Tickets for the Games first went on sale in March last year, since when some of those lucky enough to secure seats in the ballots have given birth.
The mumsnet.com website was flooded by indignant mothers earlier this year when they discovered they could not take their babies to the Games unless they bought a separate ticket. Most venue were sold out by then.
After complaints and suggestions that the policy might be in breach of sexual equality laws, organisers agreed to review the situation.
"Anyone who purchased a ticket...and did become pregnant, had a baby and wants to take the baby to the Games will be able to do so," LOCOG chief executive Paul Deighton told a conference call about the latest ticketing arrangements.
"The baby of course will be under 12 months old and then will be let in if securely strapped to the parent or carer by way of a baby carrier, papoose or sling."
LOCOG said their 'babes in arms' policy would apply to all venues with the exception of Wembley Stadium, Newcastle's St James' Park, Manchester's Old Trafford and the North Greenwich Arena.
At those venues, existing licensing agreements meant that all spectators would require tickets regardless of age.