Bui Thi Hien, 33, in Nam Dinh Province, and Khong Thi Lan, 34, in Yen Bai Province are being investigated for "organizing surrogacy for commercial purposes."

According to investigators, Hien had used social media to source couples eager for babies and young, educated women like college students wanting to act as surrogates in exchange for money.

Hien would accompany successful candidates to hospital for embryo implantation, registering them as single mothers.

Hien charged VND830-850 million ($36,000-37,000) per baby born, paying each surrogate VND250 million.

Lan was charged with caring for surrogate mothers during their pregnancy at Hien’s place in Nam Dinh.

For this job, Lan received VND10 million per woman.

When busted, Hien and Lan had been looking after nine pregnant mothers.

Vietnam legalized surrogacy in 2015 to benefit infertile couples, but only on charity basis, and couples can only seek help from family members. Commercial surrogacy is punishable by up to five years in prison.

The country's first baby born to a surrogate mother was in 2016 in Hanoi. The mother of the girl was unable to conceive after 18 years of marriage due to congenital abnormalities.