Since the first successful In Vitro Fertilization (IVF) live birth in 1978, the technology behind infertility treatment has helped millions of couples and individuals grow their family who might otherwise not have had the chance. Beyond making conception possible for intended parents, advances in IVF technology allow us to take an even deeper look into the genetic health and viability of embryos created through fertility care.
Preimplantation Genetic Testing
A modern practice in IVF technology is the testing of embryos prior to implantation through a process called Preimplantation Genetic Testing (PGT). PGT is used to screen embryos for specific chromosomal and genetic disorders before they are transferred into the uterus to hopefully achieve a pregnancy.
After embryos are created they are grown in the IVF laboratory for five days. If choosing to utilize PGT, it’s at this point that the embryologist uses a laser to remove a small sample of cells from the future placenta of the embryo under a microscope. These cells are then tested for the presence of chromosomal abnormalities and, in certain cases, genetic disorders.
By collecting this information about each embryo’s genetic status, we can identify the embryos that are most likely to successfully implant and lead to a healthy pregnancy.
Sex Identification in PGT
As PGT looks at the chromosomal make-up of each embryo, the identification of the sex of each embryo is a byproduct of this process. Each embryo receives 22 chromosomes (1-22) and 1 sex chromosome from each parent, for a total of 23 pairs of chromosomes.
The female passes on only an X chromosome, while the male can pass on an X or a Y chromosome, thus determining the sex of the embryo. A pair of XX sex chromosomes indicates a female embryo while a pair of XY sex chromosomes indicate a male embryo.
Sex-Linked Genetic Diseases
In the past, “sexing” of the embryos was used by patients who carry X-linked genetic conditions, such as hemophilia or muscular dystrophy. Today, however, more precise techniques, such as PGT for “monogenic” conditions (PGT-M) are available to provide more precise information about the embryo’s genetic status. In addition to identifying the sex, PGT-M is able to determine which embryos are unaffected versus affected males and which are carrier versus non-carrier females.
Although the sex of the embryo may be useful in determining the risk for a limited number of genetic conditions, most patients who have an inherited, X-linked condition appreciate having the opportunity to differentiate between these more precise categories of risk.
Sex Selection
When intended parents want to transfer an embryo of a specific sex, they can opt into sex selection as part of their IVF process. IVF can significantly improve the chance of having a child of a particular sex. By undergoing IVF with PGT-A, patients are able to learn the sex of the embryos, and (assuming embryos of the preferred sex are available), transfer the embryo of the desired sex.
Previously, technologies such as sperm sorting were available to enhance the chance of creating embryos with XY or XX chromosomes. However, this technique is not approved by the U.S FDA and is not available in the US.
Why Intended Parents Might Choose Sex Selection
Family Balancing
Family balancing is the term used when intended parents decide to transfer an embryo of a certain sex for the purpose of balancing the representation of both sexes in their family. When some families have one or multiple children of one sex, they may have a strong desire to balance their family and have a baby of a different sex.
Preventing Genetic Diseases
As mentioned before, parents concerned about passing on a sex-linked genetic disease might decide to transfer an embryo of a particular sex to protect their future child from this disease.
Before pursuing embryo testing to prevent the transmission of genetic disease, it is strongly recommended that parents meet with a genetic counselor. During this time you can discuss how the condition of concern is inherited, whether more specific testing of the embryos for the gene in question is possible, and by what degree transferring an embryo of each sex will reduce the risk for the condition.
Personal Reasons
There are a variety of other reasons why someone might choose sex-selection on their family building journey. Some reasons might include religious, cultural, medical, or other reasons that are unique to an individual. The path to parenthood is not linear, and each family’s journey is uniquely their own.
Risks of Sex Selection
If intended parents decide to pursue sex selection or family balancing, IVF and PGT will need to be utilized. PGT generates additional costs along with IVF but it generally does not expose the patient, or embryo, to any significant additional risks aside from those that come with IVF.
There are some small risks associated with embryo biopsy which are specific to the experience of the clinic and embryologists performing the biopsies. At ORM, we have biopsied well over 25,000 embryos and have found that <1% do not survive the biopsy. The long-term risks of the biopsy to the fetus and baby are also presumed to be low based on the information we have at this time.
PGT itself and learning the chromosomal status of the embryos from a health standpoint, aside from the sex may or may not increase the chance for a successful pregnancy compared to an IVF cycle without PGT. The sex and health of the embryos created is not a guarantee. At ORM Fertility, our goal is to help you achieve a successful, healthy pregnancy that aligns with your unique family building journey.*
Limitations of Sex Selection
Though this can be a great option for some growing families, it’s not always accessible. Sex selection and family balancing is legal in the United States, but this isn’t the case in some other countries. In addition to high success rates, access to sex-selection, and family balancing in the United States make it a highly popular location to seek IVF treatment.
Is Sex Selection or Family Balancing Right for My Family?
All things considered, the decision to transfer an embryo of a particular sex is unique and deeply personal to each individual. It is up to the intended parent to decide whether or not they want to know the sex of each embryo and proceed with transferring an embryo of their choice. Embryo sex information can be omitted from all reports at the request of the patient.
It’s important to remember there is never a guarantee that the embryos created will consist of both sexes or that an embryo of the desired sex will be healthy and chromosomally normal. Even with some uncertainty, this option for family building has been successful for many growing families.
We are here to support and guide each individual patient on their unique path to parenthood, always prioritizing our patients’ needs and the goal of a healthy family. We strive to provide a range of family building options and patient education so our patients can lead their care with the information they need to make better, informed decisions.
To learn more about sex-selection, family balancing, and PGT options, schedule a consultation with one of our fertility specialists today.
