WFH request during pregnancy

Hi All, As per policy 6 months of WFH is allowed for expectant mothers and I have already availed it for 4 months. Is there any possibilities to take WFH during the entire pregnancy period? I am checking this as I have some medical conditions and doctor has advised to take full rest till my delivery.. Are you aware of anyone who have taken 9 months of WFH.. Any input on this would be really helpful.

Note: I initially informed this to my manager but I doubt about HR approval when I apply more than 6 months.