Poorer health has been consistently associated with both low levels of social support and material deprivation. It has been proposed that social support constitutes a causal link between health and deprivation such that those with lower socio-economic status have poorer health because their lack of social support makes them more vulnerable to disease. This assumption was tested in this study for women moving from pregnancy to early motherhood. The sample of 9208 women was drawn from the Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC). Health status was measured by self-report of morbidity for three contrasting conditions: backache, depression and urinary infection. Data were collected by self-completion questionnaire at eight weeks prepartum and at eight weeks postpartum. The sample was divided into four groups for each condition on the basis of identification of the condition (1) on both occasions, (2) on neither occasion, (3) at eight weeks prepartum only, and (4) at eight weeks postpartum only. Chi-square tests were used to measure the association between presence or absence of a condition as defined above, material deprivation and low social support. Responses on an eight item social support questionnaire tapping emotional, instrumental and communal aspects of perceived social support were compared between these groups for each condition. Results showed significant associations, in late pregnancy and early motherhood, between poorer health and both material deprivation and low social support for two of the three conditions, depression and urinary infection. Changes in levels of perceived social support occurred as a consequence of motherhood; the percentage of women perceiving their partner to be supportive decreased as did the percentage of those who felt that their family or friends would help with financial difficulties; in contrast, the percentage of those perceiving that other mothers/neighbours offered support increased from late pregnancy to early motherhood. The extent and direction of such change was consistently associated with the presence or absence of depression, but not with backache or urinary infection. When mental health "improved", in that depression was present pre- but not postpartum, the percentage feeling supported increased and vice versa. This pattern was in evidence across all items of social support. It was concluded that perceived social support was unlikely in itself to constitute a causal link between poorer health and lower socio-economic status. In this context the relationship between social support and depression requires further consideration, particularly the extent to which they constitute component parts of a more general feeling of emotional well-being, a construct which is, in its turn, in need of further articulation in relation to health outcomes.