According to reports, Rebecca Roberts and her partner Rhys Weaver had struggled with infertility issues for years.
The couple opted for fertility medications to enhance their chances of bearing a child.
Then, Roberts discovered later that she was pregnant — and, while pregnant, got pregnant again.
She took to her Instagram page to express her dismay at the development which she said was a miracle.
READ ALSO: Tepa SHS student stabs shopkeeper to death over polythene bag
"This is not supposed to happen at all, especially in humans," Roberts said.
The case of the happy woman who reportedly gave birth in September last year is not common.
Known as "superfetation", Roberts’ case happens to be record-breaking because her three-week interval is the longest time between conceptions. Past cases include women who conceived again 10 days after becoming pregnant the first time, reports say.
Superfetation occurs when a second egg is fertilised by sperm and implants in the uterus after another fertilised egg has already done so.
It's nearly impossible, though, because when someone gets pregnant, their bodies release hormones to prevent ovulation or the release of another egg. Their bodies also block sperm from entering the cervix and release hormones to inhibit a second fertilized egg from implanting in the uterine wall.
Health experts say all three of those mechanisms have to go wrong for superfetation to occur, usually due to fertility treatments.
Superfetation comes with risks since the fetuses are growing at different stages of the pregnancy.
Insider.com reported Roberts as having said that her fertility medications influenced her ovulation, allowing her to ovulate again three weeks after her first conception.
Doctors had told her that her younger child, Rosalie might not survive but that prediction failed, fortunately.
"What came after getting pregnant was just such incredible hard work," Roberts told GMA. "It wasn't all happy and rainbows like you expect pregnancy to be. It was quite scary."
She gave birth at 33 weeks prematurely because of a problem with Rosalie's umbilical cord that prevented her from growing properly, according to reports.
Noah, her son weighed four pounds, 10 ounces, while Rosalie weighed two pounds, seven ounces and they both spent time in the NICU due to premature birth.
"Our babies are absolutely amazing. They are really special and I just feel so happy that I'm their mom and I get to share this amazing journey with them," Roberts said on Instagram after being reunited with her lovely babies.