Czech-born Mirgova, 26, was arrested five months ago after she wed a Nigerian man for cash so he could stay in Britain.
Shortly afterwards she became pregnant by her long-term boyfriend.
At Burnley Crown Court, Alan Wolstenholme, defending, argued she should get a suspended term because of her condition.
But Judge Lunt told Mirgova she would not escape a prison sentence just because she had opted to become pregnant.
She said: ‘You have now chosen to become pregnant a third time. It would seem this child was conceived around the time of your arrest or soon thereafter.
‘You clearly understand that without women like you these sham marriages could not take place. You played a vital part in this scheme.’
Jailing her for 16 months, the judge said: ‘There is nothing I have seen in the pre-sentence report or in the medical evidence before me which gives rise to circumstances in which I should suspend the sentence of imprisonment.’
