Full-term deliveries without antecedent labor reveal sex differences in umbilical cord glucocorticoid concentrations.
Previous studies have shown that pregnant women have higher salivary cortisol levels when the fetus is female. These findings suggest a basis for the sex differences observed in many offspring outcomes after exposure to in utero stress, but it is not known if fetal adrenal glucocorticoid synthesis differs by sex.



Arterial and venous umbilical cord blood samples were collected immediately after scheduled cesarean delivery (n=52, 25 female). Cortisol and corticosterone concentrations were quantified by liquid chromatography coupled to tandem mass spectrometry.



Sex differences were observed for fetal arterial and venous cortisol and venous corticosterone, with higher levels present when the fetus was female. However, sex differences were not observed for fetal synthesis of cortisol, suggesting that the fetus does not control the differences observed in cord blood glucocorticoids.



The presence of sex differences in umbilical cord glucocorticoid concentrations in the absence of sex differences in glucocorticoid synthesis by the fetal adrenal gland suggests that these differences have a maternal or placental origin. Thus, the in utero glucocorticoids in circulation are sex-specific and may have developmental importance for sex differences in psychiatric and neurodevelopment disorders that display sex biases.
Department of Pediatrics, University of Calgary, 2500 University Drive N.W., Calgary, AB T2N 1N4, Canada; Department of Community Health Sciences, University of Calgary, 2500 University Drive N.W., Calgary, AB T2N 1N4, Canada; Alberta Children's Hospital Research Institute, University of Calgary, 2500 University Drive N.W., Calgary, AB T2N 1N4, Canada; Department of Psychology, University of Calgary, 2500 University Drive N.W., Calgary, AB T2N 1N4, Canada. Electronic address: ggiesbre@ucalgary.ca.
Gerald F
GF
Giesbrecht
Department of Psychology, University of Calgary, 2500 University Drive N.W., Calgary, AB T2N 1N4, Canada.
Joshua A
JA
Rash
Allan Centre for Women & Department of Obstetrics and Gynecology, University of Calgary, Calgary, Alberta, Canada.
Heather E
HE
Edwards
Comparative Biology & Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive N.W., Calgary, AB T2N 4N1, Canada; Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive N.W., Calgary, AB T2N 4N1, Canada.
Katherine E
KE
Wynne-Edwards
D002585:Cesarean Section; D003345:Corticosterone / Q000378:metabolism*; D005260:Female; D005312:Fetal Blood / Q000378:metabolism*; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D007231:Infant, Newborn; D008297:Male; D012737:Sex Factors; D014469:Umbilical Arteries / Q000378:metabolism*; D014471:Umbilical Veins / Q000378:metabolism*
D003345:Corticosterone; D006854:Hydrocortisone
Cesarean delivery; Cord blood; Corticosterone; Cortisol; Sex differences