Antibiotics are powerful medications that fight infections by killing bacteria or preventing them from growing and reproducing. While sometimes essential during pregnancy, labor, or postpartum, they can have unintended side effects. Although they can be life-saving, antibiotic use, overuse, and misuse is a growing public health concern due to antibiotic resistance—when bacteria adapt and become harder to treat. 

Antibiotics can also affect your and your baby’s microbiome—the balance of beneficial bacteria in your gut, on your skin, and even in your breastmilk. These bacteria play an important role in digestion, immune function, and overall health. Talking with your healthcare provider about the real risks and benefits helps you make informed decisions that prioritize your own health and your baby’s well-being, especially as you begin breastfeeding. For these reasons, they should only be used when truly necessary.

When Antibiotics May Be Recommended

Antibiotics may be recommended in certain situations, including:

Group B Streptococcus (GBS)

A common bacteria in the gastrointestinal and genital tracts. Usually harmless to adults, but can be risky for babies during childbirth. Testing usually occurs between 36–37 weeks of pregnancy, and IV antibiotics may be given during labor to protect your baby from infection.

Preterm Labor

If labor begins before 37 weeks and infection is suspected, antibiotics may help treat the infection and slow labor if appropriate.

Ruptured Membranes

If your water breaks early or is prolonged (over 18–24 hours), antibiotics may help prevent infection for both you and your baby.

Maternal Infections Unrelated to Pregnancy

Antibiotics may be used for infections like urinary tract infections, sinus infections, or for dental procedures that occur during pregnancy or after your baby's birth to protect your health and reduce complications.

Infections During Labor and Postpartum

Fever during labor or infections such as mastitis after birth may require medication to protect both mother and baby.

Cesarean Birth

IV antibiotics are routinely given during cesarean deliveries or other surgical procedures to prevent infection.

How These Medications Can Affect Mom and Baby

While these infection-fighting treatments are often essential for managing or preventing infections, they can have unintended effects, especially around childbirth and breastfeeding.

Effects on Your Baby

  • Microbiome Changes: Antibiotics can cross the placenta, be present in breast milk, or pass via skin contact, potentially altering the infant microbiome. This may affect your baby’s gut health, immune function (including allergies), and overall health.

  • Candida Infections and Thrush: Newborns may develop white patches in the mouth, on the lips, tongue, or a red, painful diaper rash. Coordinated care between your healthcare provider and your baby’s pediatrician is important to ensure both mom and baby are treated effectively.

Effects on Mom

  • Side effects: Common side effects include stomach upset, diarrhea, allergic reactions, and, rarely, changes in heart rhythm.

  • Fungal Infections: Antibiotic use increases the risk of vaginal yeast infections (an overgrowth of candida albicans) and thrush in breastfeeding mothers. Sudden nipple pain, redness, itchiness, or burning warrants a lactation consultation.

  • Milk Supply: Most infection-fighting medications are considered compatible with breastfeeding and don’t directly reduce milk supply. However, some mothers may notice a temporary dip if they’re recovering from illness, feeling fatigued, or dehydrated. Supporting your recovery with rest, fluids, and frequent milk removal can help maintain your supply while you heal.

According to the American Academy of Pediatrics, many antibiotics are compatible with breastfeeding, but they should only be used under medical guidance and when truly necessary.

What Can You Do to Reduce the Risks of Antibiotics?

Even when necessary, there are steps you can take to protect your, and your baby’s microbiome and support breastfeeding:

Support Breastfeeding and Bonding

  • Breastfeed When Possible: Human milk contains antibodies, healthy bacteria, and nutrients that support infant health and your baby’s microbiome.

  • Skin-to-Skin Contact: Holding your baby immediately after birth helps transfer beneficial bacteria and supports frequent breastfeeding in the early days.

Support Your Microbiome Through Diet and Supplements

  • Eat Prebiotics and Probiotics: Foods like yogurt, kefir, and fiber-rich fruits and vegetables promote healthy gut bacteria in both mom and baby.

  • Consider Supplements: Vitamins C and D may help support your immune system. Some research also suggests that probiotic supplementation during the last trimester of pregnancy may reduce the likelihood of testing positive for Group B Strep at 36–37 weeks.

Minimize Antibiotic Impact

  • Consider Duration and Dosage: Using antibiotics for the shortest effective period helps minimize disruption to microbiomes while still effectively treating infections.

  • Choose a Safe Alternative When Possible: When available, your healthcare provider may recommend narrow-spectrum options or other safer alternatives to reduce risks. Always weigh the benefits of treating infections against potential adverse effects for both you and your baby.

The use of antibiotics can play an important role in protecting both you and your baby from infections, and many are compatible with breastfeeding when used appropriately. Understanding the potential effects on your microbiome, your baby’s health, and breastfeeding can help you make informed choices. By working closely with your healthcare provider, practicing strategies like breastfeeding, skin-to-skin contact, and supporting gut health through diet or supplements, you can minimize risks while giving your baby the best possible start.

Disclaimer: Our classes and accompanying materials are intended for general education purposes and should not replace medical advice. For personalized recommendations, please consult your healthcare provider and/or lactation consultant.