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What is PGS/PGD and Who Should Get It Done?

It’s a pretty safe bet that in every aspect of life, the thing people desire the most is certainty. Sure, there are exceptions to this rule, but more often than not people want to know that they’re making a safe decision or that there will be a positive outcome to the action they are taking. That’s pretty abstract, so let’s talk about certainty in regards to starting a family. Every parent to be wants as much certainty as possible that their future child will be as healthy as possible with no foreseeable complications. While no one is born perfectly healthy with no genetic risk factors for conditions later in life, parents want to know what they can expect.

Every couple can relate to this, though it’s perhaps even more true of parents who are experiencing fertility issues and are considering trying in vitro fertilization in order to conceive. In vitro fertilization is the most commonly used procedure in order to circumvent fertility issues. While the 30-40% success rate is on par with the chances of getting pregnant naturally during any given cycle, there is still that additional element of uncertainty. After all this, will the baby be healthy? Will special care be required?

These questions can be anxiety inducing. That’s why many couples that are considering trying IVF in order to conceive opt for preimplantation genetic screening (PGS) and preimplantation genetic diagnosis (PGD). They are similar in concept to a prenatal diagnosis. These tests can tell you many things about the embryo created via IVF prior to embryo transfer. Here is what you can learn from PGS and PGD.

What is PGS?

PGS is a laboratory technique that allows for chromosomal analysis of the embryo before it is transferred to the womb to carry out the pregnancy. Chromosomes can tell a lot about the viability of the pregnancy. If the number of chromosomes differs from the usual 46, aneuploidy occurs. One way aneuploidy can manifest is in a child born with Down’s syndrome due to the extra chromosome. Aneuploidy can also result in a miscarriage, which is a significant risk factor for older women. By undergoing a PGS before embryo implantation, it can be determined if there is a chromosomal abnormality. If that is the case, the embryo won’t be transferred and a new fertility treatment course can begin without delay. If a miscarriage occurs, not only is this emotionally devastating, but it can also be a significant setback for starting a new fertility treatment. Generally, it takes several months following a miscarriage to be able to try fertility treatments again.

How does PGD differ?

PGD is a deeper analysis that goes beyond chromosomes to provide a genetic analysis before an embryo is transferred. PGD can test for autosomal recessive disorders and autosomal dominant disorders. Recessive disorders, like cystic fibrosis, don’t manifest in the parent, but they carry the genes for the disease. Dominant disorders, like Huntington’s Chorea, typically afflict one of the parents, which makes passing on the disorder even more likely than in the recessive scenario. Sex-linked disorders attached to the X or Y chromosome can also be identified. Essentially, PGD works to identify embryos that are at high risk for inheriting a disorder and identifying embryos that are unaffected.

Who should opt for PGS and PGD?

Anyone is a good candidate, but if you or your partner have any genetic risk factors that you are aware of, testing is strongly recommended. Even if the two of you don’t necessarily have any conditions that you’re aware of, someone in your family may. For example, having a close relative with Down’s syndrome or cystic fibrosis can increase the chances of you genetically passing that on to your child.

Additionally, PGS may be recommended for reasons beyond checking for genetic conditions in the embryo. If you’ve already suffered multiple miscarriages, PGS may be able to shed light on the reasons why and to decrease the chances of it occurring again. PGS can also address issues relating to infertility.


While absolute certainty is hard to come by, gathering enough facts and risk factors can give you the insight you desire regarding your baby. While many different genetic conditions can be identified with PGS/PGD, you can also find out if the embryo being tested is viable for a successful pregnancy. If you already know that you or your partner have risk factors that may be passed onto your child, it’s recommended that you opt for this testing. If you have any questions about fertility services or testing, or you’re ready to get the process started, book an appointment online to schedule a consultation today. Dr. Mor and the team at California Center for Reproductive Health are here to provide the care and fertility services needed so you can start the happy, healthy family you’ve always wanted.