This aspect must be evaluated in association with the pronounced body - size variation within the sample, which implies marked
differences between age ranges and a
considerable degree of sexual dimorphism in Au.
For low - income families headed by single mothers, the associations
between maternal employment and children's cognitive and social development tend to be neutral or positive, but much of this
difference is a function of pre-existing
differences between mothers who are or are not employed.2, 3,4,5 The effects of maternal employment on children's development also depend on the characteristics of employment — its quality, extent and timing — and on the child's
age.2, 6,7 On the other hand, poverty has consistently negative associations with young children's development, but here, too, there is
considerable controversy about the causal role of income per se, as opposed to other correlates of poverty.8, 9,10,11,12,13