Markle, 35, who visited India in January as an ambassador for World Vision, wrote for the first time about her experience in India with the young women she met there.
She shared a statistic that when a girl misses school in India due to her period, "cumulatively that puts her behind her male classmates by 145 days."
"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," Markle wrote in "How Periods Affect Potential."
She continued, "We need to push the conversation, mobilize policy making surrounding menstrual health initiatives, support organizations 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.”
Markle was congratulated by fellow actress Priyanka Chopra on Twitter for her bravery in addressing the often-taboo subject in India that more than 100 million girls face. Chopra, a former Miss World, is one of the most admired actresses in India and she now stars in "Quantico" on ABC.
Markle described how many young girls embarrassed by their period avoid going out in public and sacrifice their schooling because they don't have proper access to sanitary napkins and tampons.
"All of these factors perpetuate the cycle of poverty and stunt a young girl's dream for a more prolific future," Markle noted in the essay.
The "Suits" actress also released a poem on her Instagram and Twitter accounts reminding women about their value and worth. The poem, by Nayyirah Waleed, includes the verses, "I will tell you, my daughter of your worth, not your beauty, everyday (your beauty is a given. every being is born beautiful), knowing your worth, can save your life."
Markle and Harry have reportedly spoken about both wanting children. The choice by Markle to post an inspiring poem referencing a daughter was viewed and commented on thousands of times on social media.
Markle, whose relationship with Harry has been growing increasingly serious, spent last week in Jamaica with Harry, the fifth-in-line to the British throne, for the wedding of one of Harry's closest friends.