Evidence-Based Fertility Supplements: Nutrients for Egg Quality to support natural fertility and getting pregnant in women over 35
Introduction
It is a reality that aging is one of the biggest contributors to fertility issues in women. It is also a reality that more women are choosing to try for children later in life.
Women are born with a certain number of eggs (oocytes) – about 1 to 2 million eggs.
This number falls to around 300,000 to 500,000 by puberty and continues to decrease each year. After age 30 both egg quantity (ovarian reserve) and egg quality decrease significantly:
· By age 30 a woman has roughly 10% of the eggs she was born with left
· By age 37 this decreases to 2 to 3%
· age 40 only about 1% remain
Guidelines often recommend seeking fertility help after 6 months of trying if you’re over 35 (as opposed to 12 months for younger women). In reproductive medicine, 35 is the main cutoff when doctors start classifying pregnancy as “advanced maternal age.”
At this point, it is important to highlight that natural conception is possible after age 35 or 40 and that natural conception is possible even with very few eggs. But egg quality is crucial!
How do doctors measure ovarian reserve?
While it is impossible to count the total number of eggs directly, doctors estimate ovarian reserve using tests such as:
· Anti-Müllerian Hormone (AMH) blood testing
· Antral Follicle Count (AFC) using ultrasound
If you are trying to conceive and over age 35 or 40, your reproductive doctor may recommend additional testing such as
· FSH (follicle stimulating hormone) & estradiol
· Thyroid testing
How to improve fertility after 35 and 40
Lifestyle is crucial - start as early as possible!
Lifestyle plays a major role in reproductive health and egg quality. The earlier these habits are implemented, the better.
1. Maintain a healthy weight
Both underweight and overweight can disrupt ovulation.
2. Exercise - Aim for 20–30 minutes of moderate physical activity most days.
3. Sleep – aim for 7 to 9 hours of sleep in complete darkness every night to improve hormone and metabolic health
4. Stress reduction – Chronic stress may affect ovulation. Helpful strategies include mindfulness, yoga, meditation, even a walk with a friend
5. Avoid smoking - Smoking accelerates ovarian aging and egg depletion.
6. Moderate or no alcohol – 3 to 4 drinks max spread throughout the week but ideally avoid alcohol while actively trying to conceive.
7. Moderate or no caffeine - 200mg is a sensible limit which is 2 cups of coffee
8. Minimise environmental toxins (microplastics BPA, pesticides) – avoid heating food in plastic containers, plastic utensils – choose glass or stainless steel when possible
9. Track Ovulation
10. Manage conditions that affect fertility:
o Polycystic Ovary Syndrome (PCOS)
o Endometriosis
o Thyroid Disease
o Uterine Fibroids
11. Consider Fertility Treatments Earlier
If you are over 35 or 40 and trying to conceive naturally with no success, fertility treatments can help:
· Ovulation induction medications
· IUI (Intrauterine Insemination)
· IVF (In Vitro Fertilization), including ICSI
After 40, many doctors recommend considering IVF sooner, because success rates per cycle are higher than waiting with natural attempts.
12. Fertility Supporting nutrition
Foods that support fertility:
· Leafy greens e.g. spinach, kale, broccoli
· Fatty fish e.g. salmon, sardines, mackerel
· Nuts and seeds especially linseed, chia seed and walnuts
· Whole grains e.g. oats, wholemeal pasta,
· Berries e.g. blueberries, strawberries, raspberries etc.
Foods that reduce fertility:
· Highly processed foods e.g. packaged snacks, mass-produced bread, sausages, ready-meals etc.
· Trans fats e.g. beef, baked goods
· Excess sugar e.g. sweets, biscuits, soft drinks
Can supplements really improve fertility after 35?
