10 IVF myths: what the evidence actually says

In vitro fertilisation has been used for decades, yet many beliefs surrounding IVF remain surprisingly persistent.

Patients are still advised to stay in bed after embryo transfer. A failed transfer may immediately be attributed to "immune incompatibility." Low AMH is interpreted as poor egg quality. Two embryos are assumed to provide twice the chance of success. And PGT-A is sometimes perceived almost as a guarantee of pregnancy.

Evidence-based reproductive medicine should distinguish between three very different things: a biologically plausible hypothesis; a statistical association; and evidence that an intervention actually increases the probability of live birth.

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Myth 1. You need bed rest after embryo transfer

This is probably one of the most persistent myths in IVF. Patients may worry that walking, using the bathroom or travelling home could somehow displace the embryo or cause it to "fall out" of the uterus.

The evidence does not support this. The ASRM guideline "Performing the Embryo Transfer" reviewed studies evaluating bed rest following embryo transfer and found no convincing evidence of benefit.

One randomised controlled trial in donor-oocyte cycles included 240 women undergoing their first IVF cycle. Following embryo transfer, one group remained in bed for 10 minutes, whereas the other mobilised immediately. The live birth rate was 41.6% after 10 minutes of bed rest and 56.7% after immediate mobilisation (P=0.02).

Based on the overall evidence, ASRM concluded that bed rest after embryo transfer should not be recommended — Grade A.

Clinical takeaway: after an uncomplicated embryo transfer, patients may stand up, walk, use the bathroom, travel home and continue normal daily activities. Bed rest does not increase implantation or live birth rates.

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Myth 2. Transferring two embryos doubles the chance of having a baby

Double embryo transfer may increase pregnancy probability per individual transfer in some circumstances, but it also substantially increases the risk of multiple pregnancy, which carries:

• preterm birth

• low birth weight

• pre-eclampsia

• gestational diabetes

• maternal hospitalisation

• neonatal complications

Modern ART therefore increasingly focuses on single embryo transfer (SET). The ESHRE Guideline on the Number of Embryos to Transfer during IVF/ICSI emphasises that the objective of infertility treatment should be a healthy pregnancy and birth while minimising the risk of multiple pregnancy.

The same principle applies in surrogacy. Transferring two embryos to a gestational carrier in an attempt to maximise pregnancy probability simultaneously increases obstetric risks for the surrogate and the future children.

Conclusion: two embryos do not mean twice the probability of taking home a healthy baby. They primarily mean a substantially greater risk of twin pregnancy.

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Myth 3. A 5AA or euploid embryo guarantees pregnancy

Morphological grading describes the developmental appearance of the blastocyst. PGT-A provides information regarding the chromosomal status of the sampled trophectoderm cells. Both provide valuable prognostic information, but neither guarantees implantation.

The 2026 ASRM Committee Opinion on recurrent implantation failure emphasises that even after transfer of good-quality and/or euploid blastocysts, implantation is not guaranteed.

ASRM recommends considering RIF according to the cumulative probability of implantation, rather than automatically diagnosing it following one unsuccessful transfer. Current evidence suggests that RIF may become relevant after approximately 3–6 unsuccessful euploid embryo transfers, depending on the individual clinical circumstances. Implantation depends on a number of factors at once:

• intrinsic embryo developmental competence

• morphology

• day of blastocyst development

• uterine cavity pathology

• endometrial and hormonal factors

• laboratory conditions and transfer technique

• unavoidable biological variability

Conclusion: a euploid embryo has a favourable prognosis, but euploid does not mean 100% implantation.

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Myth 4. PGT-A increases live birth rates in every IVF patient

PGT-A allows embryos to be prioritised according to chromosomal status. However, PGT-A does not create additional euploid embryos and does not repair aneuploid embryos.

A large multicentre randomised controlled trial in China included 1,212 women aged 20–37 years with at least three good-quality blastocysts. Cumulative live birth was 77.2% with PGT-A and 81.8% with conventional IVF. Pregnancy loss, however, was lower in the PGT-A group: 8.7% versus 12.6%.

The ASRM Committee Opinion on PGT-A (2024) concludes that the value of PGT-A differs between patient populations and that universal use to increase cumulative live birth in every IVF patient is not supported by current evidence.

Conclusion: PGT-A is primarily an embryo-selection tool, not a treatment that improves embryo quality.

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Myth 5. ERA should be performed after one or two failed transfers

Endometrial receptivity testing analyses endometrial gene expression and attempts to identify the optimal duration of progesterone exposure before embryo transfer. However, biological plausibility does not necessarily translate into clinical benefit.

