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For many years, there were certain myths about getting and being pregnant that were said and even taught. One of those myths is that you can’t get pregnant during your period; another, that you can’t get pregnant when you’re already pregnant. While these things don’t happen very often, there are cases around the world where they have. And we’ll explain how one of them occurs right now.

How It Happens

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Scientifically, this process is known as superfetation, and this is how it happens. When a woman is pregnant, her ovaries usually stop releasing eggs because, well, an egg has already been fertilized. That fertilized egg should then become the primary focus of the reproductive system. But that doesn’t always happen. Sometimes, the ovary doesn’t stop releasing them, making these eggs perfectly available to also become fertilized. And when they do, it results in superfetation.

How Easy Is Superfetation

When one thinks about how easy the entire process sounds, it should stand to reason that this would happen all the time. But there’s way more to it than what we’ve explained. There are certain measures that the body takes to ensure that the chance of this happening is extremely slim. But scientists have noticed that it is more likely to happen to women on hormone therapy or those going through IVF.

Preventing Superfetation Part 1

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For one, a woman’s hormones during pregnancy are very high, allowing a mucous membrane (which protects the fetus) to form, blocking out intruders, such as sperm. The sperm would have to make it through this barrier and to the egg to fertilize it, all within a very short time frame.

Preventing Superfetation Part 2

Even if the sperm does make it to the egg and fertilizes it, this fertilized egg would have to find its very own spot in the uterus to make its home for the next several weeks. And chances are incredibly slim that that would happen, especially because there’s already an egg already being housed in the walls of the uterus.

The Dangers

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As amazing as this process sounds, there is a high chance that it could harm one or both of the babies. Enough cases haven’t been documented, but scientists believe that the mother could have a difficult pregnancy, that one baby could be born premature (depending on how far along in the pregnancy superfetation occurs) and more.

But Are There Actual Cases

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There are at least three documented cases of his happening. In 1999, a woman gave birth to two babies, one which was 39 weeks old and the other, 35. In 2005, a woman who had undergone IVF and was pregnant with twins found out that she was also having a third child, whose fetus was much younger than that of her twins. A third woman had this happen to her, but her margin was much shorter; there was a time period of ten days between each fertilization.