STORY: It was three weeks since Annaelle gave birth to twins in Democratic Republic of Congo's capital Kinshasa.

But the 16-year-old still hadn't left hospital.

Unable to pay her medical costs, she was effectively being held hostage.

Then entered a woman Annaelle had never met before - to hand doctors $130 and settle the bill.

This is Grace Mbongi Umek - a businesswoman who has made it her mission to free new mothers trapped by their maternity debts.

"As far as my objective is concerned, it's clear: I want this to stop. I want women in my country to give birth in good conditions and not be held hostage because they cannot pay."

Like many countries in sub-Saharan Africa, Democratic Republic of Congo has no universal health coverage.

While President Felix Tshisekedi's government is ratifying a law to make health services free for the vulnerable, the minimum $40 required to give birth in a health facility is out of reach for many.

According to the World Bank, more than 60% of Congo's population lives on less than $2.15 a day.

Cash-strapped hospitals say they are forced to keep patients until they've paid in full.

"So I said to myself, why not help these women have their fundamental rights, the right of a woman not to be detained in a maternity hospital just because she's given birth?"

Umek, who owns shares in several security companies, set up a foundation in 2017 to help mothers with unpaid medical bills.

She says she donates up to $3,500 a month.

At Kinshasa's Bethesda hospital, Annaelle and two of her roommates uttered their thanks and wrapped up their babies.

Unburdened by debt, they can finally take their children home.