PGD vs. PGS in IVF: What You Need to Know
In-vitro fertilization (IVF) is a revolutionary technique that has helped countless couples fulfill their dream of becoming parents. However, not every IVF cycle results in a successful pregnancy, especially when genetic or chromosomal abnormalities are involved. This is where advanced genetic screening methods like PGD and PGS come into play. These techniques allow doctors to examine embryos before implantation, ensuring that only healthy ones are transferred into the uterus. PGD helps detect specific inherited diseases, while PGS checks for chromosomal abnormalities that could cause miscarriage or failed implantation. By identifying potential issues early, these tests improve IVF success rates, reduce the risk of genetic disorders, and offer couples greater confidence in their fertility journey. In this article, we will explore what PGD and PGS are, how they work, who can benefit from them, and why they are becoming essential tools in modern IVF treatments. Why should you trust SELECT IVF for INDIA? What is PGD (Preimplantation Genetic Diagnosis)? PGD is a technique used during IVF to test embryos for specific genetic diseases or disorders inherited from parents. It helps detect single-gene mutations, like cystic fibrosis or thalassemia, before embryo transfer. In PGD, a few cells are taken from an embryo on day 5 or 6 of development (blastocyst stage). These cells are analyzed for known genetic conditions. Only embryos without those specific diseases are selected for implantation. PGD is most useful for couples with a known family history of genetic disorders and helps prevent the transmission of life-threatening conditions to the child. What is PGS (Preimplantation Genetic Screening)? PGS, now commonly called PGT-A (Preimplantation Genetic Testing for Aneuploidy), checks embryos for chromosomal abnormalities. It ensures the right number of chromosomes are present, reducing the risk of miscarriage or failed implantation. Unlike PGD, PGS doesn’t test for specific diseases. Instead, it looks at whether the embryo has a normal chromosomal number (euploid) or an abnormal number (aneuploid). This is especially helpful for older women, as age increases the chance of chromosomal issues like Down syndrome. PGS helps select the healthiest embryos for transfer, increasing IVF success and reducing pregnancy risks. Difference Between PGD and PGS While both PGD (Preimplantation Genetic Diagnosis) and PGS (Preimplantation Genetic Screening, now referred to as PGT-A) are genetic tests performed during the IVF process, they serve very different purposes and are recommended for different reasons. The most important difference lies in what each test looks for and who it is meant for. PGD is used to identify specific genetic mutations that may be passed from parents to their children. These mutations can cause serious, often life-threatening conditions such as cystic fibrosis, Tay-Sachs disease, muscular dystrophy, thalassemia, or sickle cell anemia. PGD is typically recommended for couples who are known carriers of a genetic disorder or who already have a child affected by such a disease. Through PGD, embryos that carry these defective genes can be avoided during transfer, significantly reducing the risk of the child inheriting a genetic condition. PGS, on the other hand, is not focused on specific diseases but instead checks the overall chromosomal health of embryos. It ensures that each embryo has the correct number of chromosomes 46 in total, arranged in 23 pairs. Embryos with too few or too many chromosomes (aneuploidy) often result in failed implantation, miscarriage, or conditions such as Down syndrome. PGS is especially beneficial for women over 35, couples with a history of recurrent miscarriage, or those who have experienced repeated IVF failures. In simple terms: Both PGD and PGS require embryos to be created through IVF, as the testing is done on embryos outside the body. Depending on a couple’s fertility history and genetic background, doctors may recommend either test or both to help increase the chances of a healthy, successful pregnancy. How Are PGD and PGS Performed? Both procedures start with standard IVF. After egg retrieval and fertilization, embryos grow for about five days. At the blastocyst stage, a few cells are gently removed from each embryo. These cells are sent for genetic analysis. Advanced lab techniques like Next-Generation Sequencing (NGS) or array-CGH (Comparative Genomic Hybridization) are used to detect abnormalities. Once results are ready (usually within a few days), only healthy embryos are chosen for implantation. The remaining embryos may be frozen for future use. This entire process is done under highly controlled conditions by embryologists and genetic specialists to ensure accuracy. Benefits of PGD and PGS in IVF 1. Improved IVF Success Rates By selecting genetically normal embryos, PGS improves the chances of successful implantation and pregnancy. It reduces the number of IVF cycles needed, saving time, emotional energy, and costs in the long run. 2. Lower Risk of Miscarriage Many miscarriages result from chromosomal abnormalities. By transferring only normal embryos, PGS can significantly reduce the chances of miscarriage. 3. Avoidance of Genetic Disorders PGD ensures that embryos carrying severe inherited disorders are not transferred, allowing couples to avoid passing on diseases like Tay-Sachs, thalassemia, or Huntington’s. 4. Healthier Babies The ultimate goal of PGD/PGS is to increase the likelihood of a healthy baby. Selecting embryos with the right genetic makeup reduces health risks during pregnancy and after birth. Who Should Consider PGD and PGS Testing? These tests are particularly recommended in the following cases: While PGD and PGS aren’t required for every IVF cycle, they provide peace of mind and may improve the outcome for many patients with specific risks. Are PGD and PGS Safe? Yes, both tests are considered safe and do not harm the embryo when performed correctly by skilled embryologists. The cell biopsy is done carefully without affecting embryo development. However, like any medical procedure, there is a small risk of damage during cell extraction or errors in analysis. Modern IVF labs follow strict safety protocols. Embryos are monitored closely, and only viable ones are selected for transfer. Over the years, thousands of healthy babies have been born following PGD and PGS, proving their safety and effectiveness. Limitations and Ethical Considerations Despite their benefits, PGD and PGS have some limitations: Clinics…
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