Our analyses show that both mother's educational attainment and CTVB predict breast-feeding establishment. CTVB is, we suggest, the more useful marker since it can be obtained independently of the subjects concerned and, besides being more convenient and accessible, is therefore more objective. CTVB is also a novel finding, remarkable in the consistency with which it predicts the successive phases of breast-feeding in different groups of a cohort of UK mothers (Figure1). Moreover it predicts, with equal symmetry, the maternal socio-demographic circumstances. Linking these two paradigms then shows how breast-feeding is socially governed in the UK. 80% of new babies taken home to large, mostly detached and owner-occupied homes (CTVB 'E+') were breast-fed. Of their counterparts in modest homes – mostly rented rooms, flats or conjoined houses (CTVB 'A') – only some 50% were breast-fed and it was seven times more likely that their mothers would be smokers. The latter young families also had significantly less weekly income, had had less education, and were more likely to have needed the subsidised provision of baby equipment by the DSS. Superficially, much of this is hardly new information and, therefore, no surprise. But the pioneering use of CTVB as the demographic marker in the study is unique: it gives us unequivocal categorisation, objectivity and multiple insights. The study data – from 1991/2 – may be challenged as somewhat out of date but they can certainly be taken as representative, participants being an adequate and randomised sub-set of the 14,541 ALSPAC (13) responders, mothers then confined in Avon.
The main implications of the study are probably threefold:
I. for the distribution and health promotion of breast-feeding and the implicit resource allocation determinants;
II. for the association of breast-feeding and cigarette smoking;
III. for the prospects of CTVB as a valid socio-economic marker.
I. The social mal-distribution of good feeding practice, viz. breast-feeding during the initial months of life, carries serious implications for health promotion. With the exception of seeing bottle-feeding as more convenient (implications being less 'tied' to the baby and never having to breast-feed in public), early beliefs and attitudes to infant feeding are equivalent in all the women. Despite this, far fewer mothers from less prosperous homes eventually put their newborns to the breast. This discrepancy deserves further examination: there may be clues that could help clinicians raise breast-feeding rates in these women and, therefore, overall. But enlightened or not, more sensitive and more determined counselling is obviously necessary where it is most needed – among the socio-economically deprived. These can now be spotted, prospectively and simply, by referring to the CTVB of their addresses at antenatal booking. The implications for resource allocation to UK general practice and other childcare facilities in the community, for optimum manpower dispersal, are obvious and reinforce previous conclusions [20]. And, as a rider, our findings also suggest that local or regional claims for 'success' in achieving high breast-feeding rates should be disputed until they have been modulated by social class distribution in the catchment population.
II. The inverse association between breast-feeding and smoking in young mothers is well known. There is a consensus that the link is a social rather than a physiological one [21] for although there is evidence that smoking diminishes hypothalamic activity and, therefore, potential milk production and flow [22], the strength of this inhibition is contentious and probably marginal. Our findings reinforce the dominance of the social mechanism. Among the numerous factors tested, smoking included, CTVB is the strongest predictor for breast-feeding. Being a smoker neither deters nor determines infant feeding habit: of our 211 mothers who smoked in the last two months of pregnancy (18.5%), there is still a progressive diminution of breast-feeders from CTVB 'E+' women to their 'A' counterparts.
III. The unifying and innovatory aspect of this study is the use of CTVB in grouping study subjects for cross-sectional comparison. The proposal that in so doing we are placing women in a socio-economic spectrum is supported by our previous publications [16, 23] and reinforced, strongly, by the subsidiary findings of the study itself. But whether CTVB is, or is not, a satisfactory socio-economic surrogate, it certainly has some inherent strengths to recommend it. It is an official and categorical device instituted and maintained by a body (The Government) outside the debate and can therefore be considered objective. It is also universal, comprehensive and stable. The bands need revision but this is scheduled for England and has already occurred in Wales [24]. CTVB is also readily available, on-line [15], for every property in the UK and, since it is an individual household attribute, is entirely free of the perils of Census data interpretation [10] and of the so-called 'ecological fallacy' [25] inherent in gleaning aggregated data from within a variety of geographical boundaries. And unlike educational attainment, which this study also shows to be a marker of breast-feeding, CTVB can be obtained without access to, and enquiry of, the individuals concerned. This makes it easier to obtain on a massive scale if need be and CTVB certainly meets the essential criteria for a valid socio-economic marker as specified by Wagstaff and colleagues in 1991 [26]: it reflects inequality, does so across the whole population, and is sensitive to changes in that population. In fact CTVB could have a significant future as an epidemiological tool: many other studies suggest themselves.