The two women were refused the treatment due to a government regulation that effectively denies it to women without a male partner, said the group, which advised the couple in the case.
The couple argue that denying them the treatment was discriminatory and breached their reproductive health rights. A court heard their case on Monday and is due to give a ruling at a later date.
They began the treatment in 2014 but say the hospital told them in November that they were excluded from the programme under an order from the health ministry issued the previous month, Women's Link Worldwide said.
The rights group said the ministry granted the treatment only to couples who had spent 12 months unsuccessfully trying to have a child through sexual intercourse, excluding lesbian couples de facto.
The hospital later told the couple they had reassessed their case and they could resume the treatment but the women pushed ahead with their lawsuit, the group said.
They sued "so that no other woman who opts to be a mother will be discriminated against by the public health system," said their lawyer Carmen Miguel in a statement.