Woman gave birth to twins after falling pregnant with second baby while already expecting

In case you thought already being pregnant was a surefire way to make sure you don't get pregnant - again - one woman from the US is here to prove you wrong.

Odalis Martinez De La O was 26 when she got pregnant with her first baby on the last day of her menstrual cycle, but she wouldn't even have had chance to register the first baby when she found herself with another bun in the oven.

Naturally, the mum was 'shocked' when she went to the doctors in 2021 and learned she was pregnant with twins, but Odalis, a programme manager from California, was even more surprised when the ultrasound doctor explained that the babies were ‘measuring differently’ and had been conceived at different times.

“I was definitely shocked," she said about her visit to the doctors, adding: “Firstly, because it was twins, and secondly, processing the fact that they were conceived five days apart. I've never really known how twins work so I didn’t know that could happen – it was a really great surprise."

Her unusual pregnancy came about as a result of an 'extremely rare' phenomenon called superfetation, which relies on a number of moving parts.

It begins with the mum releasing two eggs instead of one during her cycles. Once that has happened, both eggs must be fertilised by different sperm, after which they both need to implant in the womb.

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But, superfetation only occurs if all three of these factors take place.

And this is exactly what happened with Odalis. After previously having experienced a miscarriage, the mum and her husband were over the moon to learn they would be welcoming not just one, but two children into the world.

"Getting the news that it was two was beautiful," she said. "All my family were asking how that can happen, we were all so shocked. It’s good information to know about. I’m telling all my friends to be careful now!”

Odalis and her husband, Antonio, welcomed their children Lilo and Imelda via caesarean section into the world on 10 August, 2021.

The babies aren't identical, though Odalis admitted they 'have some days where they look extremely alike'.

"But if you ask people who don't see them everyday, they say they look the same," she added.

The unusual gap between the conception of Lilo and Imelda continues to surprise people who have been learning about Odalis' story on TikTok, with many admitting they had no idea superfetation was possible.