Obstructed labour, a major cause of maternal and fetal mortality and morbidity, is largely attributed to Cephalo-Pelvic Disproportion (CPD), where the fetal head is too large for the maternal pelvis. I propose that investigating the genetic and developmental factors influencing morphological covariation between fetal skull and maternal pelvis could significantly advance our understanding of CPD. Using imaging, geometric morphometrics and Multivariate Genotype-Phenotype mapping I create a comprehensive genotype-phenotype map of skull- pelvis covariation in adult mice. Additionally, I evaluate the effects of prenatal estradiol and testosterone on the covariation between fetal head and maternal pelvis. This approach challenges the traditional view of CPD, which treats maternal pelvis and fetal head as separate traits under distinct evolutionary pressures, by offering a more integrated perspective on the factors contributing to obstructed labour.