Sex selection – enabling couples select the sex of their children – has been described as an important aspect of Assisted Reproductive Treatment (ART). However, the reasons for sex selection could be medical, social or personal. In this interview with CHIOMA UMEHA, Nordica Medical Director, Dr Abayomi Ajayi, explains how genetics is assisting couples to choose the babies they want perfectly.
Could you explain what sex selection means?
Sex selection refers to the practice of using medical techniques to choose the sex of your baby. Sex selection’ encompasses a number of practices, including selecting embryos for transfer and implantation following in vitro fertilisation (IVF), separating sperm, and selectively terminating a pregnancy. Sex selection is particularly relevant to a discussion on gender and genetics, because genetic technologies and services are used to choose one sex over the other. Sex selection has a wide range of ethical, legal and social implications. A significant ethical concern is that sex selection for non-medical reasons will reinforce discrimination, particularly against women.
There are three core motivations for engaging in sex determination and sex selection. It could be for medical reasons such as preventing the birth of children affected or at risk of X-linked disorders. For family balancing reasons, couples choose to have a child of one sex because they already have one or more children of the other sex. And gender preference reasons – often in favour of male offspring stemming from cultural, social and economic bias in favour of male children, and as a result of policies requiring couples to limit reproduction to one child, for instance in China.
What are some of the ethical issues that could be raised by sex selection?
Sex selection for non-medical reasons raises serious moral, legal, and social issues. The principal concerns are that the practice of sex selection will distort the natural sex ratio, leading to gender imbalance and reinforcing discriminatory and sexist stereotypes towards women by devaluing females. In some countries, such as India and China, it is commonly known that the practice of sex-selective abortion has resulted in distortions of the natural sex ratio in favour of males.
In addition, there is concern that sex selection involves inappropriate control over non-essential characteristics of children and may place a potential psychological burden on, and hence cause harm to, sex-selected offspring.
There is a belief that the time of intercourse determines a particular sex produced. How relevant is your Assisted Reproductive Therapy’s (ART’s) genetic to sex selection?
People have said all kinds of things about what couples should do and what they shouldn’t and most of them where not found to be true, this validity is based on the fact that specialists know that in the sperm setting (the chromosomes), one is higher than the other one.
That is why they say if you have sex around the time that your wife is likely to ovulate, that you are likely to have a boy. That is because the sperm carrying the boys are faster and are not as heavy as the sperm carrying the girls, so if you have sex then, they are the ones that will get to the egg.
But, the problem is who can tell when the wife is going to ovulate? So, that is the problem with that. Most of the things that are said are like midwife tales – they have not been proven in real life. That is why we say the scientific way for sex selection is the best and gives guarantee. And there are only two methods- sorting the sperm or pre-implantation genetic diagnosis (PGD), as well as pre-implantation genetic screening (PGS).
What are the differences between the PGD and PGS?
Genetic technologies for sex selection are available depending on the type and timing of sex selection and whether or not it occurs in sperm or embryos. The development of effective prenatal diagnostic tools, such as chorionic villus sampling (CVS), amniocentesis and ultrasound in the 1970s made prebirth gender identification a reality. In the early 1990s, preimplantation sexing of embryos for transfer following in vitro fertilisation (IVF) was developed, enabling highly reliable preconception sex selection. More recently, sperm separation by flow cytometry has enabled a less invasive method of sex selection. So, sex selection can be done through one, preferti-lisation; two, postfertilisation and prefertilisation; and lastly postim-plantation.
Sex selection by sperm sorting or flow cytometry enables the separation of X- from Y-chromosome-bearing sperm due to slight differences in weight (whereby X and Y-bearing sperm have a DNA difference in content of approximately 2.8 percent).
Sexed sperm are then used to fertilise the egg, either in vitro or in vivo (for example, through artificial insemination techniques). Preconception sex selection methods do not destroy embryos or foetuses and are not as invasive as prenatal or preimplantation sex selection.
Can you explain further?
For postfertilisation and pretransfer, as of today, the principal reliable techniques for sex selection are limited to post-fertilisation methods. The technique of preimplantation genetic diagnosis (PGD), employed in assisted reproduction before the transfer of embryos fertilised in vitro, enables blastomere biopsy of one or more cells from a developing embryo at the cleavage or blastocyst stage to ascertain sex. In contrast to sperm sorting, PGD provides nearly 99.4 per cent accuracy for selecting either sex.
