I will be a parent
While you are on paid maternity or paternity leave nothing changes. Your own and BA's contributions will continue.
When you enter the unpaid period of maternity leave, contributions will stop (so your pension stops building up) but you will still be covered for death benefits. When you return to work you will have the choice to pay the contributions you missed.
If you decide not to return to work your pension will be calculated up to the last day of your paid maternity leave.
You should think about updating your notice of wish once you become a parent.
Update my Notice of Wish