PGT-A testing accuracy for sex determination: A complete guide for IVF patients

If you're going through IVF, finding out your embryo’s sex can carry deep emotional weight. Maybe it’s part of building the family you’ve always imagined or a way to reduce the risk of passing on a genetic condition. 

During the IVF process, you might be offered a test called Preimplantation Genetic Testing for Aneuploidy (PGT-A). Its main goal is to screen embryos for chromosomal abnormalities before transfer. Along with those results, it can also reveal the biological sex of each embryo.

In this article, we’ll walk you through how sex is identified during PGT-A, explore PGT-A testing accuracy for sex determination, and explain the factors that can sometimes lead to confusion or error. We’ll also look at the ethical questions that arise when using this information to guide embryo selection. 

Note: While many people search for “PGT-A testing gender accuracy” when trying to understand how embryos are assessed during IVF, PGT-A actually reveals an embryo’s biological sex, not gender identity. For that reason, we’ll use the term “sex” throughout this article to talk about the clinical accuracy of what PGT-A determines.

What is PGT-A, and how does it reveal sex?

PGT-A is a screening tool used during IVF to assess whether an embryo has the correct number of chromosomes. It helps identify embryos with extra or missing chromosomes (aneuploidies), which are a common cause of implantation failure, miscarriage, or genetic conditions like Down syndrome or Turner syndrome. 

PGT-A can support more confident decisions during embryo selection and increase the chances of a successful, healthy pregnancy. The process begins around day five or six of embryo development when the embryo forms a blastocyst with two distinct cell groups: 

1. The inner cell mass, which becomes the fetus

2. The trophectoderm, which develops into the placenta

An embryologist carefully removes 5–10 cells from the trophectoderm, a technique that reduces potential harm to the embryo while providing enough DNA for testing. The cells are then sent to a genetics lab, while the embryo is frozen and stored at the clinic.

Source: Sbtlneet

Although the main goal of PGT-A is to screen for chromosomal health, it also provides information about each embryo’s biological sex because the test examines all 24 chromosome types: 

1. The 22 autosomal pairs — Chromosomes that determine characteristics like eye color and height.

2. The two sex chromosomes (X and Y) — Embryos with two X chromosomes are genetically female (XX), and those with one X and one Y are genetically male (XY).

Bonus read — Dive deeper into IVF and embryo testing by reading our other detailed guides:

• How long does PGT-A testing take?

• What is PGS?

• What is PGT-P?

• What is PGT-SR?

PGT-A testing and sex accuracy: How reliable is it?

If the test is performed under optimal laboratory conditions, PGT-A can determine whether an embryo is chromosomally male or female with more than 98% accuracy. Some studies have even found that sex selection with PGT-A is 100% accurate, provided that you become pregnant with IVF.

However, like all medical testing, PGT-A is not completely infallible. Some factors that can affect PGT-A testing sex accuracy include:

• Mosaicism: Occurs when two or more groups of cells possess a different genetic makeup. For example, a biopsy of aneuploid cells in a mosaic embryo could incorrectly label a male embryo as female if the Y chromosome is absent in sampled cells.

• Lab errors: Sample mix-ups, technical limitations, or labeling mistakes.

• Embryo quality: Poor biopsy samples or degraded DNA.

Even with a high degree of accuracy, occasional mismatches between PGT-A sex results and later ultrasounds occur and can be confusing, especially for hopeful parents looking for reassurance. But in most cases, these discrepancies turn out to be benign, often stemming from limitations of early imaging. 

While it’s natural to have questions, mismatches rarely indicate serious problems and are typically resolved with time, additional scans, or follow-up testing. 

One IVF patient shared their experience on Reddit after their 20-week ultrasound:

[Reddit](https://www.reddit.com/r/IVF/comments/1gjqcgt/pgta_reports_wrong_gender/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button)(330)

Medical reasons for sex selection

While most conversations around sex selection focus on non-medical reasons, there are cases where knowing an embryo’s sex can have important health implications. This is especially true when there’s a risk of passing on a sex-specific genetic condition. 

In such cases, Preimplantation Genetic Testing for Monogenic Conditions (PGT-M) may be recommended alongside PGT-A. Unlike PGT-A, which screens for overall chromosomal health, PGT-M looks for a specific inherited disorder known to run in the family. Fertility clinics often perform PGT-M and PGT-A at the same time to ensure the healthiest possible embryo is selected.

PGT-M can discover genetic mutations tied to the sex chromosomes, which can be:

1. X-linked conditions: These are genetic disorders passed from the mother (carrier) to the child. Female carriers of X-linked recessive conditions have a 50% chance of passing the mutation to each son, who may be affected if their mother inherits it. Males can’t pass X-linked conditions to their sons, but they will always pass the affected X chromosome to their daughters, making them carriers.

