Changes in leptin concentrations in human breastmilk during 180 days of lactation period. (A) Box plot ofleptin concentrations in milk samples were obtained frombreastfeeding women taking part in the longitudinal study at 1–3 days(median = 2 days), 4–14 days (median = 8 days) at 15–30 days (median = 25 days) after birth. (B) Box plot of leptin concentrations in milk samples collected from 160 breastfeeding women taking part in the cross-sectional study at 1–180 days and they grouped into five intervals: 1–3 days (median = 2 days), 4–14 days (median = 8 days), 15–30 days (median = 25 days), 31–90 days (median = 60 days) and 91–180 days (median = 144 days). The filled circle at the upper and the lower part of each box show the 5th and 95th percentiles, respectively. *p < 0.05; **p < 0.01; ***p < 0.001 when compared with the values observed for 1–3 days.