Table 3.

Infant-related factors affecting nutritive and non-nutritive components of human milk.

Factors	Effect on nutritive or non-nutritive components of HM	Evidence	References
Birth weight	Higher birth weight increases HM intake	Evidence probable	(174–176)
Gestational age at birth	Preterm birth increases true protein in colostrum	Evidence probable	(177–184)
	Preterm birth decreases lactose in colostrum	Evidence probable
	Preterm birth decreases minerals, Ig, growth factors	Lacking
Sex	Male infants consume higher amounts of HM than female infants	Evidence probable	(185–188)
	Energy and lipid content of HM is higher after giving birth to male infants	Inconsistent or lacking
Age (stage of lactation)	Advanced stage of lactation increases HM intake, as well as energy, total lipids and HMO (3 FL) content	Evidence probable	(4, 7, 98, 137, 186, 189–213)
	Advanced stage of lactation has no major impact on lactose and some HMOs (e.g., 3 SL)	Inconsistent or lacking
	Advanced stage of lactation decreases total and major proteins, as well as some HMOs (e.g., 2 FL), immune factors, whey/casein, vitamins and zinc	Evidence probable
Feeding session	Hindmilk has higher energy and total lipids compared with foremilk	Evidence probable	(195, 196)
Feeding—time of the day	Mid-day feeding demonstrates higher energy and total lipids	Lacking	(214, 215)
Variations between breasts	Milk output from the right breast is greater than from the left breast	Inconsistent	(195, 196, 216–224)
	Energy content in HM from the left breast is higher than from the right breast	Inconsistent or lacking
Circadian variability	Lipids and lipolytic enzymes in HM peak at mid-day	Evidence probable	(150, 214, 215, 225–239)