IVF Sex Selection: How Does it Work?

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IVF sex selection, often incorrectly referred to as "gender selection," is a process where embryos are selected by their sex chromosomes during an IVF cycle in order to produce a male or female offspring, according to the wishes of the parents. Typically clinics will only offer sex selection for medical reasons linked to x chromosome disorders.

PGD Sex Selection

The primary method for sex selection is through a procedure called pre-implantation genetic diagnosis (PGD). As part of an IVF cycle, many embryos will be created and then typically the best quality embryo will be selected for implantation into the woman's uterus. PGD is performed before implantation to check for genetic defects, but the same process can identify the sex of the embryos. An embryo of the desired sex is then selectively implanted into the woman's uterus.

Microsorting

In another kind of sex selection procedure, called "microsorting," the  selection is done before embryos are created. Harvested sperm are separated one by one through a laser flow cytometer where analysis of their chromosomes into X-bearing (for female offspring) and Y-bearing (for male offspring) groups can be determined. The sperm which will produce the desired sex are then used to fertilize the eggs. A benefit for microsorting is that the sorted sperm can be used in less expensive procedures like IUI, in addition to IVF. This technology was developed by The Genetics and IVF Institute in Fairfax, Virginia.¹

When is Sex Selection Used?

PGD sex selection is uncommon and typically used for medical reasons, specifically, when couples know they are carriers for genetic conditions linked to biological sex. These X chromosome linked disorders are primarily found in males.

Outside of medical reasons, use of sex selection can be controversial. For this reason, different clinics will have their own policies towards implementing sex selection techniques. For example, some may only offer it for medical reasons, while other clinics may offer sex selection techniques if a patient already requires IVF for a fertility linked medical reason. It is rare to see a clinic offering IVF sex selection completely on its own without a linked reason.²

Another reason sex selection may be used is for family balancing.  Microsorting promotes itself as an option for family balancing. To qualify for family balancing associated sex selection  a couple must already have a child, and "sort for the underrepresented gender in the family."

Even without any ethical concerns, cost and effort are huge barriers to couples wishing to perform sex selection without a medical concern. IVF on its own is a daunting cost and picking an embryo to use based on sex could mean you are not picking the best quality embryo, which ultimately reduces your chances of a successful pregnancy.

Sex Selection Cost

The cost of sex selection varies from clinic to clinic. Typically, it may be $3,000 - $5,000 depending on whether microsorting or PGD sex selection is used. It is important to remember this cost will be in addition to the cost of any assisted reproductive fertility treatment procedure. Microsorting averages around $3,000 and could be used with an IUI cycle, which typically costs around $1,000 dollars. PGD sex selection averages around $5,000 and can only be conducted during an IVF cycle, which can cost about $12,000.

Sex Selection Success Rates

The success rates of the two procedures varies. In one recent study, the success rate for 218 couples using sex selection via PGD was 100% in terms of correctly achieving the desired sex. In general, PGD success rates are around 99%. PGD has such a high success rate because the sex of the embryo is already determined after fertilization and can accurately be verified. Unless there is an error in the lab, PGD sex selection should almost always pick the desired sex. However, although most studies on PGD  sex selection have a high success rate, there are studies that report a slightly lower successful pregnancy rate than IVF without PGD sex selection.³

The Genetics and IVF institute in Fairfax which licenses the Microsort technology claims a 93% success rate for females and an 82% success rate for males.

 

Sources:

¹https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3455094/

²http://www.asrm.org/globalassets/asrm/asrm-content/news-and-publications/ethics-committee-opinions/use_of_reproductive_technology_for_sex_selection_for_nonmedical_reasons-pdfmembers.pdf

³http://file.scirp.org/pdf/OJOG20120300024_52651345.pdf