"Many girls believe their bodies are purging evil spirits, or that they are injured once a month; this is a shame-filled reality they quietly endure," she said.
"All of these factors perpetuate the cycle of poverty and stunt a young girl's dream for a more prolific future."
The United Nations advocate explained that if a girl misses school every time she gets her period, she will end behind her male classmates by 145 days.
If they end up dropping of school, Meghan noted that they are "increasing their subjection to dangerous work, susceptibility to being victims of violence, and most commonly, being conditioned for early childhood marriage."
Meghan stressed that in order to remedy this problem, girls need Menstrual Hygiene Management (MHM), access to toilets and sanitary pads.
During her trip, the actress shadowed women who manufacture sanitary napkins and sell them within the community, and she noted that the women's work is also opening the "dialogue of menstrual hygiene in their homes".
"Beyond India, in communities all over the globe, young girls' potential is being squandered because we are too shy to talk about the most natural thing in the world," she said.
"To that I say: we need to push the conversation, mobilise policy making surrounding menstrual health initiatives, support organisations who foster girls' education from the ground up, and within our own homes, we need to rise above our puritanical bashfulness when it comes to talking about menstruation."
Last year, Meghan travelled to Rwanda for World Vision's clean water campaign, and she credits her parents for her philanthropic nature.
"Both my parents came from little, so they made a choice to give a lot - buying turkeys for homeless shelters at Thanksgiving, delivering meals to patients in hospice care, donating any spare change in their pocket to those asking for it, and performing quiet acts of grace - be it a hug, a smile, or a pat on the back to show ones in need that they would be alright," she wrote on her lifestyle blog The Tig last October.
"This is what I grew up seeing, so that is what I grew up being: a young adult with a social consciousness to do what I could, and to, at the very least, speak up when I knew something was wrong."
Over the weekend, Meghan joined Prince Harry in Jamaica to attend the wedding of his childhood friend Tom Inskip, who said 'I do' to Lara Hughes-Young.