It is not known what constitutes an optimal diet in infancy. There are relatively few studies of weaning practice in the UK, and there is a need for prospective data on the effects of infant diet and nutrition on health in later life. We describe the dietary patterns, defined using principal components analysis of FFQ data, of 1434 infants aged 6 and 12 months, born between 1999 and 2003. The two most important dietary patterns identified at 6 and 12 months were very similar. The first pattern was characterised by high consumption of fruit, vegetables and home-prepared foods (‘infant guidelines’ pattern). The second pattern was characterised by high consumption of bread, savoury snacks, biscuits and chips (‘adult foods’ pattern). Dietary pattern scores were correlated at 6 and 12 months (r 0·46 ‘infant guidelines’; r 0·45 ‘adult foods’). These patterns, which reflect wide variations in weaning practice, are associated with maternal and family characteristics. A key influence on the infant diet is the quality of the maternal diet. Women who comply with dietary recommendations, and who have high intakes of fruit and vegetables, wholemeal bread and rice and pasta, are more likely to have infants who have comparable diets – with high ‘infant guidelines’ pattern scores. Conversely, women whose own diets are characterised by high intakes of chips, white bread, crisps and sweets are more likely to have infants who have high ‘adult foods’ pattern scores. The effects of these patterns on growth and development, and on long-term outcomes need to be investigated.

The nutritional status of both women and men before conception has profound implications for the growth, development, and long-term health of their offspring. Evidence of the effectiveness of preconception interventions for improving outcomes for mothers and babies is scarce. However, given the large potential health return, and relatively low costs and risk of harm, research into potential interventions is warranted. We identified three promising strategies for intervention that are likely to be scalable and have positive effects on a range of health outcomes: supplementation and fortification; cash transfers and incentives; and behaviour change interventions. On the basis of these strategies, we suggest a model specifying pathways to effect. Pathways are incorporated into a life-course framework using individual motivation and receptiveness at different preconception action phases, to guide design and targeting of preconception interventions. Interventions for individuals not planning immediate pregnancy take advantage of settings and implementation platforms outside the maternal and child health arena, since this group is unlikely to be engaged with maternal health services. Interventions to improve women's nutritional status and health behaviours at all preconception action phases should consider social and environmental determinants, to avoid exacerbating health and gender inequalities, and be underpinned by a social movement that touches the whole population. We propose a dual strategy that targets specific groups actively planning a pregnancy, while improving the health of the population more broadly. Modern marketing techniques could be used to promote a social movement based on an emotional and symbolic connection between improved preconception maternal health and nutrition, and offspring health. We suggest that speedy and scalable benefits to public health might be achieved through strategic engagement with the private sector. Political theory supports the development of an advocacy coalition of groups interested in preconception health, to harness the political will and leadership necessary to turn high-level policy into effective coordinated action.