Supplements cannot reverse ovarian aging or increase the total number of eggs. However, some evidence suggests they may help optimize the environment for egg development. In addition, some nutrients may help support ovulation, mitochondrial function, reproductive hormone balance, reduce oxidative stress, and improve the environment in which eggs mature, ultimately improving egg quality
The nutrients which have been shown to improve fertility outcomes in human research studies in women older than 35 or 40 include:
· Q10 – at least 100mg daily
· Alpha Lipoic acid – 600 to 800mg daily
· Carnitine at least 1000mg daily
· Myo-inositol 1,000 to 2000mg daily
· N acetyl-cysteine – 600mg daily
· Omega 3 – 1000mg daily
· Vitamin B9 (folate) 400mcg daily
· Vitamin D 50mcg (2,000 IU) daily
· Melatonin – 2 to 5mg every evening or get 7 to 9 hours sleep in complete darkness
Many fertility specialists recommend taking supplements for at least 3 months before attempting conception or fertility treatment, as egg development occurs over roughly 90–120 days.
Coenzyme Q10
A study of women aged 35–43 undergoing IVF reported that coenzyme Q10 supplementation for two months before treatment reduced aneuploidy* rates and increased pregnancy rates.
*Aneuploidy refers to an abnormal number of chromosomes in an egg or embryo, which increases the risk of miscarriage or genetic conditions
Coenzyme Q10 supplementation increased follicular fluid CoQ10 content and improved mitochondrial oxidative metabolism. These benefits were even greater in women over 35 years.
A 2020 review of 5 trials of Coenzyme 10 supplementation from Greek researchers reported that increased pregnancy rates, including in women with poor ovarian response and PCOS
A 2023 review of scientific studies published in the journal Human Fertility from UK researchers reported coenzyme Q10 supplementation could improve fertilization/embryo maturation rates and improve markers of oocyte quality in women aged 31 and over (many of the women were over 35).
Alpha Lipoic acid
A 2020 study in the Journal of Clinical Medicine reported that in overweight/obese women without PCOS (average age of 36) that myo-inositol + alpha lipoic acid + folic acid vs Resulted in improved egg quality compared to folic acid alone
Carnitine
A 2024 study reported that in 515 women with an average age of 35, carnitine supplementation led to:
· improved markers of ovarian function
· better follicular development
· higher ovarian response during IVF stimulation.
The authors concluded L-carnitine may help alleviate ovarian dysfunction and improve reproductive potential in women over 35.
Carnitine is involved in mitochondrial fatty-acid transport, which is crucial for egg energy metabolism.
Age-related egg quality decline is strongly linked to mitochondrial dysfunction.
Researchers think carnitine may help by:
1. Improving mitochondrial ATP production
2. Increasing fatty-acid oxidation in oocytes
3. Reducing oxidative stress
4. Improving endometrial receptivity.
These mechanisms are especially relevant in advanced maternal age fertility research.
A 2025 systematic review of 8 different randomized trials with over 1,000 women evaluated L-carnitine supplementation in fertility treatment. Carnitine supplementation increased:
· ovulation rates
· progesterone levels
· number of mature follicles
· clinical pregnancy rates.
Although this review included studies with women of various ages, the benefits of carnitine appear related to improved insulin sensitivity and improved mitochondrial metabolism which are highly relevant for age-related fertility decline.
In 2013, research from Hungary measured carnitine levels in follicular fluid during IVF and found that carnitine metabolism is closely linked with embryo developmental competence. These researchers suggested that supplemental L-carnitine could optimize early embryo development by improving cellular energy metabolism.
Myo-inositol
A 2012 study published in the journal Reproductive Biology and Endocrinology, Myo-compared myo-inositol and folic acid vs folic acid alone in women aged up to 40
Women taking myo-inositol:
· needed less rFSH hormone injections to reach egg maturation - This suggests the ovaries responded more efficiently.
· had fewer eggs retrieved - This sounds bad at first, but IVF success depends more on egg quality than quantity
· Slightly better implantation - Embryos from the myo-inositol group may have implanted slightly more often
· Pregnancy rates were the same - There was no significant difference in pregnancy rates between groups. So despite having fewer eggs, the myo-inositol group still achieved similar outcomes.
