It was Dr John Bowlby in Maternal Care and Mental Health (1951)  who argued that infants form a special relationship with their mother, which is qualitatively different from the relationship which they form with any other
kind of person. Bowlby described this as the process of 'monotropy'. By a mechanism which he saw as very similar to imprinting, Bowlby considered that the young infant developed a firm attachment to its mother within the first six months of life, and that if this attachment or bond was then broken the infant would suffer serious consequences. "Even good mothering is almost useless if delayed after the age of 2 and a half".
From the beginning Bowlby's work assumed a political dimension as his arguments were seized by one group or another to show that either fathers should provide for their
family or that mothers should stay at home to look after their children, so much so that the World Health Organisation felt obliged to publish a rebuttal called<unk>  of maternal care. A reassessment of its effects' (1962). Professor Sir Michael Rutter  in<unk>  Reassessed (1972), which New Society described as a, 'classic in the field of child care', showed that children are not invariably so damaged and that, in any event, other people, including their fathers, are also very important to children.
According to Schaffer in 'Social Development' (2000)  it seems likely that social convention explains whatever differences are observed amongst parents and that when fathers do assume the principal responsibility for their children such differences disappear. This is borne out by the study by Field (1978)  of standardized parent infant interaction. The notion that fathers are necessarily less competent with or less responsive to their children receives no support from physiological measures (Berman, 1980)  or research evidence (Parke, 1981).
It was as a result of this body of criticism that Bowlby went on to diffuse the concept of<unk> ' into the attachment theory and it is now generally accepted that either or both parents may be the child's 'primary carer'.
Maternal deprivation
Perinatal infection
Multiple birth
Maternal immunization
Passive smoking
Sedentary lifestyle
Premature birth
Childhood obesity