Prenatal Metamorphosis

A prenatal metamorphosis is a rare condition when the superhuman fetus undergoes metamorphosis while developing in the mother’s womb. Normally, a superhuman would undergo this process at puberty, but in some cases, it may occur at birth. As such, this may result in issues and congenital disorders while in the womb that may lead to more complications later in life if they survive. 
The results are unpredictable as it is more difficult to know the possible abilities the fetus may manifest than it is for an adolescent or adult. The undergoing transformation will most definitely lead to prolonged gestation and dangerous transformations that may risk the fetus and mother’s wellbeing, which is especially true if the ability is of a spontaneous-destructive nature. It may be necessary to delivery the baby before the transformation ends - which puts the baby at risk for incomplete metamorphosis.
The causes are unknown. It is possible that genetics and family history of early metamorphosis may play a role as a predisposing factor, as well as the nature of the abilities.