Rebecca Roberts, a 39-year-old British woman from Wiltshire, had an unusual pregnancy, giving birth to twins conceived three weeks apart. When she gave birth, it became apparent to the doctors that the children, a boy and a girl, were not of the same «generation» as they varied in height and weight.

Initially, during pregnancy, the ultrasound had only revealed a fetus in her womb. However, she later found out that she was expecting twins. The children were born in 2020 with a considerable weight difference: the girl weighed 1.2 kilograms while the boy weighed 2 kilograms. This situation intrigued the doctors because it did not correspond to a typical twin pregnancy.

After further study, specialists discovered that a very rare phenomenon had occurred: superfetation. This means that Rebecca got pregnant a second time when she was already three weeks pregnant. Therefore, baby Rosalie was conceived with a gap of three weeks.

This case, according to specialists, would be the fourteenth of its kind in the world. Rebecca was taking an infertility drug prescribed by doctors, which experts say may have contributed to the occurrence of superfetation. They explain that after the first successful fertilization, the eggs continued to mature. The children stayed in the clinic for a while to gain weight but were healthy and developed normally thereafter. This unusual pregnancy highlights just how complex and unpredictable human biology can be.