Maternal areola pH: A chemical basis for mother-infant recognition

The human female's areolar region is the point of arrival of a natural progression from birth to breastfeeding continuum, supported by numerous functional features.

The aim of this study was to look more closely into the areola' skin chemical signals that are uniquely important for mother-infant chemoemission, chemoreception, and breastfeeding continuum.

A dermatological study of the areolae and corresponding breast quadrants was undertaken on 71 healthy, at-term women. Areolar and corresponding breast quadrant pH were assessed pre-partum and 1 and 2 days post-partum using a corneometer (Soft Plus 5.5; Callegari S.P.A., Parma, Italy).

Pre-partum, the pH of the areola was significantly higher than the pH of the breast quadrant (4.25 ± 0.26 vs. 4.06 ± 0.44, p < 0.015). Post-partum, the pH of the areola was significantly higher that the pH of the breast quadrant both on day one (4.28 ± 0.31 vs 4.01 ± 0.25, p < 0.001) and on day two (4.39 ± 0.19 vs 4.01 ± 0.16, p < 0.001), respectively. In addition, pre-labor pH of the areola increased on day one post-partum and significantly on day two postpartum (4.25 ± 0.26 vs 4.39 ± 0.19, p 0.004). Moreover, the pH of the areola increased significantly from day one to day two post-partum (4.28 ± 0.31 v s 4.39 ± 0.19, p < 0.041).

Our findings show, for the first time, that the areola has a higher pH than the surrounding breast skin, and this increases from day one to day two postpartum. We believe that the pH changes of the areolar region may act as a unique chemical signal to guide the infant directly to the nipple.