Baby Girls

Human infants need constant attention and contact with other human beings because they are unable to look after themselves. Unlike other mammals, they cannot keep themselves warm, move about, or feed themselves until relatively late in life. It is their extreme neurological immaturity at birth and slow maturation that make the mother-infant relationship so important. The human infant's brain is only about 25% of its adult weight at birth, whereas most other mammals are born with 60-90% of their adult brain size. The young of most other mammals become independent of their parents within a year, whereas humans take 14 to 17 years to become fully developed physically, and usually longer than that to be fully independent.

Apart from being a natural characteristic of our species, constant proximity to the mother during infancy is also made necessary by the need to feed frequently. Human milk is composed of relatively low amounts of protein and fat, and high amounts of quickly absorbed and metabolized sugars. Therefore the infant's hunger cycle is short, as is the time spent in deep sleep. All of these factors seem to indicate that the custom of separating infants from their parents during sleep time is more the result of cultural history than of fundamental physiological or psychological needs.

Sleep laboratory studies have shown that bed-sharing, instead of sleeping in separate rooms, almost doubled the number of breast-feeding episodes and tripled the total nightly duration of breast-feeding. Infants cried much less frequently when sleeping next to their mothers, and spent less time awake. We think that the more frequently infants are breast-fed, the less likely they are to die from cot death.

Our scientific studies of mother and infants sleeping together have shown how tightly bound together the physiological and social aspects of the mother-infant relationship really are. Other studies have shown that separation of the mother and infant has adverse consequences. Anthropological considerations also suggest that separation between the mother and infant should be minimal. Western societies must consider carefully how far and under what circumstances they want to push infants away from the loving and protective co-sleeping environment. Infants' nutritional, emotional and social needs as well as maternal responses to them have evolved in this environment for millennia.