When a pregnant woman develops an infection, her treatment involves two patients—herself and her developing baby—requiring careful consideration of every medication decision.
When a pregnant woman develops a urinary tract infection or other bacterial infection, her doctor faces a complex challenge. The antibiotics that could safely treat her before pregnancy now carry additional considerations. Some medications might affect the developing fetus differently depending on the pregnancy stage, while others might be processed differently by her changing body. This delicate balancing act between effectively treating infections and ensuring fetal safety makes the use of anti-infective drugs in obstetrics one of medicine's most nuanced practices.
Untreated infections can lead to serious complications for the mother, including sepsis and organ damage.
Medication exposure during critical developmental periods can impact fetal growth and organ formation.
Clinicians must weigh the risks of medication against the dangers of untreated infection.
For decades, doctors relied on a simple A, B, C, D, X pregnancy category system to quickly assess medication risks during pregnancy. However, in 2018, the U.S. Food and Drug Administration replaced this system with more detailed narrative information in the Pregnancy and Lactation Labeling Rule (PLLR)1 .
The updated labels now provide comprehensive details in three key areas1 :
This shift recognizes that medication safety in pregnancy isn't always black and white but often involves careful risk-benefit analysis. This is particularly true for antibiotics, which account for nearly 80% of all prescription medications during pregnancy1 .
Antibiotics account for nearly 80% of all prescription medications during pregnancy1 .
The decision to prescribe antibiotics during pregnancy involves weighing the very real dangers of untreated infection against potential medication risks. Infections like urinary tract infections and sexually transmitted infections can lead to serious complications including vertical transmission to the fetus, low birth weight, preterm birth, and premature fetal membrane rupture1 .
A 2022 population-based study highlighted this complexity, finding that while antibiotic use during pregnancy was associated with a slightly increased risk of preterm birth, this risk was significantly higher in women with comorbidities like diabetes and hypertension1 . This suggests that underlying health conditions may influence how medications affect pregnancy outcomes.
Fortunately, several antibiotic classes have established safety profiles in pregnancy:
These medications remain the first-line treatments for most common bacterial infections during pregnancy, including urinary tract infections, respiratory infections, and skin and soft tissue infections1 .
| Antibiotic Class | Safety Rating | Key Concerns | Clinical Guidance |
|---|---|---|---|
| Penicillins | Generally Safe | Minimal concerns | First-line for many infections |
| Cephalosporins | Generally Safe | Minimal concerns | First-line for many infections |
| Aminoglycosides | Use with Caution | Ototoxicity (especially streptomycin) | Short courses only if benefits outweigh risks |
| Fluoroquinolones | Avoid | Renal toxicity, cardiac defects | Use only if no alternatives |
| Macrolides | Use with Extreme Caution | Spontaneous abortion, birth defects | Reserve for specific indications |
Since 2014, 19 new antibiotics have received FDA approval, creating additional decision points for clinicians1 . For example, plazomicin, approved in 2018 for complicated UTIs, carries similar fetal warnings as other aminoglycosides despite no published human pregnancy safety data1 .
A recent multiregional study in Italy provided valuable insights into how antibiotics are actually used during pregnancy3 . The research analyzed data from 449,012 women who gave birth between 2016 and 2018, offering one of the most comprehensive pictures of real-world antibiotic prescribing patterns.
Researchers divided the analysis period into nine trimesters: three before pregnancy, three during pregnancy, and three after delivery3 . For each woman, they3 :
The study revealed that antibiotic use was common throughout the pregnancy journey3 :
Significant regional variations emerged, with Lombardy and Veneto having the lowest usage rates during pregnancy (26.1% and 26.4% respectively), while Apulia reached the highest values at 41.6%3 . These disparities highlight how prescribing practices can vary based on local protocols and possibly differing interpretation of safety evidence.
The research also uncovered a telling pattern related to invasive prenatal diagnostic procedures. Women undergoing chorionic villus sampling showed a peak antibiotic usage of 25% during the first trimester, while those having amniocentesis reached 41% during the second trimester—directly corresponding to the timing of these procedures3 . This is particularly noteworthy since current guidelines do not recommend antibiotic prophylaxis for these procedures, suggesting potential overprescribing3 .
Maternal sepsis—a life-threatening organ dysfunction caused by infection—represents one of the most urgent obstetric scenarios requiring anti-infective drugs7 . Sepsis is the third leading cause of maternal mortality globally, responsible for 11% of maternal deaths7 .
Pregnancy creates unique challenges for sepsis diagnosis and treatment7 :
Common pathogens in maternal sepsis include:
The treatment approach emphasizes speed: empiric broad-spectrum antibiotics should be initiated within one hour of recognition of possible sepsis, with therapy tailored once specific pathogens are identified7 .
| Research Tool | Primary Function | Application Example |
|---|---|---|
| Healthcare Databases | Track prescription patterns | Analyzing regional antibiotic use variations3 |
| Pregnancy Registries | Collect safety data | Post-marketing surveillance of new antibiotics1 |
| Laboratory Parameter Monitoring | Assess organ dysfunction | SOFA scores for sepsis diagnosis7 |
| Culture and Sensitivity Testing | Identify pathogens and resistance | Tailoring antibiotic therapy for maternal sepsis7 |
Recent innovations are beginning to shape the future of infectious disease management in obstetrics and gynecology:
Gepotidacin, approved by the FDA in March 2025, represents the first new oral antibiotic class in over 20 years for uncomplicated urinary tract infections5 . Its novel mechanism offers hope against resistant infections.
New at-home testing options for sexually transmitted infections may lead to earlier detection and treatment5 .
The journey of anti-infective use in pregnancy illustrates a fundamental principle in obstetric care: sometimes, protecting two patients requires not just choosing between options, but carefully navigating the delicate space between them.
As research continues, the goal remains finding that precise balance—effectively treating maternal infections while safeguarding fetal development. With antibiotic resistance increasing and new pathogens emerging, this field will continue to demand careful attention from researchers and clinicians alike.