I will be a parent
If you decide to take paid parental leave (maternity, paternity or adoption leave) nothing changes. Your own and BA's contributions will continue.
If you decide to take a period of unpaid leave after your paid parental leave ends, your pension 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 parental leave.
You should think about updating your Notice of Wish once you become a parent.
See My children get for more information regarding dependent children's allowances.