When the Company of 100 Associates began their settlement scheme, their plan of recruiting only families proved to be too costly, so instead they signed on single men; tradesman and labourers; who would be indentured for three years. However, this meant that more than 80% of the colonists were men, so even if they decided to stay at the end of their term, there was little hope of them starting a family, unless they chose a Canadian girl. But, since her family would never allow her, or her children, to leave their village; the company directors needed to avoid this from happening.

So instead, they began recruiting "marriagable young girls", who would first sign a contract in France and then be given passage and a small dowry to become the wife of a Quebec settler. You might wonder why these young girls (many under 16), would risk the dangers and hardships, which by now most of France were well aware of; but believe it or not; for many it was the best option.

At the time, marriages were arranged, so if the girl's family did not have the means to provide a sutable dowry, her only option was to become a nun, if she was Catholic; or marry beneath her station. In the case of the young Filles a Marier, though a marriage contract must be signed before departure, she had every right to refuse the union, once she met her husband-to-be. As a matter of fact, many of them did just that, and were provided safe passage home.

Source: oocities.org/ weallcamefromsomewhere/Kebec/filles_marier