Bibian van der Voorn

43 INTERPRETATION OF GC LEVELS IN NEONATAL HAIR Finally, the effect of these factors on the GC levels at the OPV was analyzed ( Table 4 ). Gestational age was still positively associated with infant hair cortisol levels, but not with cortisone. Additionally, males had higher cortisol levels in hair at the OPV, but no association was found with cortisone. The other factors were not associated with OPV hair GC levels. TABLE 4. Associations of the course of neonatal hair GC concentrations with perinatal and maternal factors Effect on delta Effect on OPV values β (95%CI) P value β (95%CI) P value Perinatal factors Gestational age Cortisol -0.02 (-0.05 to 0.00) 0.08 0.08 (0.04 to 0.12) <0.001 Cortisone -0.006 (-0.013 to 0.001) 0.08 0.00 (-0.04 to 0.04) 0.87 Birth weight (kg) Cortisol -0.05 (-0.12 to 0.02) 0.19 0.13 (0.003 to 0.26) 0.05 Cortisone -0.02 (-0.03 to 0.01) 0.15 0.00 (-0.12 to 0.12) 0.96 Male sex Cortisol 0.02 (-0.07 to 0.11) 0.68 0.19 (0.02 to 0.36) 0.03 Cortisone -0.01 (-0.03 to 0.02) 0.46 0.00 (-0.14 to 0.13) 0.99 Delivery via caesarian section Cortisol 0.06 (-0.04 to 0.16) 0.24 -0.06 (-0.25 to 0.13) 0.55 Cortisone 0.03 (0.01 to 0.05) 0.02 -0.08 (-0.23 to 0.08) 0.33 Perinatal infection (≥7 days antibiotics) Cortisol -0.06 (-0.15 to 0.04) 0.25 -0.04 (-0.22 to 0.14) 0.66 Cortisone -0.03 (-0.05 to -0.004) 0.02 0.12 (-0.03 to 0.27) 0.11 Maternal factors Parity Cortisol 0.07 (-0.02 to 0.16) 0.11 -0.11 (-0.28 to 0.05) 0.18 Cortisone 0.01 (-0.01 to 0.03) 0.32 0.01 (-0.13 to 0.14) 0.91 Values represent log-transformed β (95% confidence interval) as calculated with linear regression. All associations were corrected for age at the OPV. DISCUSSION In this study, we have described the levels of cortisol and cortisone in neonatal hair, both directly postpartum, as well as at an OPV at 44±11 days postpartum. GC levels in neonatal hair directly postpartum seem to reflect intrauterine GC exposure, they are much higher than maternal levels and appear to be influenced mainly by gestational age, possibly reflecting the normal prenatal increase in endogenous fetal cortisol. After birth, cortisol levels decrease sharply, although at the OPV neonatal levels are still much higher compared to maternal levels. This suggests that at that time point GC levels represent both the intra- and extrauterine period, since GC levels in infants are not markedly different from maternal cortisol levels 22,23 . Additionally, at birth,