2. Y-linked conditions: These are genetic disorders passed from the father only to genetically male children, never to females. All sons inherit the Y chromosome and its mutations, while daughters are unaffected and cannot pass the mutation to their offspring.

Source: RDNE Stock project

Sex-linked conditions to consider in embryo selection

For families with sex-specific genetic conditions, knowing an embryo’s sex can help reduce the risk of passing on serious disorders and offer peace of mind. Below is an overview of conditions that may influence decisions about embryo transfer:

Screening for aneuploidy and learning the embryo’s sex through PGT-A can be a medically significant step. However, PGT-A doesn’t reveal whether an embryo carries specific X- or Y-linked disorders.

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PGT-A testing and sex selection

As more IVF cycles include PGT-A, many parents have access to information about their embryos’ sex.

Source: Vlada Karpovich

Personal family-building decisions can be rooted in:

• Family balancing: If you have children of one sex, you may wish to experience raising the other.

• Emotional healing: Past pregnancy loss or trauma might shape your preferences.

• Personal preference: You may dream of parenting a boy and a girl or feel that your family will only be complete with a child of a certain sex.

• Having a single child: If you plan to have only one child, this choice can hold real emotional weight, so you may feel strongly about having input into the sex of that child.

It’s important to recognize that the motivations behind sex selection are often deeply personal and complex.

[Reddit](https://www.reddit.com/r/IVF/comments/1jbh7pk/comment/mhu2b31/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button)(265)

Source: MART PRODUCTION

Limitations of PGT-A testing

PGT-A can provide valuable information about an embryo’s chromosomal health, helping identify those most likely to implant and develop fully, but it’s not without limitations. 

PGT-A only looks for large-scale chromosomal abnormalities, such as missing or extra chromosomes. Combined with PGT-M, it can help avoid some inherited single-gene conditions, including sex-specific ones. 

Still, it can’t detect future risks for chronic or late-onset diseases, like Alzheimer’s disease or breast cancer. That’s why you need to consider PGT-P testing, which helps define embryos based on their long-term potential health outcomes.

PGT-P  can pinpoint the likelihood of heart conditions, diabetes, cancer, and more. It can also help predict your future child’s mental health, hair color, eye color, height, and more. or athletic ability that other testing formats don’t offer.

The best way to understand PGT-P results is to use advanced genetic optimization tools to add clarity to your process. For parents who want to understand inherited health risks better or learn more about their embryos beyond chromosomal status, Nucleus Embryo is an excellent next step.

Nucleus Embryo: The next step in your IVF journey

PGT-A and PGT-M provide valuable information and can improve implantation success, but it’s PGT-P that gives you data on the more complex health risks for embryos. If you’ve already had PGT-P testing, sign up for Nucleus Embryo for more decision-assisting analyses.

Nucleus Embryo is a genetic optimization platform that uses PGT-P or whole-genome embryo data to extract granular insights about the embryos’ potential health, traits, and other factors that affect their well-being.

You get an interactive dashboard to sort, compare, and filter your embryos based on factors that matter to you. If you have multiple healthy embryos, you can use Nucleus Embryo insights to have more agency over your decision. Gain insights into aspects that matter to you, including:

• Advanced analyses for late-onset and chronic conditions, like cancer, Alzheimer’s disease, and heart disease that can impact your future child’s health

• Risk of developing neurological and mental health conditions like anxiety, bipolar disorder, depression, and insomnia

• Traits like eye and hair color, height, the likelihood of being left-handed, etc.

The platform presents your embryos side by side, clearly displaying genetic traits and health risks in an easy-to-understand format. If needed, you can access genetic counseling via Nucleus.

Nucleus also offers multigenerational DNA analysis at any point in your fertility journey. You and your partner can gain more detailed insights into your family’s health with Nucleus Family, which screens for over 2,000 conditions alongside chronic diseases like Alzheimer’s disease, heart disease, type 2 diabetes, and more. 

Getting started with Nucleus Embryo

Once you’ve completed PGT-P or other testing and have your results ready, it’s easy to get started with Nucleus Embryo:

1. Ask your clinic for PGT-P testing with LifeView by Genomic Prediction

2. Sign up for Nucleus Embryo during or after you complete your IVF cycle

3. Request your embryos’ PGT-P DNA data from your clinic

4. Upload the data to Nucleus Embryo and analyze the embryo analysis report

While the decisions about which embryos to transfer remain yours, Nucleus Embryo makes the process easier and more informed.

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Here are some more helpful resources to support you as you make decisions about your family’s future:

Featured image source: RDNE Stock project