Plasma carnitine levels of pregnant adolescents in labor

Study objective: To determine the concentration of plasma carnitine (total, free, and acylcarnitine) during the delivery of uncomplicated pregnancies of adolescent women. To investigate the relationship between maternal and neonatal levels of carnitine and to compare these carnitine levels between pregnant and nonpregnant adolescents.

Design: Samples of maternal and umbilical blood were taken at the time of delivery and examined for the determination of the carnitine-total, free, and acylcarnitine-concentration by the use of an enzymatic-radioisotope method. Twenty-two cases of uncomplicated adolescent pregnancies with a normal labor and without perinatal complications were examined. The plasma level of carnitine was also examined in 17 healthy nonpregnant adolescent women, which constituted the control group.

Results: The concentrations of plasma carnitine in adolescent pregnancies at the time of delivery were calculated at 19.6 +/- 2.15 microMol/L (total), 12.62 +/- 1.31 microMol/L (free), and 6.98 +/- 1.55 microMol/L (acylcarnitine). The corresponding mean values in umbilical plasma were 30.31 +/- 2.06 microMol/L, 22.39 +/- 1.64 microMol/L, and 7.92 +/-.96 mucroMol/L. There is a statistically significant difference between the mean values in maternal and umbilical plasma (P <.0001 for total and free carnitine and P <.012 for acylcarnitine). The correlations between adolescent pregnant women and their infants as regards total, free, and acylcarnitine were 0.137, 0.018, and 0.33, respectively. Neither of these parameters was statistically significant. The corresponding mean values of carnitine in nonpregnant adolescent women were statistically significantly higher than in adolescent pregnant women (total carnitine: 41.61 +/- 3.09 microMol/L, free: 31.39 +/- 2.81 microMol/L, acylcarnitine: 10.22 +/- 1.88 microMol/L, P <.0001).

Conclusions: The concentration of plasma carnitine at the end of adolescent pregnancy is low compared to the levels of umbilical carnitine at birth and that found in nonpregnant adolescent women. It may not have an obvious impact on the utilization of fatty acids in an uncomplicated full-term pregnancy; however, it suggests the potential risk for neonatal fatty-acid oxidation in a preterm or complicated pregnancy.