The trial commences preconception as studies by Catalano et al. [53] suggest that a major part of the risk of macrosomia originates in early pregnancy/prepregnancy and adverse pregnancy outcomes are associated with poor maternal nutrition at conception; maternal insulin resistance and hyperglycaemia in the very earliest stages of pregnancy alter placental anatomy and physiology in ways that persistently affect transplacental fetal nutrient supply and fetal fat accretion, as well as bilateral maternal-feto-placental cross-talk, with consequences for later postnatal health. The gene discussed is INS; the disease is Large for gestational age.