A quick internet search reveals that many women rank giving birth as one of the most painful human experiences. Though pain can be hard to quantify objectively, the physiological stress of childbirth is clinically assessed by measuring blood levels of the stress hormone cortisol.
Cortisol is currently used to estimate the stress experienced by both mother and child during the process of giving birth, but recently published PLOS ONE research suggests that a different stress hormone, corticosterone, may be a more accurate way to measure the stress experienced by healthy, full-term babies.
For their study, researchers tested fetal levels of cortisol and corticosterone in 265 samples of umbilical cord blood from healthy deliveries. Though the total levels of cortisol detected were higher than corticosterone levels, fetuses produced the latter at a greater rate in response to the stress of labor and delivery. Newborns secreted more corticosterone when a Caesarian section was performed due to complications during labor than they did after a normal C-section. Fetal corticosterone levels were also higher after passage through the birth canal. These differences were not seen in levels of cortisol production. Based on these data, the authors suggest that the full-term fetus is more likely to secrete corticosterone than cortisol in response to stress and hence, corticosterone may be a more accurate clinical biomarker to assess fetal stress.
Corticosterone isn’t unheard of in the adult world, as adults continue to make the hormone throughout our lives, though in a much smaller proportion relative to cortisol. When babies switch to producing more cortisol rather than corticosterone isn’t yet clear, but the developmental changes involved may help track or diagnose adrenal gland functions in newborns.
Citation: Wynne-Edwards KE, Edwards HE, Hancock TM (2013) The Human Fetus Preferentially Secretes Corticosterone, Rather than Cortisol, in Response to Intra-Partum Stressors. PLoS ONE 8(6): e63684. doi:10.1371/journal.pone.0063684
Image: stress by topgold