# Sex differences in the blood metabolome of extremely preterm infants: a pilot study on the impact of antibiotic therapy

## TL;DR

This study shows that antibiotic treatments affect the metabolism of extremely premature babies differently depending on their sex, with males showing more significant changes.

## Contribution

The study reveals sex-dependent metabolic effects of antibiotic therapy in extremely preterm infants, a previously underexplored area.

## Key findings

- Untreated male and female infants had similar metabolomic profiles, except for higher C16OH in males.
- Antibiotic treatment amplified sex differences, with males showing significantly elevated acylcarnitine levels.
- Female infants showed more stable metabolic profiles and were less affected by antibiotic therapy.

## Abstract

Despite growing recognition of sex differences in medicine, little is known about their role in neonatology, particularly among extremely premature infants (EPI, < 28 weeks gestation), who face high morbidity and mortality driven by infections. Antibiotics therapy is widely used but may alter cellular metabolism, leading to adverse drug reactions. However, pharmacological studies in EPI remain limited, and sex-dependent effects of antibiotic treatments are largely unexplored. This study investigated sex-related metabolomic differences in EPI in relation to antibiotic exposure.

Targeted mass spectrometry (MS) was applied to dried blood spots (DBS) collected within the neonatal screening program of the Campania region (Italy) between 2018 and 2023. Amino acids (AA) and acylcarnitines (AC) were quantified in 116 EPI stratified by sex and antibiotics treatment.

Untreated EPI of both sexes showed largely comparable metabolic profiles, with the exception of higher C16OH levels in males. Antibiotic treatment, however, markedly amplified sex-dependent divergence, with male EPI displaying significantly elevated AC concentrations (C0, C2, C3, C4, C5, C6, C5OH, C10:1, C16:1, C18, C18:1) compared to females. Stratification by penicillins + aminoglycosides treatment revealed distinct patterns: in EPI treated with a penicillins + aminoglycosides combination, males exhibited higher levels of C0, C2, C4, C6, C16:1, C18, and C18:1, while C3, C5, C5OH, and C10:1 no longer differed by sex. Furthermore, eight additional AC (C3DC, C14:1, C14, C16, C10DC, C16OH, C4OH, C16:1OH) were significantly elevated in treated males, differences that were not detected when all antibiotic classes were pooled.

These findings demonstrate that standard empirical antibiotic therapies for prematurity exert sex-dependent effects on neonatal metabolism, with antibiotics amplifying AC alterations in males. Our results underscore the need to consider sex as a key biological variable in neonatal pharmaco-metabolomics and highlight the potential of metabolic profiling to optimize individualized treatments in EPI.

The online version contains supplementary material available at 10.1186/s13293-025-00798-1.

Babies born extremely early, before 28 weeks of pregnancy, face many health challenges. They are very vulnerable and often need treatments like antibiotics to fight infections. In this study, we looked at tiny blood samples obtained from 116 very premature babies in the Campania region of Italy, collected between 2018 and 2023. We wanted to see if males and females responded differently to these common treatments. We found that when babies were not treated with antibiotics, males and females had very similar blood patterns. However, when antibiotics were given, males showed stronger changes in the way their bodies handled acylcarnitines, considered indirect indicators of mitochondrial function, and amino acids, which could signal a difference in how they process energy. These results show that antibiotic treatment can affect premature babies in different ways depending on whether they are males or females. This highlights the need for doctors and researchers to consider sex differences when caring for and studying premature newborns. By better understanding these differences, we can work toward safer, more personalized care for the most vulnerable babies.

The online version contains supplementary material available at 10.1186/s13293-025-00798-1.

Sex impacts on the metabolome of extremely premature infants (EPI) under real-world clinical antibiotics treatment.Antibiotic therapy triggers significant metabolic alterations in male EPI but has a scarce effect in female EPI.Sex-related differences are more pronounced in EPI infants treated with penicillins + aminoglycosides, especially in males.Female EPI showed more stable metabolic profiles and were less sensitive to pharmacological treatment.These findings emphasize the importance of sex awareness in neonatal care.

Sex impacts on the metabolome of extremely premature infants (EPI) under real-world clinical antibiotics treatment.

Antibiotic therapy triggers significant metabolic alterations in male EPI but has a scarce effect in female EPI.

Sex-related differences are more pronounced in EPI infants treated with penicillins + aminoglycosides, especially in males.

Female EPI showed more stable metabolic profiles and were less sensitive to pharmacological treatment.

These findings emphasize the importance of sex awareness in neonatal care.

The online version contains supplementary material available at 10.1186/s13293-025-00798-1.