Based on this study and additional research with myo-inositol, supplementing with myo-inositol might:
· Make ovaries more sensitive to stimulation
· Reduce the amount of fertility drugs needed
· Possibly improve egg quality
· Maintain normal pregnancy rates
So instead of producing many eggs, the body might produce fewer but potentially better ones.
A 2015 study published in the Journal of Ovarian Research Myo-inositol supplementation in women age of 30 to 42 led to:
· higher number of mature eggs capable of fertilization
· higher ovarian sensitivity index
· improvement in ovarian sensibility to gonadotropin medications
In a 2020 study published in Journal of Gynecology Obstetrics and Human Reproduction, myo-inositol supplementation in women with an average age of 38 resulted in improved fertilization rate
· improved embryo quality
· higher pregnancy rate
in a 2021 study published in the journal Reproductive Biology and Endocrinology, Myo-inositol supplementation in women with an average age of 35 led to :
· more oocytes retrieved,
· higher number of MII oocytes,
· higher number of embryos transferred,
· higher ovarian sensitivity index
· lower required dose of gonadotropin
· higher fertilization rate
· higher pregnancy rate
a 2022 study published in the International Journal of Reproductive Biomedicine reported the myo-inositol could
· increase the total number of eggs
· the number of high quality eggs
· increase clinical pregnancy
· increase live birth rates
A 2017 review of studies (meta analysis) of 13 trials involving over 1,400 women aged 31 to 36, that myo-inositol supplementation
· reduced the required amount of stimulation drugs
· improved the quality of embryos
· increased clinical pregnancy rate
Vitamin B9
A 2014 study From Harvard examined 232 women (average age of 35) and reported that higher folate intake from diet+ supplements was associated with higher rates of
· fertilized egg implantation,
· clinical pregnancy,
· live birth.
A 2022 from the Environment and Reproductive Health Study among 552 women (average age 35) and reported that ‘higher intake of folate, particularly from supplements, was associated with higher ovarian reserve as measured by AFC (antral follicle count)
Another prospective study (BioCycle Study) examined hormonal cycles in women aged 18 to 44 and found that higher supplemental folate was associated with
· Higher luteal progesterone (this suggests health ovulation)
· Reduced likelihood of ovulation failure
These studies highlight the importance of folate for all but especially for women over 35 with roles such as
· improving oocyte quality
· improving embryo development
· reducing early embryo failure.
· Improving follicular development
· Improving ovarian aging markers
· ovulatory function
· luteal phase hormones
Vitamin D
A 2019 cohort study of 1,191 women aged up to 40 reported that the women with adequate vitamin D levels were more likely to achieve pregnancy and a live birth than the women with vitamin D deficiency
Another 2019 cohort study of 500 women, many of whom were in their mid 30s, reported that pregnancy rates were 65% lower in women with vitamin D deficiency. The researchers wrote: ‘Vitamin D deficiency and insufficiency are common in women undergoing assisted reproductive treatments. Vitamin D deficiency could be an important condition to treat in women considering fertility treatment’.
A 2022 study of vitamin D levels in women undergoing IVF with a median age of 36 reported that birth rates were 15% lower in women with vitamin D deficiency.
A 2025 study of over 300 women with a median age of 36 reported that pre-conception vitamin D deficiency is associated with an increased risk of hypertensive disorders in pregnancy in women undergoing in vitro fertilization with fresh embryo transfer.
