It has been proposed that additional physical exercise in pregnancy may have a positive impact on birth weight. The development of interventions aimed specifically at increasing physical exercise in pregnancy may therefore produce an important benefit to the health of the public. However, although the effects of such approaches might apply to a very large number of pregnant women and babies across the community, the size of the effect in any one individual is likely to be small. In order to study this properly it has therefore been suggested that a number of large studies should be pulled together in order to determine: (a) is there an effect at all; (b) how large is it; (c) does it matter when the exercise takes place, what form it takes and how extensive it is; (d) are there other factors that modify the impact of physical exercise.

InterConnect is an EU-FP7 funded project that is enabling cross-study analyses to facilitate research to understand the differences in diabetes and obesity between populations, including analyses of gene-environment interaction. At the core of the network is a technology platform for the harmonisation and analysis of data across studies in a manner that avoids the complex ethical and legal issues associated with the physical sharing of data. The investigation that is described above will be one of the initial analyses that will be carried out on the InterConnect platform. It will pull together data from 8 studies including a total of 144,349 participants. ALSPAC is one of the studies that has been invited to be part of the InterConnect consortium. In order to enable the data from all of the involved studies to be effectively analysed together, while ensuring absolute privacy and confidentiality of the data from individual participants, the data analysis will be undertaken using a new software tool called DataSHIELD that has been developed in collaboration with ALSPAC.