Why Genetic Testing Is Important After the Age of 35?

What Every Woman Over 35 Needs to Know About Chromosomes, Embryo Testing, and Protecting Her Baby's Health

When a woman crosses the threshold of 35, something shifts in the conversation about fertility and pregnancy — and it centres around a single biological reality: chromosomes.

At 25, approximately 10 to 15 percent of a woman's eggs carry a chromosomal abnormality. By 35, that figure rises to 25 to 35 percent. By 40, it approaches 50 percent. By 45, 75 to 90 percent of eggs may be chromosomally abnormal. These are not statistics to frighten — they are clinical realities that explain why miscarriage rates rise with age, why certain chromosomal conditions are more common in babies born to older mothers, and why genetic testing becomes increasingly important from the mid-30s onward.

Understanding what genetic testing is, why it is recommended, what it can and cannot tell you, and what your options are if results are concerning is one of the most important pieces of knowledge any woman over 35 — or any couple undergoing IVF — can have. This blog is dedicated to giving you that knowledge clearly, honestly, and compassionately.

Genetic testing in fertility and pregnancy is not about fear. It is about information — information that allows you to make the most informed decisions about your embryos, your pregnancy, and ultimately your family, with the support of a clinical team that walks every step of that journey with you.

Why Do Chromosomal Errors Increase With Age?

To understand why genetic testing matters after 35, it helps to understand what is actually happening to eggs as a woman ages — at the level of chromosomes, cell division, and the biology that no amount of healthy living can fully reverse.

Eggs and the Meiotic Clock

A woman's eggs are not produced fresh throughout her life, the way sperm are in men. Instead, all the eggs a woman will ever have are formed before she is even born — during fetal development in the womb. By birth, these eggs are suspended in an incomplete state of cell division called meiotic arrest, where they will remain until each one is recruited for ovulation, potentially decades later.

This extended period of suspended division — which can last 40 or more years for eggs released in a woman's late 30s and early 40s — takes a biological toll. The proteins that form the spindle apparatus, the cellular machinery responsible for correctly separating chromosomes during the final stages of meiosis, deteriorate over time. When an egg finally completes its division at ovulation, the ageing spindle is more likely to make errors — allowing chromosomes to be pulled to the wrong side, resulting in an egg with too many or too few chromosomes.

This chromosomal error is called aneuploidy. An aneuploid egg, when fertilised, produces an aneuploid embryo. And an aneuploid embryo almost invariably fails to implant, miscarries early, or in a smaller proportion of cases develops into a pregnancy with a chromosomal condition.

The Most Common Chromosomal Conditions

The chromosomal conditions most commonly associated with advanced maternal age arise from errors in the separation of specific chromosomes during egg maturation. Trisomy 21 (Down syndrome) involves an extra copy of chromosome 21 and is the most common chromosomal condition compatible with survival. Trisomy 18 (Edwards syndrome) and Trisomy 13 (Patau syndrome) involve extra copies of chromosomes 18 and 13 respectively, both associated with severe developmental abnormalities where most affected pregnancies end in miscarriage or early neonatal death. Monosomy X (Turner syndrome) involves a single X chromosome rather than the normal two, and is more likely to occur in spontaneous miscarriage than in live birth. Extra or missing copies of almost any other chromosome can also occur, and most are incompatible with development beyond the early embryo or fetal stages.

Why 35 Is the Clinical Threshold — Not an Arbitrary Line

The age of 35 is widely cited as the point at which genetic testing recommendations intensify — but why 35 specifically? Before 35, the background risk of chromosomal conditions in a pregnancy is low enough that the risks of invasive testing were historically considered to outweigh the benefits for most women.

By 35, the risk of a Down syndrome pregnancy reaches approximately 1 in 270. By 40, the risk is approximately 1 in 100. By 45, it approaches 1 in 25. These are population-level figures — individual risk is modified by other factors including partner age and family history — but they illustrate why the recommendation landscape changes meaningfully in the mid-30s.

Importantly, modern genetic screening — particularly non-invasive prenatal testing (NIPT) — has radically changed this risk-benefit calculation. NIPT is performed on a maternal blood sample and carries no procedural risk to the pregnancy, making earlier and broader screening both safer and more accessible.

What Genetic Testing Is Available and When Is It Used?

