Crossed Computers

Crossed Computers was the sign under which the Doctor was born, and was also the symbol of the maternity service on Gallifrey.

The Fourth Doctor mentioned as such to Lady Adrasta's astrologer Organon. (TV: The Creature from the Pit).

However, since the Thirteenth Doctor learned from the secret of her own past lives as the Timeless Child, the knowledge surrounding the Doctor's Gallifreyan birth sign could well have been a Matrix construct, similar to Brendan's story. (TV: The Timeless Children)

Behind the scenes

 * To date, the Doctor remains the only Time Lord character in the series to have their birth sign revealed on-screen.