Story highlights India has become a Mecca for foreigners seeking a surrogate mother to gestate their child

India is one of the few countries that allows commercial surrogacy, where costs are low

Critics say the practice takes advantage of poor women and is akin to "organ sale"

Surrogates interviewed say the up to U.S.$8,000 received rescues them from a life of poverty

Madhu Makwan asks a reporter to translate a card in English she received from a Canadian family for whom the Indian laborer spent nine months gestating their son for them.

The letter reads in part: "Without your help and sacrifice, we would not be able to have our family. Please know we will tell him about you and how special you are to us. We will never forget you, you will always be in our hearts."

Makwan delivered the boy two weeks ago. "Of course I feel bad -- I kept the child in my womb for nine months," she said. "But she needs a child; I need money."

Surrogacy in India is booming, thanks to the low cost of the procedure, availability of surrogates in the world's second most populous country and the fact that India is one of the few countries in the world that allows commercial surrogacy.

In one hostel in Anand -- a small city known as the "milk capital" of India in the far western state of Gujarat -- there are 50 surrogate mothers living together, each who will earn around U.S.$8,000 for carrying a baby.

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"It's a lot of money," said a woman who identifies herself as Manjula. "For people like us who have never seen money, it's a lot of money."

This is the second time Manjula -- a 30-year-old who has a son and two daughters of her own -- has carried a child for profit. Before surrogacy, she and her husband used to earn less than $2 a day working in the fields. "The first time I came, I made a house," she said. "Now I have come for my daughter. I have to educate her, I have to get her married."

"I want to teach my daughters computers; I have to educate them -- get (them) married to a nice boy," she added.

The number of skilled doctors has made India a global Mecca for couples seeking someone to carry their baby for them. At this hostel, all the women are under the care of Dr. Nayana Patel. She began caring for surrogates in 2003, when she helped a grandmother who was carrying twins for her daughter.

"That's when I started commercial surrogacy because not everyone is lucky to have a mother or a sister or a friend to carry their child," she said.

"The surrogate is getting the life that she dreamed of, because otherwise she could not get this kind of money or change the life for her husband, her children, get a house, educated her children," said Patel, who has delivered close to 700 babies from surrogates for 580 couples since 2004. "And the couple could never have had a child if the surrogate had not helped them. So -- the ultimate result is a baby has come into this earth, which is beautiful."

India has now taken steps to regulate the industry. It's banned foreign same-sex couples and single parents from hiring surrogates. A new proposal would require mothers be aged between 21 and 35.

Patel has had "lots of inquiries from same sex couples but we have never done it. Not for any other reason, this being a small town, people are not aware of all this and for the surrogate to be introduced to same sex couple would be too much, I felt."

Critics call India's surrogacy clinics baby-making factories. "Commercialization has led to a lot of financial exploitation of these women," said Ranjana Kumari, a women's rights activist and director of the Center for Social Research in New Delhi.

Although surrogates interviewed by CNN in Anand say they get as much as U.S. $8,000, Kumari said research by the center shows that promised cash from surrogacy clinics often fall short -- sometimes being paid as little as U.S.$800. "So its not really a profitable business as is presented," Kumari said.

"If someone really has to opt for the child, somebody's friend should offer a womb, somebody's relative should offer the womb. Why it has to be the poor woman? It's like organ sale," Kumari added.

Surrogates say locals also look down on the practice. "People in the village think it's a dirty thing. Old people in the village, they don't have good thoughts," said Manjula. "For me, Dr. Patel has done a good thing."

Surrogate mother Madhu Makwan says the service has completely changed the fortunes for herself and her family. Asked what she would say to the Canadian parents who rented her womb: "I'd say thank you. I don't know how to say anything else in English!

"I've got a chance now to make my life," said Makwan, wiping tears from her eyes. "God has been kind."