The most common bacterial infections during pregnancy include urinary tract infections, cellulitis and skin
abscesses, upper and lower respiratory tract infections, and sexually transmitted diseases. Management of
bacterial infections in pregnant women requires early antimicrobial treatment to prevent adverse maternal and
pregnancy outcomes. As such, antibiotics are among the most commonly used medications in pregnancy –
approximately six out of ten publicly insured and four out of ten commercially insured pregnant women fill at
least one antibiotic prescription during pregnancy.
To select the optimal antibiotic from the range of available options for specific infections, it is therefore crucial
to understand the comparative safety of in utero exposure to specific antibiotics. Unfortunately, rigorous and
comprehensive safety data to inform the risk-benefit trade-off are sparse and evidence is conflicting. The
primary concern among potential risks associated with antibiotic use in pregnancy are congenital
malformations, which are a leading cause of neonatal morbidity and mortality, and frequently cause lifelong
disability. Additionally, some studies have pointed to an increased risk of spontaneous abortions and neonatal
jaundice associated with some commonly used classes of antibiotics. Given that 45% of pregnancies in the US
are unintended, understanding the comparative safety of antibiotics in early pregnancy may also inform the
selection of antibiotics in women of reproductive age.
The objective of the proposed studies is therefore to evaluate the comparative safety of antibiotics commonly
used for the treatment of bacterial infections during pregnancy. To accomplish this, we will employ large
pregnancy cohorts of publicly and privately insured pregnant women (N ≈ 4.5 million). For each of the most
common bacterial infections, we will assess the comparative safety of available commonly used antibiotic
treatment options and utilize the rich information in our data sources to control for potential confounding
variables. The large study size will enable quantification of effects for the pre-specified outcomes (i.e.,
malformations overall, specific malformation types, spontaneous abortion, and neonatal jaundice) with great
precision. In addition, to ensure a comprehensive evaluation of the comparative safety, we will utilize a novel
signal detection method developed by members of our team, TreeScan, for simultaneous evaluation of a broad
range of potential maternal, fetal and neonatal adverse outcomes.
By harnessing the power of existing real-world data, this study will inform strategies for tailoring antibiotic
treatment to optimize pregnancy outcomes in this vulnerable population. As such, the proposed study aligns
well with the main goal of PAR-20-300. By defining the safest treatment options for women of reproductive age
with bacterial infections, the findings of this study will have direct and immediate clinical impact.