A British woman has become one of few to conceive while already pregnant.

Rebecca Roberts, age 39 years old from Wiltshire, England, was diagnosed with Superfetation at 12 weeks of pregnancy.

According to the World Health Organization (WHO), Superfetation is an extremely rare condition where a woman can get pregnant whilst being pregnant.

The news however was beyond the couple’s belief, as the woman had been struggling with infertility for years. Also, the doctors were reserved to confirm the diagnosis until several tests were conducted.

The condition is so rare that there are only 14 reported cases worldwide.

At only 33 weeks of pregnancy, the doctors noticed that the second fetus, a girl, was not developing normally, a development that led to conduct a C-Section.

On September 17 last year, Roberts gave birth to two babies a boy and a girl, whom the couple named Noah and Rosalie,

While Noah was a fully grown baby boy weighing 4 pounds, 10 ounces, his sister Rosalie visibly smaller, weighing only 2 pounds, 7 ounces.

She spent 95 days in the hospital before she was allowed to go back home before Christmas.

The toddlers will be seven months old next weekend even though there are noticeable developmental differences between them.

According to Roberts, Rosalie is catching up with Noah very fast.