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Approfondimenti scientifici

From Colostrum to Mature Milk: Tailored Nutrition for the Newborn

Dr. Alexandra Semjonova, Prof. Rosaria Taverna
FOCUS: Breast milk and nutritional benefits

Exclusive breastfeeding during the first six months of life represents the nutritional benchmark for the health and well-being of the newborn. Subsequently, with the gradual introduction of complementary foods according to the baby’s signs of readiness, it can be continued beyond the first year of life as a complement to the diet. Even when practiced for a limited period, breastfeeding offers significant benefits, providing essential nutrients and key bioactive components at every feeding.

Colostrum

Colostrum is a thick, viscous, yellow-orange fluid produced by the breast from the third trimester of pregnancy onward. Its secretion continues during the first few days after birth. It is an exceptionally suitable food for the newborn: low in fat but rich in carbohydrates, proteins, vitamin A, and antibodies. It is highly digestible and has a powerful nutritional and immunological effect.

Thanks to its laxative effect, colostrum facilitates the elimination of meconium (the newborn’s first stools) and helps remove excess bilirubin, thereby contributing to the prevention of neonatal jaundice. The secretory IgA it contains coats the infant’s intestines, protecting them from viruses and bacteria while promoting the development of a healthy intestinal microbiota.

Colostrum is produced in small quantities, perfectly matched to the newborn’s stomach capacity and the still immature function of the kidneys.

From Colostrum to Mature Milk

During the 2–3 days following birth, colostrum gradually changes into transitional milk, whose composition progressively evolves: the color becomes more opaque and white, while both the caloric content and the volume produced increase. By the third or fourth day after birth (with a slightly longer timeframe following a cesarean section), the so-called milk coming in occurs, marking the beginning of mature milk production. However, the transition between these stages is subject to considerable individual variability.

During a single feeding, breast milk changes in composition. Foremilk (produced during the first minutes of feeding) is thinner and richer in water and lactose, helping to quench the newborn’s thirst. Hindmilk, consumed during the later stages of feeding, is richer in fat and is therefore more satisfying.

Breast milk is a dynamic substance whose composition continuously adapts to the baby’s needs. Its composition varies:

  • From one woman to another
  • According to the stage of lactation
  • Throughout the day
  • In response to the newborn’s specific needs
Energy Value and Nutritional Adequacy

Breast milk has an average energy value of 65 kcal per 100 ml. Considering an average intake of 200 ml per kg of body weight per day, a newborn’s daily energy requirements (approximately 130 kcal/kg/day) can be fully met by breast milk.