Age constraint for babies on international flights

What is the minimum age of a baby to travel on international flights.Is it dependent on the carrier or is there a general rule.Also aftre which month of pregnancy a woman cannot take a international flight.

I think it varies from airline to airline but BA I believe for a baby something like not under 12 days. Babies ears however are not fully developed till 12 weeks or so I read somewhere so they might have more trouble if they are too young. With my baby I made sure he was sucking something on take off and landing...he was 6 months at the time. As for a pregnant woman I think after 34-36 weeks but you might be able to agree with the airline if you called them personally

Aks, as the seatbelts on most commercial airliners do not fit smaller children the main concern if your child is under five years old is whether or not he or she will fit into the over-head storage compartment. It's fine, they provide pillows for them.

My daughter had a passport at 2 months of age, and it was recommended (by the health authorities) that we wait until then to travel with her as she would have received her first set of immunisations (in the UK) at that age. We travelled the same week.

I flew at 34 weeks pf pregnancy, and then hid myself under a really big coat on the flight back from england as I had read that BA wouldn't allow me to travel if they knew!
Brought kiddo back at about 5 weeks, he was fine.