R. Gitau et al., Fetal hypothalamic-pituitary-adrenal stress responses to invasive procedures are independent of maternal responses, J CLIN END, 86(1), 2001, pp. 104-109
Paired fetal and maternal samples were obtained, at fetal blood sampling an
d intrauterine transfusion, to study hypothalamic-pituitary-adrenal stress
responses. This confirmed that the fetus mounts an hypothalamic-pituitary-a
drenal stress response to transfusion via the intrahepatic vein, which invo
lves piercing the fetal trunk, but not to transfusion via the placental cor
d insertion [mean cortisol response via intrahepatic vein delta = 52.6 nmol
/L, 95% CI (25.3-79.9), P = 0.001; mean beta -endorphin response delta =106
pg/mL, 95% CI (45.3-167), P = 0.002]. Baseline maternal fetal ratios were
13 [95% CI (10.1-15.2)] for cortisol and 0.8 [95% CI (0.5-1.0)] for beta -e
ndorphin. The novel findings were: 1) that the fetal responses mere indepen
dent of those of the mother, which did not change during transfusion at eit
her site; 2) that there was a correlation between baseline fetal and matern
al cortisol levels (r = 0.58, n = 51, P < 0.0001) but not between baseline
fetal and maternal <beta>-endorphin levels, suggesting cortisol transfer ac
ross the placenta, rather than joint control by placental CRH; and 3) that
fetal beta -endorphin responses were apparent from 18 weeks gestation and i
ndependent of gestational age, whereas fetal cortisol responses were appare
nt from 20 weeks gestation and were dependent on gestational age (y = -91.4
+ 5.08 x, r = 0.51; n = 16; P = 0.04; CI for slope, 0.16-10.0), consistent
with the maturation of the fetal pituitary before the fetal adrenal.