Table 1.
Median concentration and range for corticosterone and cortisol (ng/ml) in all samples, and samples stratified by mode of delivery.
Figure 1.
Fetal corticosteroid synthesis.
Proportional change in corticosteroid concentrations after passage through the fetus ([A-V]/V) for 265 paired umbilical cord samples. Values near or below zero will include human error accidentally mixing arterial with venous blood during sampling. A value of 1.0 represents a 100% increase, or doubling, of the concentration of corticosteroid from the umbilical vein to the umbilical artery. As the data are intrinsically paired within individuals, statistical comparisons are not shown.
Figure 2.
Association between fetal corticosterone and cortisol synthesis by delivery type.
Proportional change in corticosteroid concentrations after passage through the fetus ([A-V]/V) for 163 vaginal deliveries (Vag: open circles), 53 scheduled Caesarian sections (C: solid circles), and 49 Emergent C-sections (EC: shaded triangles). Linear positive association, and range of response, are reported in the text.
Figure 3.
Absolute corticosteroid synthesis differences by delivery type.
Absolute increase [A-V] ng/ml in concentration after passage of the fetus for corticosterone (panel a) and cortisol (panel b) across the three types of delivery: scheduled and emergent Caesarian sections (C, EC) and vaginal deliveries (Vag). Letters that differ indicate a significant post-hoc difference between groups following an overall effect of delivery type.
Figure 4.
Maternal regional analgesia increases absolute fetal glucocorticoid synthesis.
For vaginal deliveries only (Vag), absolute increase [A-V] ng/ml in concentration after passage of the fetus for corticosterone (panel a) and cortisol (panel b) in the absence (N = 46) or presence (N = 117) of regional maternal analgesia (i.e. epidural). The asterisk indicates a significant increase in corticosteroid synthesis in the presence of maternal analgesia.
Figure 5.
Fetal stress increases fetal corticosterone, but not cortisol, synthesis.
For emergent C-sections only (EC: N = 49), absolute increase [A-V] ng/ml in concentration after passage of the fetus for corticosterone (panel a) and cortisol (panel b) in groups stratified by the clinical rationale for the emergent C-section: fetal heart rate abnormalities (FHR: N = 11); Failure to progress in stage 1 (FTP1: N = 19), and failure to progress in Stage 2, representing cephalo-pelvic disproportion detected after a history of labor (FTP2: N = 14). Five EC cases were excluded because the chart record was not clear on the rationale for EC. Letters that differ indicate a significant post-hoc difference between groups, with FTP2 corticosterone higher than FHR and FTP1, following an overall effect of rationale for EC.G.
Figure 6.
Schematic illustration of changes in median corticosteroid concentrations.
Relative concentrations of corticosterone and cortisol in umbilical artery and vein, showing preferential fetal synthesis of corticosterone coupled to placental inactivation of corticosteroids.