UNRAVELING THE BIOLOGY BEHIND HETEROPATERNAL SUPERFECUNDATION- twins with different fathers in a pregnant woman

This is basically what happens when a man releases millions of sperms in a female. Having said all the above, here comes the big question.

Why then heteropaternal superfecundation?

The explanation given below has not been fully accepted around the world as the major or conclusive cause of HS. Though the reason might seem convincing enough, but it is not conclusive. A lot of factors come into play when dealing or trying to use human embryo as an experiment. The real mechanism of HS is still not well understood up till date. Read along and you will find out why.

HS mainly occurs when two different men are responsible for a pregnancy in a female fraternal thus resulting to fraternal twins.

Since the female body system is programmed to inhibit or stop further fertilization of eggs by sperm, how then is it possible for a woman be pregnant with fraternal twin babies after having sex with two different men?

The reason is this, when a sperm is released, this sperm can actually remain viable or active and can stay for about four to five days in the oviduct of the female waiting or scanning and looking for an egg it will fertilize, failure to find an eggs leads to its deterioration and death. The egg on the other when released during ovulation only has about twenty (24) to forty eight hours 48 hours to stay after which it begins to disintegrates.

This invariably means that the total time the sperm can stay in the female is about 5 -7 days. During this period, a lot of things can happen when things go wrong with the normal physiologic system involved in conception. If peradventure the woman who has slept with a man gets pregnant and then after some days sleeps with another man, provided the normal mechanism of conception I earlier explained above is not in places or not in normal state, HS is likely to occur. Although this condition is a rare one, but the fact remains that it is real. HS can either occur during normal sexual intercourse or during the process of artificially insemination, a situation where the egg of a woman and the sperm of a man is artificially fertilized in the laboratory and then the zygote formed is transferred into a woman who is unable to conceive a baby.

^{Steps in IVF, wikicomons by OpenStax College under CC BY-SA 3.0}

This procedure is also known as in-vitro fertilization (IVF). During the process of IVF, it is very possible that more than one fertilized eggs are inseminated into the woman, thus resulting to different implantation at different sites.

Assuming the couple had sex before the woman is artificially inseminated with an in-vitro fertilized egg (egg fertilized in the laboratory inside a tube), provided the sperm released by the man is still viable i.e. its duration of stay inside the uterus is still within 5-7 days, there is a high chance of one blastocyst to be implanted inside the womb of the woman, thus resulting to one embryo biologically from the husband and another embryo from the IVF.

Documented cases so far indicated that the likelihood of heteropaternal superfecundation is associated more with invitro fertilization.

Why do some twins differ ?

^{wikicomons by National Human Genome Research Institute under CC BY - SA 3.0}

Ever wondered how twins either identical or fraternal twins are formed? In the case of identical twins, it occurs when a single sperm fuses with an egg, the fusion results to splitting of the egg into two identical forms while in the case of fraternal twins, two separate eggs are fertilized by different sperms but from one man, this case is as well known as homopaternal superfecundation.

If you reason along with me, what this invariably means is that heteropaternal superfecundation is actually a type of twining resulting to twin babies that are not identical. In the case of heteropaternal superfecundation, the babies as well are not identical but the difference here is that, they are from different fathers.

Reported cases of HS

A lot of cases have been reported so far about this condition, the first case of heteropaternal superfecundation was reported in 1982. The twins had different colour of skin and further investigation revealed that they were both from different fathers.
A more recent case that occurred in April 2016 is that of a female by name Jessica Allen who decided to play the role of a surrogate mother. She was artificially inseminated through IVF,

^{wikicommons by Martaff under CC by-SA 3.0}

after a period of six weeks of been pregnant, never did it occur to her that she was carrying two babies in her womb. Guess what, these babies were actually fraternal twins and the most shocking news was that the babies were of two different fathers, one from her husband and one from the artificially inseminated.

I know the question now is- how did they know that the babies were of different fathers? The answer is quite simple, the DNA test conducted on the babies revealed the whole information. Science has gone far beyond what we see here.

The father’s DNA result only matched with one of the baby while the other matched with that of the artificially inseminated.

Barrier to further research on Heteropaternal Superfecundation

Despite the few explanations given by various medical experts around the world, it is still not very clear how HS occurs. Most of the explanations given are not concrete enough to ascertain the actual cause of HS but they are also factors to consider. According to the report from American journal of obstetrics and gynaecology one of the limitations to further research about this occurrence is due to the ethical issues surrounding human embryos.

Human embryos are treated as humans in general and as such, cannot be subject to unfair laboratory experimentations. This is similar to the case of cloning if human beings. Were it not for the strong intervention of regulatory bodies like WHO and other human right organizations, thousands of clones would have been on the streets.

These embryos are basically humans yet to be formed, they are divine creatures, and they have that same intrinsic value as being called humans. Even though most research are targeted at discovering the cause, proffering solutions that will alleviate the sufferings of humans; the inalienable and fundamental human right -right to life remains non-negotiable. This is the major barrier impeding research associated with embryos. This is also backed up with the Universal declaration of human rights. Art. 3 of this law states that no one or human may be subjected to torture or to inhuman or degrading treatment or punishment. Since the embryo is under the ambient of being regarded as human.
An article published by the Electronic Journal of Comparative Law in Netherlands, shows that they have a bill that protects the right of the embryo as human. According to this bill,

the embryo is a cell or a connected aggregate of cells with the capacity to develop into a human being thus, shall not be in anyway maltreated.

There are a lot of laws prohibiting the use of embryo as an experiment and this had made in-depth research into the cause of HS very difficult in humans. All the laws are in one way or the other ensuring that the dignity of man is protected, be it embryo or full grown being.

Conclusion

HS is quite rare but the truth remains that it does exist. The possibility of a woman conceiving twice in one sexual cycle i.e. one menstrual cycle is real. As long as two eggs are released after ovulation, if the woman sleeps with two men, there is a very high chance of Heteropaternal Superfecundation occurring. This is possible because sperms from the two different men can fertilize two different eggs.

All thanks to my ingenuous colleague for revealing such a wonderful topic of discussion.

Thanks for reading.

References and further reading

•The society of obstetricians and gynecologists of Canada

•wikipedia-superfecundation

•twins with different fathers

•cnn-news

•forensic science journal

•A review of the mechanisms and evidence for typical and atypical twinning

•Key ethical issues in embryonic stem cell research- parliament of Australia

•Rights of a human embryo

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