In a large 2025 cohort study of 1,459 women. The researchers examined the effects of vitamin D levels of pregnancy rates in women older or younger than 35. Vitamin D deficiency was associated with significantly worse clinical pregnancy outcomes specifically in women over 35. The researchers concluded: ‘Vitamin D deficiency appears to lead to poorer clinical pregnancy outcomes in patients of advanced age’
Omega 3
A 2022 study of 900 women aged 30 to 44 reported that women using omega-3 supplements had 50% higher probability of conceiving per cycle compared with non-users
A 2026 study of 180 women aged 18 to 42 undergoing IVF assessed the effect of the pro-fertility diet + 1,000mg omega 3 daily for 60 days before IVF. The diet + omega 3 supplement led to
· significantly higher fertilization rates
· embryo formation rates
· increased number of embryos formed
· the proportion of grade A embryos was markedly higher
The ‘profertility diet’ is defined as:
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Less |
More |
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High pesticide fruit & veg |
Low pesticide fruit & veg |
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Meat |
Vitamin B9, B12 and D3 |
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Whole grains |
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Seafood |
|
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Dairy |
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Soy foods |
A 2023 trial with women with PCOS (average age = 34) reported that omega 3 supplementation increased pregnancy rates by 50% compared to placebo
Melatonin
Melatonin is best known as a sleep hormone but it also acts as a powerful antioxidant within ovarian follicles.
Several IVF studies have reported that melatonin supplementation may:
• reduce oxidative stress in follicular fluid
• improve oocyte quality
• increase fertilization rates
Because egg cells are highly sensitive to oxidative stress, melatonin may be particularly relevant for age-related fertility decline.
NAC (N-acetyl cysteine)
A 2022 study in the journal Frontiers in Medicine specifically examined the effect of NAC in in 200 ‘women with advanced age’, average age 38.
NAC significantly increased the number of high-quality blastocysts (better embryo development).
The Researchers also examined why. They found:
o increased glutathione levels in follicular fluid
o improved mitochondrial DNA copy number in granulosa cells (cells surrounding the egg).
The authors proposed that NAC improves egg quality by reducing oxidative stress in the ovarian follicle, which becomes more pronounced with age.
Final thoughts
Fertility naturally declines with age, but many women conceive successfully after 35 and even after 40.
Optimising lifestyle, nutrition, and key nutrients may help support egg quality, hormonal balance, and reproductive health.
For women trying to conceive later in life, combining healthy lifestyle habits, evidence-based supplements, and appropriate medical guidance may provide the best chance of successful pregnancy.
Frequently Asked Questions: Fertility After 35 and 40
1. Can you still get pregnant naturally after 35?
Yes. Many women conceive naturally after age 35. However, fertility gradually declines with age because both egg quantity (ovarian reserve) and egg quality decrease. While pregnancy is still possible, it may take longer compared with women in their 20s.
Doctors generally recommend seeking fertility advice after 6 months of trying if you are over 35.
2. Is it possible to get pregnant after 40 naturally?
Yes, natural pregnancy after 40 is still possible. However, the chances per cycle are lower because fewer eggs remain and the risk of chromosomal abnormalities increases with age.
Many women in their early 40s conceive naturally, but fertility treatments such as IVF may sometimes improve the chances of pregnancy.
3. What are the chances of getting pregnant at 35, 40 and 45?
Fertility varies between individuals, but average estimates per cycle are approximately:
• Age 30: about 20% chance per cycle
• Age 35: about 15% chance per cycle
• Age 40: about 5–10% chance per cycle
• Age 45: very low without fertility treatment
These numbers vary depending on overall health, ovarian reserve, and partner fertility.
4. What causes fertility to decline with age?
Several biological factors contribute to age-related fertility decline:
• Reduced number of eggs in the ovaries
• Reduced egg quality
• Increased risk of chromosomal abnormalities
• Hormonal changes affecting ovulation
• Higher risk of conditions such as fibroids or endometriosis
One important factor is mitochondrial function, which affects the energy production required for egg maturation and embryo development.
5. What tests can check fertility after 35?
Doctors often evaluate fertility using several tests:
• AMH (Anti-Müllerian Hormone) – estimates ovarian reserve
• Antral Follicle Count (AFC) – ultrasound measurement of follicles
• FSH and estradiol – hormone levels related to ovarian function
• Thyroid function tests
Your doctor may also recommend semen analysis for the male partner, since male factors contribute to around 40–50% of infertility cases.
