defects. Looking at data from over 135,000 pregnant women in the Quebec Pregnancy Cohort, they 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," 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, said. "This is reassuring when treating infections during pregnancy."

The FDA classifies azithromycin as a category B drug, which means it has been shown to be 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.

Talking to Your Doctor

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

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

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