The girls, who gave evidence by video link, told the court that while on a day out in Sligo town they bought a pregnancy test, which Melissa Mahon used in McDonald's.
One of the girls, when asked what Melissa Mahon's reaction was, replied that she was 'kind of delighted, in a way' when the result was positive.
The evidence comes on day 12 of the trial of Ronald McManus, also known as Ronnie Dunbar, of Rathbraughan Park in Sligo who denies murdering the schoolgirl in September 2006.
It follows earlier evidence from two other witnesses who said they had been told that Melissa was pregnant.
