A woman in Bangladesh with two uteruses gave birth to twins this month, less than four weeks after delivering another child.

BBC News reports Arifa Sultana, 20, gave birth to a premature boy in late February, according to her gynecologist. Twenty-six days later, after she went to the hospital with pain in her stomach, doctors discovered she was still pregnant and delivered a healthy set of twins -- a boy and a girl -- via Caesarean section.

How could Sultana not know she had two simultaneous pregnancies? Her doctor said Sultana and her husband were never able to afford an ultrasound before her first delivery.

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The Mayo Clinic says "a uterus starts out as two small tubes. As the fetus develops, the tubes normally join to create one larger, hollow organ — the uterus. Sometimes, however, the tubes don't join completely. Instead, each one develops into a separate structure."

The condition of two uteruses can increase the risk of premature birth or miscarriage, the Mayo Clinic said.

All the children are healthy, BBC reports, but Sultana and her husband are concerned about their financial situation and childcare. Her husband earns $95 per month.