Genetic testing in the context of fertility and pregnancy spans two distinct moments: before pregnancy, through testing of embryos in the IVF laboratory (preimplantation genetic testing), and during pregnancy, through prenatal screening and diagnostic tests. Each has a different purpose, different timing, and different implications.

The main tests available are PGT-A (Preimplantation Genetic Testing for Aneuploidies), which screens embryos for abnormal chromosome number before transfer; PGT-M (Preimplantation Genetic Testing for Monogenic Disorders), which screens embryos for specific single-gene inherited disorders such as thalassaemia or spinal muscular atrophy; PGT-SR (Preimplantation Genetic Testing for Structural Rearrangements), which screens embryos where a parent carries a chromosomal rearrangement; NIPT (Non-Invasive Prenatal Testing), which screens maternal blood during pregnancy for fetal chromosomal conditions; CVS (Chorionic Villus Sampling), an invasive diagnostic test sampling placental tissue at 11–13 weeks; and Amniocentesis, an invasive diagnostic test sampling amniotic fluid at 15–20 weeks.

PGT-A: Choosing the Right Embryo Before the Transfer

Preimplantation Genetic Testing for Aneuploidies — PGT-A — is the most directly relevant genetic testing tool for women undergoing IVF after the age of 35. It analyses the chromosomal status of each IVF embryo before transfer, identifying which embryos are chromosomally normal (euploid) and which carry numerical chromosomal errors (aneuploid).

The goal is not to eliminate or discard embryos arbitrarily. It is to identify, from the cohort of embryos produced in a cycle, which one or two have the highest genuine chance of implanting, developing into a healthy pregnancy, and resulting in a live birth. In a 38-year-old woman whose IVF cycle produces five blastocysts, one or two of those embryos may be chromosomally normal and three or four may not be. Without PGT-A, the embryo selected for transfer is chosen on morphology alone — its appearance — with no information about its chromosomal status. With PGT-A, the euploid embryo is transferred first.

How PGT-A Works: From Embryo to Result

PGT-A begins in the embryology laboratory on day 5 or 6 of embryo culture, when the embryo has developed to the blastocyst stage. At this point, the embryologist performs a trophectoderm biopsy — a procedure in which 5 to 8 cells are carefully removed from the outer cell layer of the blastocyst using a fine laser-guided needle. The inner cell mass, which will form the baby, is not touched.

The embryo is then immediately vitrified while the biopsied cells are sent to a specialist genetics laboratory. The cells undergo whole-genome amplification followed by next-generation sequencing (NGS), which allows analysis of all 23 pairs of chromosomes simultaneously. Results are typically available within 7 to 14 days. Embryos confirmed as euploid are then available for transfer in a subsequent frozen embryo transfer cycle, at the optimal time for the individual patient's uterine receptivity.

What PGT-A Can and Cannot Tell You

PGT-A can reliably detect gains or losses of whole chromosomes — trisomies, monosomies, and polyploidy — across all 23 chromosome pairs. This covers the vast majority of chromosomal abnormalities that cause IVF failure, miscarriage, and conditions such as Down syndrome.

PGT-A cannot detect single-gene disorders (which require PGT-M), very small chromosomal deletions or duplications depending on the resolution of the platform used, mosaicism in some cases where only a proportion of cells carry the abnormality, or abnormalities in the inner cell mass that are not reflected in the trophectoderm cells biopsied.

A PGT-A result of euploid does not guarantee pregnancy — the uterine environment and transfer quality also matter. But it does substantially increase the per-transfer probability of success and significantly reduce the probability of miscarriage compared to untested embryo transfer in women over 35.

Who Benefits Most from PGT-A?

PGT-A is most beneficial for women aged 35 and over undergoing IVF, women with a history of recurrent implantation failure despite good-quality embryos, women with recurrent miscarriage, women with a previous pregnancy affected by a chromosomal condition, women with severely diminished ovarian reserve where each cycle produces few embryos, and couples where a chromosomal rearrangement has been identified in one partner.

At Urvara, trophectoderm biopsies are performed by senior embryologists trained to the highest standards, and our genetic analysis is conducted in partnership with accredited genetics laboratories using next-generation sequencing platforms. Every patient considering PGT-A receives a dedicated pre-test counselling session to understand what the test offers, what it cannot detect, and how results will be used in their treatment planning.

PGT-M: Preventing Inherited Genetic Conditions From Passing to Your Child

While PGT-A screens for chromosomal number errors, PGT-M screens for specific single-gene inherited conditions that run in families. This testing is not age-related in the same way as PGT-A. It is relevant at any age for couples who carry a known genetic condition and want to ensure it is not passed to their child.

