# Maternal red blood cell folate metabolites were dynamically associated with neonatal amino acids and acylcarnitines in heel blood: a prospective cohort study

## TL;DR

This study found that specific maternal folate metabolites, especially THF, are linked to neonatal amino acids and fatty acid metabolism in a trimester-specific way.

## Contribution

The study reveals trimester-specific associations between maternal folate metabolites and neonatal metabolic profiles, which is novel in human cohort research.

## Key findings

- THF levels increased continuously during pregnancy and were associated with neonatal amino acids and acylcarnitines.
- THF in early pregnancy positively correlated with phenylalanine and tyrosine metabolism and fatty acid β-oxidation.
- UMFA levels declined throughout pregnancy and showed weaker, trimester-specific associations with neonatal metabolism.

## Abstract

Animal studies indicate maternal folic acid intake alters offspring amino acids (AAs) and fatty acid profiles, affecting their long-term health. However, human data on specific folate metabolites remain limited. We explored their dynamic associations with neonatal AAs and acylcarnitines (ACs).

We conducted a prospective cohort study, involving 4130 singleton pregnant women and their neonates. Maternal total folate and related metabolites in red blood cell (RBC), including 5‐methyltetrahydrofolate (5‐MTHF), tetrahydrofolate (THF), 5‐formyltetrahydrofolate (5‐CHO‐THF), and unmetabolized folic acid (UMFA), were measured in 6–17 (T1), 20–26 (T2), and 32–36 (T3) gestational weeks. Neonatal metabolites, including 11 AAs and 31 ACs, were routinely tested 72 h postpartum using heel blood samples. Linear regression and pathway analysis were used to evaluate associations between maternal folate metabolites with neonatal metabolic pathways.

5-MTHF and total folate levels significantly increased from T1 to T2 (p < 0.001), and stabilized from T2 to T3 (p > 0.05). THF and 5-CHO-THF levels showed a continuous upward trend (p < 0.001). Conversely, UMFA declined throughout pregnancy (p < 0.001). Total folate and 5-MTHF showed no significant correlations with neonatal metabolism. THF were associated with multiple neonatal metabolites, and the associations peaked in T1 and declined in T2 and T3. THF in T1 positively correlated with phenylalanine and tyrosine, involved in the phenylalanine and tyrosine metabolism. And it was positively associated with 7 ACs and negatively with 9 ACs, involved in the fatty acids β-oxidation. THF in T2 or T3 positively related to arginine, and negatively with citrulline, glycine, and ornithine, involved in the urea cycle and arginine and proline metabolism. 5-CHO-THF displayed similar and weaker impacts, correlated with fatty acids β-oxidation only in T1. UMFA exhibited different and weaker influence, related to the urea cycle, arginine and proline metabolism only in T1.

Although maternal total folate and 5-MTHF levels showed no significant association with neonatal metabolites, maternal certain folate metabolites, especially THF, exhibited trimester-specific associations with neonatal metabolic pathways, warranting clinical attention.

The online version contains supplementary material available at 10.1186/s12986-025-01064-2.