In short no without the tenants agreement. We had the same problem I was pregnant when we purchased our now home 2 years ago.
If the house is sold with a lease attached the tenants have all the rights. You can offer them money for example two months rent to move by the settlement date but it's totally up to them. We did the above but the tenant refused. They wanted the money but without the clause of moving by settlement we declined. In the end we moved when DS was 8 wks old.
I do hope you find away or they accept an offer. My only advice is if you can't get in before bub is born is to do as much packing prior to birth. It maybe a pain with all the boxes etc but I had SPD & DS2 was a big baby (ie I was huge) & decided to wait. This wasn't the best decision in my case as we didn't get that honeymoon period I was packing from the day I got home. DS2 wasn't a baby that just fits in lol.
Good luck very exciting still new baby & home x