Why PbH4 acts as an strong reducing agent?

Dear Student , its due to inert pair effect , as there the Pb is the last element of group 14 elements so there we see that its Pb²+ state is more stable than Pb⁴+ as there the 6s² electrons of it remain deep seated and so does not takes part in bond formation so there is a huge tendency of conversion of Pb⁴+ to Pb²2+ by gaining of two electrons. Regards !