Determination of carnitine ester patterns during the second half of pregnancy, at delivery, and in neonatal cord blood by tandem mass spectrometry: complex and dynamic involvement of carnitine in the intermediary metabolism.

We studied plasma concentrations of free carnitine and 30 carnitine esters by electron spray ionization (ESI) tandem mass spectrometry in 37 pregnant women at the 20th and 30th weeks of gestation and at delivery, and in their neonates at birth, and in 22 age-matched nonpregnant women. The plasma levels of acetylcarnitine and carnitine esters with more than five carbons were significantly higher, whereas the concentration of free carnitine was significantly lower at term than at the 20th week of pregnancy (16.75 +/- 0.89 versus 19.61 +/- 1.25). Almost all of C2- to C12-carnitine esters were significantly lower, whereas C16- and C18-carnitines with in-chain modifications were significantly higher in mothers at delivery compared with nonpregnant women. Plasma levels of free carnitine and C2-, C3-, C4-, C5-, C6-, and C16-carnitines were significantly lower, while concentrations of carnitine esters with 8, 10, 12 and 18 carbons in the acyl chain as well as C14:1-, C14:2-, and C16:1-OH-carnitines were significantly higher in mothers at term than in their neonates. The data of the present study clearly show dynamic features of plasma carnitine profile during pregnancy and indicate an extraordinarily active participation of the carnitine in the intermediary metabolism both in the pregnant woman and in the neonate.