Superfetation; an extremely rare occurrence

in hive-196387 •  last month  (edited)

Pixabay CCO

Just a few weeks ago on one of those lazy mornings you would just want to be on the bed all day, I woke up and picked my phone to chat with some friends (on a WhatsApp group) as usual. We were having fun until someone dropped a question “Is it possible to impregnate a woman that’s already pregnant?” At first, much more people thought this was just another joke from the person that dropped the message until one of the married people in the group affirmed the point. …and that was how it all began! Normally, I would expect some thunder, lightning and some dark skies to back the last statement but I see nothing. Lol. Let’s see what I found.


Pixabay CCO

[1] Superfetation is the occurrence of a second conception during pregnancy leading to the development of two embryos in the uterus. This means that apart from having fraternal twins, we can also have twins that are older than each other and depending on the difference between the time of conception may not be delivered together. Although some times, both babies would likely be delivered at the same time, I’ve heard of a more surprising experience when a woman was delivered of a baby and went back into labour again two weeks after the first baby was born. Funny right? I laughed too when I heard of it.

As interesting as the case may sound, [2] Superfetation is extremely rare and had only about 10 documented cases in humans around the world as of 2017. Yes, lower animals like kangaroos, panthers, fishes and of course, rats experience it too maybe even a bit more often than we humans. Who knows? Even Dr Brad Armstrong, the couple’s obstetrician, admitted he had to google it to find out.

How does this happen…?

Pixabay CCO

[3] Usually, pregnancy is accompanied by a host of hormonal changes like hyperthermia, dehydration, skin changes, hyperpigmentation, changes in sense of balance, metabolic changes, nausea, vomiting and of course, ovulation and cervical changes. Of all these changes, only a few are important to this topic; the ovulation changes and the cervical changes because these changes are the ones that prevent occurrences like superfetation from happening. Let’s have a brief talk!

[4] Ovulation is the release of secondary oocyte ovarian cells when the ovarian follicle ruptures. Err…Skip all of that! Ovulation is simply the release of egg or eggs from a woman’s ovary or ovaries. Usually, this ovulation process is what makes eggs available for fertilization by the sperm. This is what makes it possible for women to get pregnant and this process under normal circumstances halts at conception. So for Superfetation to occur, it means that the ovulation changes did not occur and eggs were released after conception and of course, there was sexual intercourse to account for the sperm that fertilizes the egg leading to a second conception.

Cervix is a cylindrical neck of tissue that connects or links the vagina and uterus. The cervix starts forming a [5] mucus plug the moment a fertilized egg is implanted in the wall of the uterus. The cervix mucosal cells pump mucus which seal off the cervical canal during pregnancy. This mucus plug only begins to thin out when labour is fast approaching. So in this case, it means superfetation can only occur before the cervical canal gets completely sealed which might limit the time frame to a few days or maybe a week after the first conception.

Another thing is that since both pregnancies are different, there would be a need for another implantation which makes it double implantation of eggs. Something like what happens with di-zygotic twins only that this is a product of separate sexual intercourses which are probably a few days apart. Usually, a second implantation would only be possible with the help of some hormones. Now, you’d agree with me that the chances of all these occurring at the same time is minute and this explains why it is extremely rare.

I designed this

Well, if you followed this write-up, at least you’d be able to say that the preventive measure should be not having sex with one’s partner days after conception but let me ask if there’s a way to even know one is pregnant few days after sex? If you have sex and begin to feel dizzy immediately or let’s 2-3 days afterwards, I can confidently tell you it’s not as a result of the last sex you had. Something else is probably wrong with you and you need a medical check-up, lol. Since the earliest symptoms of pregnancy don’t show up until after weeks, it is good to mark out this option from the preventive measures. However, if you undergo a test and find out you’re pregnant, then this should work. But really, even if you don’t abstain from sex, there’s only a little chance you’d get pregnant again.


Sometime in 2017, a surrogate mother discovered she was carrying two babies and in fact, one of them was her biological son. She had conceived a few weeks after the first conception. Now, she was carrying two babies just as Superfetation but these babies have different fathers.

[6] So just like Superfetation, Superfecundation is also a result of double pregnancies, different intercourses but different fathers. So a proper definition of Superfecundation would be ‘the fertilization of a second ovum in the same cycle by sperm from separate intercourse and parent.

Most people don’t seem to get the gist as they mix up both of them. But you can always have this in mind “All Superfecundation are Superfetation but not all Superfetation are Superfecundation.” This holds true because Superfetation is not concerned with the paternity of the children but Superfecundation is.

Conclusively, I hope I’ve been able to introduce the concept of getting pregnant while pregnant? It was fun! Now, let’s get some rest!

Till I write again,


[4] Ovulation
[5] Mucus Plug
[6] Superfecundation

Further Reading:-


Twins and Twinning

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Fascinating, but file this with all the things that might happen...
Just another example of how nature plays favorites. Some women cannot produce a child, even with all the help science may offer. And then there's superfetation and superfecundation :)

This was a great read!

Well, what can I say? This life is not really balanced. Things are not evenly distributed. Some have more than they'll ever need, some don't even have what they need for the moment. That has always been the case, I don't think there's anything we can do about that.

I'm happy you dropped by.

And you are back with a bang! Congratulations for posting again after a while and I hope this time, you will resume regular posting.

That being said, this is quite ẹyẹ opening and educating...thanks for this.

Also, do dizygotic twins always come from different fathers? I thought they are just different eggs ferterlized by different sperms. The sperms can be from the same person, of course. Perhaps I've been wrong all these while?

Lol... Well, we are out of school now so I'm free until we resume. So for now, I'll try to keep up with regular posting.

Dizygotic twins are just the regular type of twins we call non-identical twins. They are usually a product of different sperm and egg cells which does not mean it has to be different intercourses. Everything as monozygotic twins applies expect for that two eggs and sperm cells are involved. So no, you haven't been wrong all along. Since it's dizygotic twins, they'll have the same father. The moment they have different fathers, it ceases to be dizygotic twins, it becomes superfecundation.

What a title! I didn't even know that word was existing (at least I didn't think about it). Thanks for this nice come-back post :)

Look who came late to the party, Sir Lemouth :) Thanks for the comment, it means a lot.

I am late, but I came... Last week was really tough for me... Please apologise my late arrival ^^

I can understand your lateness and I can only applaud the wonderful work you're doing around here. Like I said, the comment means a lot, :)

Your replies are appreciated too ^^

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