Such perturbations to placental development may reduce foetal growth due to decreased nutrient transport via the placenta (Sullivan et al., 2009c) generating a decrease in birth weight (Perry et al., 1999; Micke et al., 2010c), or alternatively dichotomous placental development (as in the LH group) may be attendant to increased birth weight and associated dystocia. This evidence concerns the gene PLOD1 and dystocia.