β-Endorphin concentration in colostrums of Burkinabe and Sicilian women

Objective Endorphins (EPs) present in human colostrum may be relevant for immediate postnatal fetal adaptation because this compound is involved in stress response and adaptation mechanisms. Endorphin levels in human colostrum are two-fold greater than corresponding maternal plasma levels; however, the high endorphin levels in human milk decrease as lactation continues. The aim of this study was to determine the β-EP concentration in colostrums of women residing in Burkina Faso and Sicily. In addition, we investigated the source of potential differences in β-EP levels between these populations, especially ethnic sources of these deviations. Methods The concentration of β-EP was determined in the colostrum from the first 3 d subsequent to delivery by an enzyme immunoassay as immunoreactive material (IRM). Results The production of β-EP in the colostrum was significantly higher in Burkinabe mothers (0.83 ± 0.04 ng/mL) than in Sicilian mothers (0.31 ± 0.02 ng/mL) at 24 h after delivery. Colostrum levels of β-EP declined progressively during the first 3 d after delivery in both populations (0.64 ± 0.1 and 0.28 ± 0.015 ng/mL, respectively, at 72 h). The level of β-EP-IRM correlated significantly with pain and psychological involvement during and after delivery. In addition, the correlation between β-EP-IRM and length of stage II of labor was significant (P < 0.0001) in the colostrums of Sicilian mothers who received ergot derivatives, episiorrhaphy, and child birth preparation. The correlation between β-EP-IRM and length of stage II was less significant (P < 0.001) in the colostrums of Burkinabe mothers who received neither ergot derivatives nor child birth preparation. Conclusion During the first 3 d after labor the β-EP-IRM concentration in the colostrums of Burkinabe mothers differs from that of Sicilians. In addition, because Burkinabe women produce a larger volume of colostrum, their newborns receive, during the first days of life, a larger absolute amount of β-EP-IRM, likely resulting in better postnatal fetal adaptation.