A Deep Dive into Fertility with Dr. Nalini Mahajan

Dr. Nalini Mahajan is an infertility specialist and gynaecologist with over 51 years of overall medical experience, including 45 years as a specialist. She holds an MBBS and an MD in Obstetrics and Gynaecology, and has spent more than 35 years working specifically in the field of infertility and assisted reproduction, both in clinical practice and academic settings.

Q) Why does IVF need to be personalized, and what factors determine the best approach for each patient?

A) The first and most important question is: Does the patient even need IVF? Before anything else, a thorough assessment is essential to determine whether IVF is the right course of action, because there are other fertility treatments that might be more suitable depending on the case.

Once IVF is deemed necessary, personalisation becomes crucial because each patient is different. They may have different reasons for infertility—some may have female-factor infertility, others male-factor, and some both. For instance, if male-factor infertility is present, the doctor may opt for ICSI (Intracytoplasmic Sperm Injection) instead of standard IVF.

Another key factor is the woman’s ovarian reserve. This significantly influences the type of stimulation protocol chosen—what medications to use, what dosage, how closely to monitor, and how her body is expected to respond during a typical menstrual cycle.

Although IVF is increasingly being treated like an assembly-line process, this is fundamentally flawed. In reality, every patient’s body reacts differently to hormonal medications and procedures. That’s why it’s vital to assess each individual holistically before starting treatment—by understanding their hormonal patterns, menstrual cycle behavior, and overall reproductive health—to tailor the IVF approach specifically to them.

Q) What can women do to enhance fertility? Also, do supplements like CoQ10 actually help?

A) The most fundamental answer to improving fertility is lifestyle management. While many people look for quick fixes or shortcuts, the truth is that your daily habits play a major role in reproductive health.

One of the most important—but often overlooked—factors is age. Your biological age, not how young you feel. You might feel 25 at 45, but unfortunately, your ovaries don’t. In fact, the ovaries are among the first organs in the body to age. As a woman gets older, not only does the number of eggs (ovarian reserve) decrease, but so does their quality—leading to more chromosomal abnormalities, higher miscarriage rates, and reduced chances of conception, even with interventions like IVF.

Many women today delay family planning due to career, education, or personal goals. By the time they’re ready, fertility has already declined significantly—and that’s when the struggle begins. So the earlier women start thinking about this, the better.

Apart from age, lifestyle factors also heavily influence fertility. This includes:

• A balanced diet

• Regular exercise

• Adequate sleep

• Avoiding smoking and excessive alcohol

• Minimizing stress

• Being physically present with your partner during the fertile window

Now, regarding supplements like CoQ10—they can help, but only to a certain extent. They may improve egg quality slightly or correct nutritional deficiencies, but they cannot reverse aging or change your biology. So while they can be supportive, they’re not miracle solutions.

In short: take care of your body, understand your biology, and don’t underestimate the impact of time.

Q) Are AMH and FSH still the best markers for ovarian reserve testing?

A) Today, the best markers for assessing ovarian reserve are AMH (Anti-Müllerian Hormone) and AFC (Antral Follicle Count). These two provide a more accurate picture of the number of eggs a woman has.

FSH (Follicle-Stimulating Hormone), on the other hand, is no longer considered a reliable standalone marker—except in certain cases. For example, if a woman has a low AMH and AFC and a high FSH, that’s typically a red flag indicating diminished ovarian reserve and potentially poor egg quality.

However, in younger women, even if the follicle count is slightly lower, their FSH levels are usually still within a healthy range, which suggests that the eggs they do have are more likely to be of good quality.

So while FSH can still offer insight, especially in cases of suspected poor ovarian response, AMH and AFC remain the most dependable tools for evaluating ovarian reserve today.

Q) How does sperm quality affect IVF outcomes? Are there lifestyle changes men should consider?

A) Sperm quality does affect IVF outcomes. Fertilisation errors may occur, and the development of the embryo can be impacted—especially after Day 3, when the embryonic genome gets switched on. That’s when the male factor tends to show up more clearly, and you may find that the embryo doesn't grow very well. If the sperm quality is not good, you may not have very good embryos.

Sometimes, because the tests we have for sperm are so basic, everything may seem absolutely fine, and yet you could end up with no fertilisation at all. So there’s a lot more to the sperm story that we still don’t fully understand.

Q) How does aging biologically impact egg and sperm quality beyond just chronological age?

A) When it comes to eggs, if you’re 40, your eggs are also 40 years old. All the eggs a woman will ever have are formed by six months of intrauterine life, and from birth onwards, they only decline in number. After 35, that decline becomes even more rapid.

What’s inside the egg—like the chromatin and the mitochondria—also ages. This aging contributes to meiotic errors during fertilisation, which is why older eggs are more likely to result in abnormal embryos and higher miscarriage rates.

As for sperm, it was long believed that age had little to no effect. But now it's being recognized that in men over 40, sperm does start to show age-related decline. This has been linked to poorer fertilization, weaker embryo quality, and even a possible association with autism.

Q) What are the most common genetic or hormonal disorders that affect fertility?

A) PCOS is the most common, and it's becoming more and more prevalent in our country because of lifestyle changes. So PCOS is one of the most common causes.

Endometriosis is not so much a hormonal disorder as it is an immune-altered state of the body, where it is unable to handle the back flow of menstrual blood. There are other theories behind it as well, but this is one of them.

But yes, PCOS, I would say, is perhaps the most common.

Q) How do autoimmune conditions affect fertility, and what precautions should women take before IVF?

A) Hashimoto's may not necessarily affect fertility, unless you haven’t corrected your thyroid status—because that’s what really impacts fertility. If your thyroid is well-controlled, it may or may not influence pregnancy loss more than infertility.

The immune system plays a role in implantation, and unfortunately, that’s a big grey area. We still don’t fully understand what happens once the embryo enters the uterus. Certain immune changes should take place to allow the uterus to accept the embryo, since it carries foreign genetic material from the father. Normally, if I were to put a kidney in you, your body would reject it unless it’s matched. But the uterus is an immune-protected site. It’s protected because there are changes that happen in the mother—both at the blood level and more so at the uterine level—which allow the embryo to implant and grow.

So, autoimmune disorders can affect implantation. That’s one. The other thing is that many autoimmune disorders affect the ovary and reduce ovarian reserve. One thing we’re seeing a lot of today—but don’t yet have a clear answer for—is why so many young women are showing such low ovarian reserve.

Q) Do you recommend egg freezing for everybody, or is it on a case-by-case basis?

A) The first thing I’d like to say about egg freezing—since it’s become so popular—is that people think it’s some kind of sure-shot way to get pregnant whenever they want, just because the eggs are frozen. But it’s not. If you freeze 20 eggs, you may only have about a 60% chance of having a successful pregnancy.

So, the counselling has to be pro-fertility counselling, not just fertility oocyte freezing counselling. You have to explain to the person that this is not some miracle that guarantees a baby. If circumstances are such that you can’t have a baby right now, then yes, egg freezing is like a backup insurance plan—but it is not a guarantee. That must be made very clear.

You also need a certain number of oocytes, and ideally, egg freezing should be done at a younger age. As I mentioned earlier, after 35, egg numbers start dropping and quality deteriorates. So, technically, the best time to freeze would be around 32 or 33. But when you do it at that young an age, there’s also an ethical question—you’re doing an intervention for someone who may never need it.

There’s a lot of ethical debate around that. But yes, if someone has to do it, then between 33 and 35 is ideal for Indian women. Abroad, they take it up to 37, but their ovarian reserves tend to be much better than ours.