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. 2021 Nov 1;73(5):e115-e119.
doi: 10.1097/MPG.0000000000003214.

Insulin Concentration in Human Milk in the First Ten Days Postpartum: Course and Associated Factors

Elise Mank  1 , Letty van Toledo  1 , Annemieke C Heijboer  2 , Chris H P van den Akker  1 , Johannes B van Goudoever  1
Affiliations

Insulin Concentration in Human Milk in the First Ten Days Postpartum: Course and Associated Factors

Elise Mank et al. J Pediatr Gastroenterol Nutr. .

Abstract

Background objectives: Human milk (HM) is better tolerated than formula in preterm infants. Insulin, which is naturally present in HM but not in formula, has been suggested as a key factor for feeding tolerance, as it appears to stimulate intestinal maturation. Its precise concentrations during the early postnatal period, however, remains unknown. The objective of this study was to assess the natural timecourse of the HM insulin concentration during the first ten days postpartum. The effect of preterm delivery, maternal obesity, and diurnal rhythm were also assessed.

Method: HM was collected from 31 non-diabetic mothers (21 preterm [gestational age (GA) < 37 weeks]; 10 at-term [GA ≥ 37 weeks]) on ≥ 4 time-points per day during the first five days, and once on the tenth day postpartum.

Results: The HM insulin concentration declined rapidly within the first three days postpartum (day 1: 516 [312-1058] pmol/L; day 3: 157 [87-299] pmol/L), after which the concentration remained relatively stable. The insulin concentrations were higher in HM from obese mothers than from non-obese mothers (P < 0.001). Preterm delivery did not significantly affect HM insulin concentrations when adjusted for maternal pre-pregnancy body mass index category (P = 0.270). Diurnal rhythm was characterized by an insulin concentration decline throughout the night (P = 0.001), followed by an increase in the morning (P = 0.001).

Conclusion: The HM insulin concentration declines rapidly in the first three days postpartum, follows a diurnal rhythm, and is higher in obese mothers compared to non-obese mothers. HM insulin concentrations are not affected by preterm delivery.

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Conflict of interest statement

Conflict of Interest: J.B.v.G. is member of the National Health Council, Chair of the Committee on Nutrition and Pregnancy, and Director of the Dutch National Human Milk Bank. He does not receive any honorarium for his services. C.H.P.v.d.A. is a member of the scientific advisory board of Nutricia Early Life Nutrition and Baxter. He gives educational lectures for Nutricia Early Life Nutrition and Baxter. Reimbursements and speaker honoraria are transferred to hospital research funds. The remaining authors have no conflict of interest to disclose.

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