Which Conditions Can PGT-M Screen For?

PGT-M can screen embryos for virtually any single-gene disorder for which the causative mutation has been identified. Common conditions for which couples in India seek PGT-M include beta-thalassaemia, sickle cell disease, Spinal Muscular Atrophy (SMA), cystic fibrosis, Duchenne Muscular Dystrophy, BRCA1 and BRCA2 mutations associated with hereditary breast and ovarian cancer, Huntington's disease, and many other single-gene disorders as gene identification and testing protocols continue to expand.

How PGT-M Is Different from PGT-A

PGT-M requires a period of preparatory laboratory work — typically 3 to 6 months — before an IVF cycle can begin. This is because a bespoke genetic testing probe must be developed for each couple's specific mutation or combination of mutations. The probe design process involves analysis of DNA from the affected individual or carrier, the couple themselves, and sometimes family members, to create a testing strategy that is specific and reliable for that family's unique genetic situation.

At Urvara, we coordinate the PGT-M preparation process alongside your IVF readiness assessment, so that by the time your stimulation cycle begins, the genetic testing platform is ready and validated. For couples with a known inherited genetic condition who are seeking IVF, PGT-M represents one of the most profound applications of reproductive medicine — the ability to give your child a life free of a condition that has affected your family.

NIPT: The Safest Prenatal Screening Available

Non-Invasive Prenatal Testing — NIPT — has transformed prenatal care for women over 35 since it became clinically available. It offers high accuracy for the most common chromosomal conditions from as early as 10 weeks of pregnancy, with no risk to the baby whatsoever.

How NIPT Works

During pregnancy, small fragments of cell-free fetal DNA circulate in the mother's bloodstream, released from placental cells. NIPT analyses a maternal blood sample to identify and sequence these fetal DNA fragments, comparing the proportions of DNA from each chromosome to identify gains or losses that would indicate a chromosomal abnormality in the fetus.

NIPT is a screening test — it provides a risk estimate, not a definitive diagnosis. A high-risk NIPT result indicates that further testing is warranted to confirm. A low-risk result substantially reduces the probability of the screened conditions but does not eliminate it entirely.

What NIPT Screens For

Standard NIPT panels screen for Trisomy 21 (Down syndrome) with a detection rate of approximately 99 percent and a false positive rate below 0.1 percent, Trisomy 18 (Edwards syndrome) with a detection rate of approximately 97 to 99 percent, Trisomy 13 (Patau syndrome) with a detection rate of approximately 92 to 99 percent, and sex chromosome conditions including Turner syndrome and Klinefelter syndrome. Extended panels also screen for selected microdeletion syndromes such as DiGeorge syndrome.

NIPT vs. Traditional First Trimester Screening

Traditional first trimester screening combines a nuchal translucency ultrasound scan with blood tests measuring pregnancy hormones to generate a combined risk estimate. This combined screening has detection rates of approximately 85 to 90 percent for Down syndrome at a 5 percent false positive rate.

NIPT achieves detection rates above 99 percent for Down syndrome at a false positive rate below 0.1 percent — significantly outperforming traditional screening. This means fewer unnecessary invasive tests, less anxiety from false positive results, and more confident reassurance when results are low risk. For women over 35, NIPT is now the preferred first-line prenatal screening approach at Urvara.

CVS and Amniocentesis: When Definitive Answers Are Needed

NIPT is a screening test — it tells you the probability of a chromosomal condition, not whether it is definitively present. When NIPT returns a high-risk result, when other aspects of screening are abnormal, or when a couple carries a known genetic condition that requires diagnostic confirmation, invasive prenatal diagnostic testing provides definitive answers.

Chorionic Villus Sampling (CVS)

CVS is performed between 11 and 13 weeks of pregnancy. A thin needle is guided by ultrasound through the mother's abdomen to the placenta, where a small sample of chorionic villi — placental tissue — is removed. Because the placenta and the fetus share the same genetic origin, analysis of placental cells provides a comprehensive picture of the fetal chromosomal and genetic status. The advantage of CVS is its timing — it can be performed in the first trimester, allowing couples to receive diagnostic information earlier in the pregnancy. Results from chromosomal analysis are typically available within 10 to 14 days, with faster preliminary results available within 2 to 3 days.

