Assuming Aug.4 is the date of BHO's birth, and were he born in Kenya, it's more than likely that Stanley Anne flew from Kenya to the UK, from the UK to New York, then New York to Washington state, a sizable amount of travel back in 1961, especially with her newly hatched beelzebaby in tow.
Throwing this out there - do airlines typically keep manifests from years ago? Odds are that BOAC was the carrier from Kenya to the UK then.
Some investigation of transportation records into and out of Kenya during August 1961 may turn something up.
IIRC, along about middle of the afternoon on the original big thread of a couple days ago, someone posted an airline schedule.
Yes, where Ann was before the birth is the $64K question. A month after the birth, there was a get together of some of O. Sr.’s Hawaiian college friends (maybe to start the new semester?) and they had no idea a baby was on the way.