P&F they cant force you to take hols before baby is born but it might be worth taking some in case baby is early...bear in mind that come Sept you will have presumably wanted some time for a break in the summer - it gets very hot being preggers in the summer as you get bigger its harder to cool off IYKWIM. Most employers though will understand if you have booked hols before birth that if bubs is early you stil intend to have it - after all they have to give so much paid mat leave and its not in their interest to try to take it away - bad PR - in the end you may end up with a day or two less unpaid mat leave but by then you will be into next years holiday entitlement anyway and that is paid