Compared to underweight mothers, those with normal weight (β = 161.6 × 10−3, p < 0.05), overweight (β = 145.3 × 10−3, p < 0.05) and obesity (β = 248.9 × 10−3, p < 0.05) had higher Lg OPN levels in HM. Here, SPP1 is linked to obesity due to melanocortin 4 receptor deficiency.