A major double-blind RCT included 767 women. In 381 patients, euploid embryo transfer timing was guided by receptivity testing; 386 underwent transfer at standard timing. Personalised timing did not significantly improve live birth rate.

A subsequent analysis found an AUC of 0.52 for predicting implantation failure. The ASRM Committee Opinion 2026 therefore concludes that there is insufficient evidence to support routine ERA testing in patients with RIF. ESHRE takes a similarly cautious position.

Conclusion: one or several unsuccessful transfers do not, by themselves, prove the existence of a displaced implantation window.

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Myth 6. Failed implantation can be diagnosed through NK cells or KIR/HLA-C testing

The immune system unquestionably plays an important role in implantation, decidualisation and placentation. However, there is a major difference between saying "The immune system participates in implantation" and "This immune test can identify the cause of this patient's failed IVF cycle."

Natural killer cells, cytokines, KIR/HLA-C interactions and other aspects of the maternal–fetal immune interface remain active areas of research. However, many currently available tests lack sufficient standardisation and clinical validation.

The ESHRE Good Practice Recommendations on Recurrent Implantation Failure do not recommend routine peripheral or uterine NK-cell testing.

Conclusion: reproductive immunology is an important scientific field, but the existence of immune mechanisms in implantation does not automatically make every immune biomarker a clinically validated IVF test.

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Myth 7. Intralipid, IVIG and other "immune infusions" are proven to improve implantation

Some small trials and meta-analyses have reported potentially favourable results with intralipid. For example, an analysis of five RCTs reported clinical pregnancy RR 1.55 (95% CI 1.16–2.07) and live birth RR 1.83 (95% CI 1.42–2.35).

However, small sample sizes, heterogeneous definitions of RIF, different treatment protocols and methodological limitations mean that the evidence has not been considered sufficiently robust for routine clinical use. ESHRE therefore does not recommend intravenous intralipid infusion for RIF. The ASRM Committee Opinion 2026 similarly states that evidence for intravenous fat emulsion and G-CSF is insufficient, and IVIG is not recommended for treatment of RIF.

Conclusion: a positive meta-analysis of several small studies does not automatically establish a treatment as standard clinical care.

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Myth 8. Everyone needs heparin after embryo transfer "to improve blood flow"

The ASRM Committee Opinion 2026 notes that studies evaluating heparin or LMWH in women without antiphospholipid syndrome have produced conflicting results, without clear evidence of clinical benefit. ASRM therefore concludes that there is insufficient evidence to support routine anticoagulation in RIF.

This does not mean that aspirin or LMWH should never be prescribed. There are separate obstetric, haematological and medical indications for these medications.

Conclusion: "embryo transfer performed" does not equal "heparin indicated". Anticoagulants should be prescribed for appropriate medical indications, not automatically as "implantation medication".

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Myth 9. AMH measures egg quality

AMH and antral follicle count are predominantly markers of quantitative ovarian reserve and are useful predictors of ovarian response and expected oocyte yield.

According to the ASRM Committee Opinion on ovarian reserve testing, AMH and AFC predict oocyte quantity considerably better than oocyte quality, clinical pregnancy or live birth. ASRM emphasises that female age is a substantially stronger predictor of reproductive success than ovarian reserve markers.

Even extremely low AMH should not, by itself, be used as a reason to deny a patient IVF.

A simplified way to understand it: AMH mainly helps answer "How many oocytes might we expect?", while age provides considerably more information about "How likely are we to obtain a reproductively competent oocyte?" Low AMH does not automatically mean poor egg quality.

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Myth 10. With young donor eggs, the recipient's age no longer matters

This statement requires particularly careful interpretation. It is partly true when discussing oocyte ageing, but becomes misleading when applied to the entire reproductive and obstetric process.

Three separate concepts should be considered: the age of the oocyte; the age of the recipient; and the age and health of the woman carrying the pregnancy.

Oocyte age is a major determinant of embryological reproductive potential

The age-related decline in female fertility is driven to a large extent by oocyte ageing, including increasing meiotic errors and embryonic aneuploidy. This is why using oocytes from a young donor can largely overcome the decline in reproductive potential associated with ageing of the recipient's own oocytes.

The ASRM Ethics Committee Opinion on Assisted Reproduction with Advancing Paternal and Maternal Age (2025) recognises that oocyte donation can circumvent much of the age-related decline in implantation and birth rates and substantially restore pregnancy potential beyond the natural reproductive years.

