Bibian van der Voorn

41 INTERPRETATION OF GC LEVELS IN NEONATAL HAIR in maternal hair. Age of the neonate at the OPV was negatively associated with hair cortisol, but not with cortisone levels (log-transformed β [95%CI]: cortisol -0.01 [-0.02 to -0.001], p=0.03; cortisone: 0.00 [-0.01 to 0.01], p=0.70). Age of the neonate at the OPV was not associated with delta cortisol or cortisone. TABLE 2. Concentrations of neonatal and maternal hair glucocorticoid concentrations Postpartum (median, range) n=107 Outpatient visit (median, range) n=72 P-value* Infant 169, 51 to 1294 71, 2 to 479 <0.001 85, 23 to 597 91, 30 to 346 0.99 Maternal 5, 0 to 672 4, 1 to 79 0.001 18, 2 to 87 18, 8 to 43 0.75 Values expressed as median, range in pg/mg. * Analyzed with a paired t-test, performed with log-transformed GC concentrations Correlations with maternal hair GCs Directly postpartum, maternal and neonatal hair cortisol were positively associated (n=107, r=0.336, β 0.23 [95%CI: 0.11 to 0.36], p<0.001), while no correlations were found betweenmaternal and infant hair cortisone (p=0.66). At the OPV, the association between maternal and infant hair cortisol was stronger than directly postpartum (n=71, r=0.457, β 0.41 [95%CI: 0.22 to 0.60], p<0.001), and no correlation was found for cortisone (p=0.12). Factors associated with neonatal hair GCs The effect of several perinatal and maternal factors on hair GC levels measured directly postpartum was studied ( Table 3 ). Gestational age was strongly associated with both cortisol and cortisone levels, as illustrated in Figure 1 , and this association remained significant when only term-born infants (n=98) were studied. Additionally, there was a positive association for both cortisol and cortisone levels with perinatal infection (defined as the need for treatment with antibiotics for ≥7 days). Birth weight was associated with both cortisol and cortisone when expressed in kilograms, but this association was lost when birth weight was expressed as the SD-score. Moreover, delivery via caesarian section was associated with both lower cortisol and cortisone levels, while multiparity was associated with lower cortisol levels. Next, the effect of the (borderline) significant factors on the course of GC levels was studied ( Table 4 ). Gestational age was associated with a trend toward a steeper decrease in cortisol and cortisone between birth and the OPV. Additionally, perinatal infection was associated with a steeper decrease in cortisone, while and delivery via cesarian section was associated with a smaller decrease in cortisone.