New Study Explores Link Between Antibiotic Use and Psychological Distress in Pregnant Women

Perinatal depression is a common mental health condition affecting women during pregnancy or post-childbirth, impacting maternal well-being and child development. Emerging evidence suggests a potential link between antibiotic use and maternal mental health.

A recent study, published on January 10, 2026, in BMC Public Health, investigated this potential connection. Researchers Kenta Matsumura and Hidekuni Inadera led the investigation into the association between antibiotic use and psychological distress in pregnant women.

Study Methodology

The study leveraged data from a large cohort to examine the intricate relationship between antibiotic exposure and maternal mental health.

• Participants: The analysis included data from 94,490 pregnant women enrolled in the Japan Environment and Children's Study (JECS). Participants were typically around 12 weeks pregnant, with follow-up conducted at approximately 15 weeks.

• Antibiotic Use Data: Information was meticulously collected on antibiotic use during two key periods: the year prior to early pregnancy (covering before conception until pregnancy recognition) and from pregnancy recognition until study enrollment.

• Categorization: Participants were systematically grouped based on their antibiotic use: those with no use, those who used antibiotics during one of the two specified periods, or those who used them during both periods.

• Psychological Distress Assessment: Psychological distress was assessed using the Japanese version of the Kessler Psychological Distress Scale (K6), a validated six-item self-reported questionnaire.

• Statistical Analysis: To ensure robust findings, adjusted odds ratios were calculated. These compared antibiotic users to the non-antibiotic use group, while carefully accounting for various confounding factors such as maternal age, BMI, education, income, smoking, alcohol use, marital status, and psychiatric history.

Key Findings

The study revealed a notable association between antibiotic use and psychological distress, particularly as exposure increased.

Antibiotic use before and during pregnancy showed an association with psychological distress in early- to mid-pregnancy, displaying a stepwise pattern.

• For moderate psychological distress (defined by a K6 score of 5 to 12):

  • The adjusted odds ratio was 1.12 for women who used antibiotics during one period.
  • The adjusted odds ratio increased to 1.22 for those who used antibiotics during both periods, compared to the group with no antibiotic use.

• For severe psychological distress (defined by a K6 score greater than 13):

  • The adjusted odds ratio was 1.07 for use during one period.
  • Significantly, this ratio rose to 1.50 for use during both periods, compared to no antibiotic use.

Higher odds ratios correlated with increased antibiotic exposure, indicating a greater likelihood of experiencing psychological distress. This suggests a dose-response relationship where more frequent or prolonged antibiotic use may heighten the risk.

Potential Explanations and Implications

Researchers propose that alterations in gut microbiota caused by antibiotics could be a contributing factor to psychological distress. Changes in gut microbiota have previously been linked to various health conditions, including psychiatric conditions, highlighting a plausible biological pathway.

The study emphasizes that these findings do not advise against medically necessary antibiotic use. Instead, they contribute to crucial discussions regarding appropriate antibiotic prescriptions.

The researchers suggest that increasing awareness about avoiding unnecessary antibiotic use, such as for common colds, may be particularly relevant for supporting maternal mental health during pregnancy. This highlights a need for judicious prescribing practices and patient education.