Circulating short- and medium-chain fatty acids in pregnancy and associations with maternal and infant metabolism, inflammation, and body composition.

At third trimester, higher concentrations of butyric, caproic, propionic, isobutyric, and isovaleric acids were associated with a lower maternal metabolic-inflammatory index.

• Associations were observed in the third trimester (T3) but not consistently in the first trimester (T1).
• Generalized linear models were adjusted for covariates and multiple comparisons.
• Sample size at T3 included up to 156 participants.
• The metabolic-inflammatory index was computed from standardized biomarkers including cholesterol, insulin, and leptin.

Higher acetate-to-propionate, acetate-to-butyrate, and propionate-to-butyrate ratios in the third trimester were associated with a higher maternal metabolic-inflammatory index.

• These ratio associations were directionally opposite to those of individual SCFAs such as butyric and propionic acids.
• Findings were from T3 analyses with up to 156 participants.
• Models were adjusted for covariates and multiple comparisons.
• This suggests that SCFA ratios, not just absolute concentrations, may be relevant to maternal metabolic-inflammatory status.

Maternal acetic acid and total SCFA/MCFA concentrations were inversely associated with respiratory exchange ratio at both first and third trimesters.

• The inverse association with respiratory exchange ratio was observed at both T1 (up to 231 participants) and T3 (up to 156 participants).
• A lower respiratory exchange ratio indicates relatively greater fat oxidation compared to carbohydrate oxidation.
• SCFAs/MCFAs were quantified using LC-MS in Time-of-Flight mass spectrometry with elevated energy mode after derivatization with 3-NPH.
• These associations suggest a link between circulating SCFAs and maternal energy metabolism across pregnancy.

Circulating maternal SCFAs/MCFAs showed limited associations with infant metabolic-inflammatory indices and body composition at 2 weeks and 6 months postpartum.

• Sample sizes for infant outcomes included up to 80 infants at 2 weeks and 55 infants at 6 months postpartum.
• Infant anthropometrics and body composition were assessed at both 2 weeks and 6 months postpartum.
• The paper concludes there were 'minimal downstream infant effects' from maternal SCFA/MCFA levels.
• Both infant metabolic-inflammatory indices and body composition measures were examined.

The study used a derivatization-based LC-MS method to quantify plasma SCFAs and MCFAs across two trimesters of pregnancy.

• SCFAs/MCFAs were derivatized with 3-nitrophenylhydrazine (3-NPH) and quantified by LC-MS in Time-of-Flight mass spectrometry with elevated energy mode.
• Data were retrieved from the Growing Life, Optimizing Wellness Study.
• Sample sizes included up to 231 participants at T1 and 156 at T3.
• Individual fatty acids measured included acetic, propionic, butyric, isobutyric, isovaleric, and caproic acids, among others.

Short- and medium-chain fatty acids modulate metabolic and inflammatory pathways, providing rationale for examining their role during pregnancy.

• SCFAs and MCFAs were selected as exposures of interest due to their known roles in modulating metabolic and inflammatory pathways.
• Both first and third trimester time points were examined to capture changes across pregnancy.
• The study examined associations with maternal energy metabolism as well as metabolic-inflammatory indices.
• The Growing Life, Optimizing Wellness Study provided the longitudinal dataset for this analysis.