P&O have two child free ships. The Arcadia ( no plans to go to the Panama that I could see and the Artemis which is going there later. Other cruise lines where children are not catered for include: Saga, Azamara, Silversea, Crystal and Seven Seas. One more obvious observation most ships are fairly child free during term time although not everyone has a choice of when they are able to take a holiday and American schools have different holiday periods to the UK..Hope that helps....Nei.
P&O Arcadia is child fre.
Many of luxury cruises do not have many children onboard, however, I doubt the time of year and the baltics really appeals to many families so you should be pretty safe that there will not be many kids on board.