Changes in maternal secretory immunoglobulin a levels in human milk during 12 weeks after parturition

Background Immune factors in human milk change in concentration after delivery. However, this concentration change during the early postpartum period has not yet been investigated in detail. Methods We measured Secretory IgA (SIgA) levels in the human milk of 91 postpartum mothers (after vaginal delivery) by using an enzyme immunoassay, in postpartum day 3, and weeks 1, 2, 3, 4, 8, and 12. Results The SIgA concentration gradually declined over the 12-week period, with the highest level recorded in day 3. At week 4, the SIgA levels decreased to half the initial levels. Although the difference in concentration from one week to the next was remarkable, the decrease in concentration was rapid in the first 4 weeks but gradual from week 4 to week 12. Conclusions The SIgA levels gradually decreased up to week 12. However, the concentration of SIgA in breast milk did not change constantly. It changed relatively rapid until 4 weeks after childbirth, and because the concentration from the third day to the eighth week became 50%, it was understood that the change was temporal. Am. J. Hum. Biol. 25:399403, 2013. (c) 2013 Wiley Periodicals, Inc.