6. How long should I try before seeing a fertility specialist?
Guidelines generally recommend:
• Under 35 → try for 12 months before seeking help
• Over 35 → try for 6 months
• Over 40 → consider seeking advice immediately
Earlier evaluation can help identify issues and improve treatment success.
7. Can lifestyle changes improve fertility after 35?
Yes. Lifestyle factors can influence hormone balance, ovulation, and egg quality. Helpful strategies include:
• maintaining a healthy weight
• regular physical activity
• good sleep habits
• avoiding smoking
• limiting alcohol
• managing stress
• eating a nutrient-rich diet
These factors may not reverse aging but can help optimise reproductive health.
8. Can supplements improve egg quality?
Some nutrients may support egg development and reproductive health, particularly those involved in mitochondrial function and antioxidant defence.
Commonly studied supplements include:
· Coenzyme Q10
· Alpha lipoic acid
· Myo-inositol
· Omega-3 fatty acids
· Vitamin B9 (Folate)
· Vitamin D
· NAC
· Carnitine
However, supplements cannot increase the number of eggs or fully reverse age-related fertility decline.
9. Does egg quality decline after 35?
Yes. Egg quality gradually declines with age. This is partly due to increased chromosomal abnormalities (aneuploidy) and changes in mitochondrial energy production within the egg.
Lower egg quality can increase the risk of miscarriage and reduce the chances of successful fertilisation.
10. When should IVF be considered after 40?
Doctors may recommend considering IVF sooner for women over 40 because natural conception rates per cycle are lower.
IVF can improve pregnancy chances by:
• stimulating multiple eggs
• selecting the healthiest embryos
• enabling genetic testing in some cases
However, success rates still depend on individual factors such as ovarian reserve and overall health.
11. How long does it take for eggs to mature before ovulation?
Egg development takes approximately 90–120 days before ovulation. This process is called folliculogenesis.
Because of this, lifestyle changes and supplements are usually recommended for at least 3 months before trying to conceive or before fertility treatment.
12. Does male fertility affect chances of pregnancy after 35?
Yes. Male fertility plays a major role in conception. Sperm quality—including count, motility, morphology, and DNA integrity—can significantly influence pregnancy success.
Male factors contribute to around half of infertility cases, so both partners should be evaluated when trying to conceive.
Male fertility also plays an important role
If you are a woman trying to conceive, ensure your male partner has also had a fertility evaluation, is following a fertility friendly lifestyle and check our these blogs:
Nutrients for Male Fertility, Sperm Quality and sperm count - The Science
Nutrients for Male Fertility, Sperm Quality and sperm motility - The Science
Nutrients for Male Fertility, Sperm Quality and sperm morphology - The Science
Nutrients for Male Fertility, Sperm Quality and sperm DNA fragmentation - The Science
Nutrients for Male Fertility, Sperm Quality and varicocele - The Science
In addition to advanced age, other common conditions contributing to fertility issues in women, include:
Assisted reproduction i.e. IVF, ICSI, IUI
Antiphospholipid syndrome
Diminished ovarian reserve (DOR)
Endometriosis
Egg quality
Fibroids
Hypothalamic amenorrhea
Low AMH
Lupus
Overweight & obesity
PCOS
Premature ovarian insufficiency (POI)
Thyroid issues, especially Hashimoto's or autoimmune thyroiditis
Miscarriage and recurrent pregnancy loss
Please note: This article is for educational purposes only and does not replace personalised medical advice from a qualified healthcare professional.
· Not all supplements are appropriate for everyone. Always consult your GP or fertility specialist before starting supplements, particularly if undergoing assisted reproductive treatment.
· Timing matters – lifestyle changes, including supplements are recommended for at least 3 months before conception. This is because a woman’s eggs take approximately 3 to 4 months (roughly 90-120 days) to mature before ovulation, in a process known as folliculogenesis.
· Dosing matters – scientific research has reported benefits of certain doses. It is important to seek out and consume these doses to get the same benefits.
