Recommendations for research
The guideline committee has made the following recommendations for research.
Key recommendations for research
1 Treatments based on endometrial receptivity testing
Do treatments for identified endometrial abnormalities related to the microbiome or microbiological analysis (such as antibiotics to treat endometritis or microbiota transplantation) improve reproductive outcomes for people undergoing assisted reproduction? [2026]
For a short explanation of why the committee made this recommendation for research, see the rationale section on endometrial receptivity testing.
Full details of the evidence and the committee's discussion are in evidence review D: endometrial receptivity testing.
2 Subclinical hypothyroidism
What are the benefits and harms of levothyroxine for the treatment of subclinical hypothyroidism in women, and trans men and non-binary people with female reproductive organs who are receiving fertility treatment? [2026]
For a short explanation of why the committee made this recommendation for research, see the rationale section on subclinical hypothyroidism.
Full details of the evidence and the committee's discussion are in evidence review B: subclinical hypothyroidism.
3 Testicular tissue cryopreservation
What is the safety and clinical and cost effectiveness of testicular tissue cryopreservation for fertility preservation for prepubertal and peripubertal boys who are undergoing medical treatment, or who have a medical condition, that is likely to impair their fertility? [2026]
For a short explanation of why the committee made this recommendation for research, see the rationale section on fertility preservation for medical indications.
Full details of the evidence and the committee's discussion are in evidence review R: fertility preservation.
4 Hormone treatments for male factor fertility problems
What is the effectiveness of anti-oestrogens or gonadotrophins in men, trans women and non-binary people with azoospermia or impaired or reduced semen parameters (non-azoospermia) with normal or high follicle-stimulating hormone (FSH) and low testosterone?
For a short explanation of why the committee made this recommendation for research, see the rationale section on medical management of male factor fertility problems.
Full details of the evidence and the committee's discussion are in evidence review U: hormone treatment for male factor fertility problems.
5 Treatment for varicocele
What is the clinical and cost effectiveness of radiological, surgical and microsurgical treatments for fertility problems associated with varicocele?
For a short explanation of why the committee made this recommendation for research, see the rationale section on varicocele.
Full details of the evidence and the committee's discussion are in evidence review X: treatments for varicocele.
Other recommendations for research
Expectant management before IVF
What is the optimum period of expectant management for women, and trans men and non-binary people with female reproductive organs of different age groups before invasive treatment such as in vitro fertilisation (IVF) is considered? [2013]
Why this is important
Where there is no known cause for infertility, expectant management increases the cumulative chances of successful conception. However, the chances of a live birth both by spontaneous conception and by using assisted reproductive technology decline with advancing age because of decreasing ovarian reserve. If there were better evidence, it might be possible to customise the period of expectant management based on age, including longer periods of expectant management for younger people.
Long-term safety of ovarian stimulation and ovulation induction in women, and trans men and non-binary people
Is there an association between ovulation induction or ovarian stimulation and adverse long-term (over 20 years) effects in women? [2013]
Why this is important
People need to be reassured that it is safe to undergo ovulation induction and ovarian stimulation, and that these interventions will not lead to significant long-term health issues, especially ovarian malignancy. Both treatments are common in managing infertility. The use of ovarian stimulation in IVF is particularly important, as IVF is the final treatment option for most causes of infertility. During the review for the 2013 guideline update, the guideline development group commented on the paucity of long-term research on the subject, despite the fact that the treatments have been established practice for over 30 years. The longest length of follow-up in the studies reviewed was 20 years, and the larger studies had shorter follow-up periods.
Long-term effects of IVF with or without ICSI in children
What are the long-term (over 20 years) effects of IVF with or without intracytoplasmic sperm injection (ICSI) in children in the UK? [2013]
Why this is important
This topic is important in informing patients, service providers and society at large about the potential long-term safety of assisted reproduction. Both IVF and ICSI involve manipulation of egg and sperm in the laboratory, with impacts on the development of the subsequent embryo. However, while the first successful live birth following IVF was over 30 years ago, there is relatively little long-term research on the subject. In the review undertaken in this guideline update, the longest length of follow-up in the studies reviewed was 20 years, and the larger studies had shorter follow-up periods.