Amniocentesis

Amniocentesis is performed between 15 and 20 weeks of pregnancy. A needle is guided by ultrasound through the abdomen into the amniotic sac, and a small sample of amniotic fluid is withdrawn. This fluid contains fetal cells that are cultured and analysed for chromosomal and specific genetic conditions. Amniocentesis carries a slightly lower procedural miscarriage risk than CVS and is the gold standard for prenatal diagnosis when a comprehensive genetic analysis is required.

At Urvara Fertility Centre, we never recommend an invasive prenatal diagnostic test without a dedicated pre-test counselling session in which the indication, the procedure, the risks, and the implications of possible results are discussed in full. The decision to proceed with CVS or amniocentesis is always the couple's own informed decision — made with our support and guidance, but never under pressure.

What Genetic Testing Results Mean — and How to Navigate Them

When Results Are Reassuring

For the majority of patients, genetic testing returns reassuring results. A PGT-A panel that identifies one or two euploid embryos from a cohort provides a clear path forward — a transfer with the highest possible per-attempt success rate. An NIPT result returned as low risk is a significant source of reassurance for a pregnant woman over 35 who has spent weeks anxious about chromosomal conditions.

When Results Are Unexpected

Sometimes results carry unexpected news. A PGT-A result showing that all embryos from a cycle are aneuploid is devastating — it means no embryos from that cycle can be transferred, and a new cycle will be needed, or alternative options must be considered. An NIPT result flagged as high risk for Down syndrome brings a cascade of emotions, questions, and decisions.

At Urvara, unexpected results are never delivered in a brief clinic corridor conversation. They are discussed in a private, dedicated consultation with one of our senior clinicians, with time to absorb the information, to ask every question, and to understand every option. Our counselling team is available in the same conversation or immediately after, because clinical information and emotional support must go hand in hand.

What a Positive Result Does and Does Not Mean

A high-risk screening result — whether from NIPT or first trimester combined screening — is not a diagnosis. It is a signal that further investigation is warranted. Many women who receive a high-risk NIPT result and proceed to amniocentesis receive a normal diagnostic result.

An aneuploid result on a single PGT-A cycle does not mean that all future embryos will be aneuploid, or that a successful pregnancy is impossible. It provides information about that cycle's embryo cohort. The result is information. What happens next is a conversation.

Myths vs. Facts: Genetic Testing in IVF and Pregnancy

Myth: If I am healthy and have no family history of genetic conditions, I do not need genetic testing after 35.

The chromosomal errors that occur with increasing frequency after 35 are not inherited — they arise de novo from the ageing egg maturation process and cannot be predicted from family history. A completely healthy woman with no family history of any genetic condition faces the same age-related aneuploidy rate as any other woman her age. Age is the primary risk factor, and it affects everyone.

Myth: PGT-A damages embryos and reduces their chance of implanting.

When performed by trained embryologists using validated technique, trophectoderm biopsy does not significantly impair embryo viability. Randomised controlled trials comparing PGT-A embryo outcomes to untested embryo outcomes show that the biopsy procedure itself does not reduce implantation potential. Multiple large studies and live birth data from around the world confirm that PGT-A biopsied embryos achieve excellent outcomes when transferred.

Myth: NIPT can tell me for certain whether my baby has Down syndrome.

NIPT is a screening test, not a diagnostic test. A high-risk NIPT result means the probability of Down syndrome is elevated, and diagnostic confirmation through amniocentesis or CVS is recommended. It cannot by itself confirm a diagnosis. This distinction is clinically important and is always explained to our patients before NIPT is arranged.

Myth: If genetic testing shows an abnormality, there is nothing that can be done.

Genetic testing provides options — it does not eliminate them. A PGT-A result showing all embryos are aneuploid opens a conversation about a further cycle, donor eggs, or adoption. A high-risk NIPT result opens a conversation about diagnostic testing, and depending on results, about all available options going forward. Information is not an ending. It is the beginning of an informed decision.

Myth: Genetic testing of embryos means selecting a designer baby.

PGT-A selects for chromosomal normality — specifically, the correct number of chromosomes. It does not and cannot select for physical traits, intelligence, personality, height, eye colour, or any characteristic other than the presence or absence of specific chromosomal or genetic conditions. The goal of PGT-A is a healthy baby. That is the only goal.

What Should You Do If You Are Over 35 and Planning a Family?