ASRM guidance on gamete and embryo donation recommends that oocyte donors should preferably be 21–34 years old. If a donor is older than 34, her age should specifically be discussed with the recipient because of its implications for cytogenetic risk and pregnancy rates.

A population-based study by Wang et al. analysed 3,889 donor-oocyte recipient cycles. Live birth rates according to donor age were <30 years: 24.1%; 30–34: 25.0%; 35–39: 20.7%; ≥40: 11.5%.

Compared with donors aged 30–34 years, the probability of live delivery was 18% lower with donors aged 35–39 years — adjusted rate ratio 0.82 (95% CI 0.71–0.96), and 54% lower with donors aged ≥40 years — adjusted rate ratio 0.46 (95% CI 0.29–0.73).

Another population-based cohort of 1,490 oocyte recipients found cumulative live birth rates by donor age: <30 years: 44.7%; 30–34: 43.3%; 35–37: 33.6%; 38–40: 22.6%; ≥41: 5.1%. In the same cohort, recipient age had no statistically significant effect.

Does this mean recipient age does not matter at all?

No. A large analysis of 27,959 fresh donor-oocyte IVF cycles from the Society for Assisted Reproductive Technology found relatively stable outcomes in younger recipient groups but declining implantation, clinical pregnancy and live birth at approximately 45 years and beyond.

In 2026, Crestani et al. analysed 2,760 single blastocyst transfers using donor oocytes in 1,774 women. After adjustment for several factors, women older than 49 years had a lower probability of live birth — OR 0.62 (95% CI 0.41–0.93) and approximately twice the odds of miscarriage — OR 2.07 (95% CI 1.16–3.69).

Cumulative live birth declined from approximately 80% among recipients aged 35–40 years to 62.5% among women older than 49 years in the uncensored analysis. These findings suggest that at very advanced recipient ages, uterine and/or systemic ageing may have an independent effect on reproductive outcomes even when donor oocytes are used.

Pregnancy risk is a separate issue

A young donor oocyte does not make the woman carrying the pregnancy physiologically younger. The ASRM Ethics Committee Opinion 2025 distinguishes between risks related to ageing gametes and the increasing health risks of gestating at an older age. With increasing maternal age, risks of hypertensive disorders, pre-eclampsia, gestational diabetes, caesarean delivery, preterm birth and other complications increase.

In gestational surrogacy, this distinction is especially clear. If an embryo is created using the oocyte of a 25-year-old donor, the relevant oocyte age remains 25 regardless of the age of the intended mother. The age and health of the gestational carrier primarily influence the gestational environment and obstetric risks. A young gestational carrier cannot correct a chromosomal abnormality already present in an embryo.

Conclusion: young donor oocytes can largely overcome the age-related decline in fertility caused by oocyte ageing, but they do not completely erase every effect of recipient ageing. At very advanced recipient ages, uterine and systemic ageing may independently reduce live birth and increase miscarriage risk, while pregnancy risks remain related to the age and health of the woman carrying the pregnancy.

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Perhaps the biggest myth: if a transfer fails, there must be a specific cause

After a negative pregnancy test, patients understandably ask: "Why did it fail?" But sometimes the most scientifically accurate answer is that we cannot identify one specific cause for an individual failed implantation event.

In 2026, ASRM proposed a probability-based approach to recurrent implantation failure. RIF should be considered after failure of the estimated number of good-quality blastocysts required to reach approximately a 95% cumulative probability of at least one positive pregnancy test. Current literature suggests that this may correspond to approximately 3–6 failed euploid embryo transfers, depending on the individual clinical situation.

When detailed review of the patient's history, previous IVF cycles and standard evaluation does not identify a clear correctable cause, extensive additional testing may be unnecessary. Proceeding with further embryo transfers can remain a reasonable strategy.

Not every negative transfer represents a disease. Not every negative transfer requires another test. And not every additional test increases the probability of live birth.

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Conclusion

Modern reproductive medicine should not be judged by the number of medications, investigations or procedures prescribed. The clinically meaningful goal is the highest reasonable probability of delivering a healthy child while minimising unnecessary risks to the patient, gestational carrier and future child.

Before adding another IVF test or treatment, three questions are worth asking: Is there a biologically plausible mechanism? Is there high-quality clinical evidence? And most importantly — has it been shown to improve live birth rate?

A "yes" to the first two questions does not automatically guarantee a "yes" to the third.

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This article is intended for educational purposes and should not replace individual medical assessment. Diagnostic and treatment decisions in IVF should be personalised according to age, reproductive history, infertility diagnosis, embryo characteristics, previous treatment outcomes and relevant medical conditions.