Here is the BA policy on pregnancy: https://www.britishairways.com/en-gb...nancy#pregnant

Travelling when you're pregnant

For your and your baby’s safety you cannot fly after:

• the end of the 36th week if you are pregnant with one baby
• the end of the 32nd week if you are pregnant with more than one baby

We recommend that you carry a confirmation from your doctor or midwife of whether your pregnancy is single or multiple, your expected due date, and there are no complications.