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

Short- and medium-chain fatty acids (SCFAs/MCFAs) modulate metabolic and inflammatory pathways. This study examined associations between maternal plasma SCFAs/MCFAs in the first (T1) and third (T3) trimesters and maternal and infant metabolic-inflammatory indices, maternal energy metabolism, and infant anthropometrics and body composition at 2 weeks and 6 months postpartum. Data were retrieved from the Growing Life, Optimizing Wellness Study. SCFAs/MCFAs were derivatized with 3-NPH and quantified by LC-MS in Time-of-Flight mass spectrometry with elevated energy mode., while metabolic-inflammatory indices were computed from standardized biomarkers (e.g., cholesterol, insulin, leptin). Sample sizes included up to 231 participants at T1, 156 at T3, 80 infants at 2 weeks, and 55 at 6 months. Generalized linear models adjusted for covariates and multiple comparisons. At T3, higher butyric, caproic, propionic, isobutyric, and isovaleric acids were linked to a lower maternal metabolic-inflammatory index, whereas higher acetate-to-propionate, acetate-to-butyrate, and propionate-to-butyrate ratios were linked to a higher index. Maternal acetic acid and total SCFA/MCFA concentrations were inversely associated with respiratory exchange ratio at T1 and T3. Limited associations were observed with infant indices or body composition. Overall, third-trimester SCFAs were associated with maternal metabolic-inflammatory pathways with minimal downstream infant effects.