The major cause of this movement was a general movement towards reform that was going on in the United States during the 1830s and 1840s.
During the 1820s and 1830s, the US economy and society were changing. The economy was moving away from subsistence farming and barter and more toward a "commercial revolution." This caused great upheaval in society. These changes, along with the ideas of the Second Great Awakening, led to the idea that society could be changed and perfected.
With this idea came many reform movements meant to make society more perfect. These included movements such as abolitionism, a push for improved education, temperance, and many others. Many of the leaders of these movements were women who were coming to have more time for activism because of the economic growth caused by the commercial revolution. Many of these women eventually moved to the idea that a women's rights movement would be an important part of reform.
So, the changes to American society brought about by the commercial revolution and the Second Great Awakening are largely responsible for the women's movement.