If You Are Planning to Try Naturally or Are Already Pregnant

Discuss genetic screening with your obstetrician or fertility specialist early in pregnancy. First trimester combined screening should be offered to all pregnant women over 35. Ask specifically about NIPT — for women over 35, NIPT is the most accurate non-invasive screening option available and is recommended as first-line screening. If you have a family history of a genetic condition — in yourself, your partner, or either family — discuss carrier testing and genetic counselling before or early in pregnancy. Understand the difference between screening and diagnosis, and if a screening result returns elevated risk, discuss whether diagnostic testing is appropriate for your situation.

If You Are Undergoing or Considering IVF After 35

Ask your fertility specialist about PGT-A as part of your IVF cycle planning. If you or your partner carry a known genetic condition, ask about PGT-M and initiate this conversation as early as possible — probe development takes 3 to 6 months and should begin before your IVF stimulation cycle. If previous IVF cycles have resulted in unexplained implantation failure or early miscarriage, consider PGT-A on your next cycle to determine whether chromosomal aneuploidy was a contributing factor. Ensure your clinic performs trophectoderm biopsy using validated technique by trained senior embryologists. After a successful IVF transfer, still consider NIPT in pregnancy — PGT-A significantly reduces chromosomal risk but does not eliminate it entirely, and ongoing prenatal screening is complementary to, not replaced by, preimplantation testing.

Frequently Asked Questions

If PGT-A shows all my embryos are abnormal, what happens next?

A cycle in which all embryos are aneuploid provides important clinical information: it confirms that chromosomal aneuploidy is a factor in your situation, and it may influence decisions about protocol changes in the next cycle, the number of eggs to aim for in subsequent cycles, or whether donor egg IVF is the most efficient path forward. At Urvara, this result is reviewed in a dedicated consultation with our senior team, and a clear, individualised plan is developed. It is not a dead end. It is a redirection.

Does PGT-A affect the health of the baby born?

Extensive follow-up data on children born from PGT-A cycles shows no difference in physical health, developmental outcomes, or birthweight compared to children born from untested IVF cycles. The biopsy removes cells from the trophectoderm (future placenta), not the inner cell mass (future baby), and the embryo fully compensates for this small cell loss during subsequent development.

Can I have NIPT if I am pregnant after IVF?

Absolutely, and we recommend it. NIPT is highly informative after IVF pregnancy, although the result interpretation requires attention in certain circumstances — for example, in twin pregnancies or in cases involving a vanishing twin. Our team coordinates NIPT for all our IVF patients who wish it, and we interpret results with awareness of the specific IVF context.

My partner and I are both beta-thalassaemia carriers. What are our options?

As beta-thalassaemia carrier couples, you have a 25 percent chance with each natural pregnancy of conceiving an affected child with severe thalassaemia major. PGT-M in an IVF cycle allows the embryos to be tested for the specific thalassaemia mutations carried by both partners, identifying unaffected embryos for transfer. This completely prevents the birth of an affected child in the IVF cycle. Urvara has significant experience managing PGT-M cycles for thalassaemia carrier couples — please speak with our team as early as possible, as probe preparation takes time.

Is genetic testing covered by insurance in India?

Coverage varies by insurer and policy, and this is an area that is evolving. At Urvara, our team will help you understand the cost of each genetic testing option and, where relevant, assist with documentation required for insurance queries. We believe cost should not be a barrier to accessing information that could prevent serious genetic disease or improve IVF outcomes, and we discuss financial planning as part of every consultation that involves genetic testing.

Conclusion

Genetic testing can feel overwhelming — a long list of acronyms, statistics, and decisions arriving at a moment when you are already carrying enormous emotional weight. At Urvara Fertility Centre, we break this down step by step, with patience and without jargon, because we believe every patient deserves to fully understand every choice they make. You are not navigating this alone. Our clinical, embryological, and counselling teams are here for every conversation — however many it takes.

If you are over 35, undergoing IVF, or carrying a known genetic condition, a consultation with Urvara's clinical and genetic counselling team will give you the clarity you deserve. Every question is welcome. Every conversation is confidential.

Medical Disclaimer

This blog is intended for general health education and informational purposes only. It does not constitute medical advice, genetic counselling, or a personalised treatment plan. Statistics cited reflect published literature and clinical experience at time of publication and may vary by individual patient profile. Please consult the clinical team at Urvara Fertility Centre or a qualified fertility and genetics specialist for advice specific to your situation.