Parents from Pontypool have beaten odds of 160,000 to 1 to have identical triplets.
Ffion, Maddison and Paige Gilbert were born on 2 August.
When parents Karen and Ian went to the doctors early in the pregnancy, they were fearful of a miscarriage, but shocked to learn they were due to have three babies.
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The peer will attack Prime Minister Theresa May for failing to represent the 48% who voted in favour of Remain.
Paul Flynn, MP for Newport West, will open the debate in Westminster Hall.
It will represent another boost to the region, after the announcement Deca Sealand was chosen for a repair hub for defence aircraft.