… if I developed pre-eclampsia in late pregnancy or during labour?

Although the placenta does seem to play a role in the development of pre-eclampsia, it does not exclude using it for encapsulation. After the birth your placenta will be examined routinely for irregularities and problems yet more often than not, the placenta is fine and still fit for encapsulation. If your caregivers detect an issue or infection in the placenta, it will be sent to pathology and therefore deemed unfit for encapsulation.