Still, because PGD requires in vitro fertilisation (IVF), the practice of sex selection via PGD has been primarily used by persons trying to avoid having children with X-linked disorders. So preimplantation genetic screening (PGS) comes in. For example, approximately 50 per cent of male children born to women who are carriers for haemophilia will have this condition.
In order to ensure that offspring do not have this condition, some women at risk of transmitting haemophilia choose not to transfer male embryos following IVF.
Well, for postimplantation, sex selection through prenatal diagnosis followed by selective abortion has existed since the 1970s.
And lastly, established postimplantation techniques to determine fetal sex during pregnancy include ultrasound, chorionic villus sampling (CVS) and amniocentesis. In addition, karyotyping of fetal cells provides information about fetal sex.
These postimplantation methods of sex determination, followed by abortion between eight and twenty weeks gestation, represent the most commonly used methods of sex selection.
What are the success rates and the link to our cultural background?
PGD is still IVF. When you are talking about success rate, the fact that we can get a particular sex through sperm sorting is about 86 percent, for the embryo to be a particular sex is about 86 percent, that you can get from PGD is about 99.4 per cent.
What we can do to increase the success rate is to do PGS not only just taking the sex but to screen the embryo to make sure it is normal. So what we try to do is that at Nordica Fertility centre, we don’t separate the process of PGD and PGS. We advise clients to do the two together so that the chances of getting a baby from the process will be high. This is because there is no point transferring an abnormal embryo.
With PGS, after doing PGD, we are able to see that this particular embryo is normal and all the chromosomes have been seen and the embryo can become a baby. PGD is a little bit different from PGS, despite the fact that the procedure is the same; they are looking for a different thing.
One is looking for a particular disease, P.G.S is easier, If a patient has had a particular disease and wants to make sure the baby does not have that disease, you screen the chromosome that contains that disease and look out for it but you have not said that embryo can become a baby because you have not looked at the other chromosomes to make sure there is no translocation or no mistake anywhere, so by the time you now look at them well, you can tell that not only are these embryos disease-free but can also become babies.
So that is the screening which is more difficult because we are looking out for everything. That is what we call PGS (Pre-implantation Genetic Screening), while P.G.D is looking for a particular disease, that is diagnosis. If you do PGD and PGS the chances that the woman will get pregnant is high, the factors we will now have to contend with are the factors the uterus contributes, not the factors that the embryo contributes to.
What are the benefits in this?
We can tell about compatibility in two people, for example, in genetics we use to say that one disease dominates while one is recessive. Two people who have recessive genes might not know but now we can find out if one has a recessive gene for a particular disease and if the person you want to marry also have a recessive gene, before you even get married. We can tell you either do not marry or if you are going to get married you need to do PGD.
What PGD is avoiding, touching of the foetus, hence the embryo is looked at before you even transfer and if it carries the disease don’t transfer there is no need for pregnancy. This is taking care of terminating pregnancies. Before we got to pre-implantation diagnosis, we used to have pre-natal diagnosis, the baby is already formed and you have a particular disease, sickle cell, for example two AS people married, and want to find out the status of the unborn baby. That is obtainable at the Lagos University Teaching Hospital (LUTH), Idi araba.
Pre-natal diagnosis is different, the baby is already there, you now take a sample from the baby – this could be either from the placenta or from the amniotic fluid then you make the diagnosis, to see whether the baby has that disease. If the baby has the problem now that you have a pregnancy already on going, you have to terminate that pregnancy. We can also test the sperm because there some men whose sperm would only give rise to bad embryos, usually older men because what makes an embryo not to become a baby is what we call Aneuploidy.
Aneuploidy can be detected in the sperm as well as the egg. Aneuploidy means there is an error in one of the chromosomal fluids, whether there is a delusion or a micro delusion or there is an addition, or something is wrong in the chromosomal arrangement, we can also see that in sperm, so this technology has helped us a to do a lot of things with IVF, in fact we can use it for Endoneutron, to see whether the Endoneutron is at the phrase at which implantation is possible or not, don’t forget I said 20 to 40 per cent of failures in IVF comes from the Endoneutron.
How popular is sex selection in your sector?
It is possible for us to select the particular sex of the baby, it is not illegal and babies from this process are normal and the procedure does not distort the quality of the babies as well.
The genetics is in short supply in the country. IVF is rather new and many people still don’t understand in Nigeria about the genetics and IVF because there are a lot of things that genetics has opened us all into that is not only sex selection. For example, diagnosing congenital abnormalities in babies without even taking samples from them; by taking samples from their mothers, we can know if you have abortion and the cause of the abortion from the tissue, because we can analyse the genes of the fetus.