Maternal somatostatin levels and their correlation with infant birth weight

Samples of blood were obtained from 52 primiparous breast-feeding women 4 days post partum. Thirty-six of the mothers were still breast-feeding 3–4 months later and had further blood samples taken. Somatostatin levels were analyzed by radioimmunoassay. A highly significant rank correlation (P = 0.0001) between average somatostatin levels on the two occasions was established, although somatostatin levels recorded 3–4 months post partum were significantly higher than those found 4 days post partum (P < 0.01). Furthermore, somatostatin levels obtained 4 days and 3–4 months post partum were inversely related to the birth weight of their children (P = 0.006 and P = 0.03). The significant negative correlation between somatostatin levels recorded 4 days post partum and birth weight of the infants persisted only when non-smokers were investigated. A strong positive correlation between infant birth weight and weight of placenta was found (P = 0.0001) and a negative correlation (P = 0.04) between somatostatin levels and placental weight. A stepwise regression was performed to explain the importance of somatostatin levels in birth weight. Somatostatin levels and smoking had an almost equal influence on the variation in birth weight (0%). It is suggested that low maternal somatostatin levels are related to an efficient storage of nutrients in the fetoplacental unit, thereby leading to a high birth weight.