First Minister Carwyn Jones has led Welsh messages of congratulations to the Duke and Duchess of Cambridge.
"Many congratulations to the Duke and Duchess of Cambridge on their wonderful news" he tweeted.
The Leader of the Welsh Conservatives in the Assembly, Andrew RT Davies, also tweeted a message of support, describing the news as "the perfect end to a Jubilee year.
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Medication designed for animals was taken from the building in Abertillery on Thursday night.
More than a thousand riders will be taking part in a series of events in and around the town.
Some warm spells of sunshine will develop, although scattered heavy and thundery showers are also expected during the afternoon.