Sex hormones, fertility and sexuality
Infertility was believed to be a characteristic of all adults with Prader-Willi syndrome (PWS) until 1999, when the first documented pregnancy was reported in a woman with PWS. Subsequently another three cases worldwide have been documented of women with PWS becoming pregnant. As of this writing, there have been no reports of fertility in men with PWS.
Hypogonadism and fertility
Hypogonadism with low levels of sex hormones (oestrogen in women and testosterone in men) is very common in PWS. A tight interaction between hormones from the hypothalamus, the pituitary, and the ovaries in women or the testes in men, regulates the levels of sex hormones. A normal level of hormones and a normal function of involved glands is necessary for sexual development and fertility. A dysfunction in any of these glands will result in hypogonadism and decreased/absent fertility. Sex hormones are also important for the growth spurt in puberty, for the development of secondary sexual characteristics, body fat/lean muscle composition, bone mineral density, and quality of life. In addition to the well-established hypothalamic dysfunction in PWS, recent studies have associated the hypogonadism with impaired function of the ovaries and testes. Therefore, the flaw may lie along the continuum from complete primary (ovaries/testes) hypogonadism to complete central (hypothalamus/pituitary) hypogonadism.
In the majority of women with PWS menarche (first menstruation) is usually absent or delayed up to the late 20’s. When menstrual periods occur, they are often irregular and, accompanied by infrequent or absent ovulations. Pseudo-menstruations, where the uterine mucosa is excreted due to oestrogen production in fat tissue, are also seen. The presence of menstrual periods whether induced by treatment with oestrogen or of natural onset does not indicate fertility, unless ovulations occur. Thus, most women with PWS are infertile, although the hormonal levels required for potential fertility may be present in some. In men with PWS, viable spermatozoas (necessary for fertility) have not been described. In both genders obesity or being overweight can lead to or worsen hypogonadism and infertility, presumably due to the production of oestrogen in fat cells hampering the function of the hypothalamus and the pituitary. Similarly, treatment with oestrogen and testosterone suppresses the secretion of hormones from the hypothalamus and pituitary gland. Conversely, a significant weight loss or change in medication might increase the hormone levels; there are reports of fertility in some women on serotoninergic agents, like fluoxetine. Of note, there is evidence to suggest that some psychotropic medications interact with the hypothalamus, pituitary and gonadal steroids at the level of the cytochrome P450 enzymes in the liver, which could potentially decrease or increase fertility.
Fertility is best evaluated by measuring relevant hormones. Typically, in adults with PWS the pituitary hormone FSH (follicle stimulating hormone) will be high with low oestrogen and testosterone levels in females and males, respectively. However, depending on which hormone-secreting gland is not functioning appropriately, different hormone levels can be seen. For example, the hormone inhibin B, from the ovaries and the testes, is associated with potential fertility. In most adults with PWS, inhibin B is undetectable, indicating infertility, but in some women detectable levels have been found, and fertility might be possible. In principle, evaluation of fertility in men requires the study of the ejaculate, but due to sexual dysfunction, cognitive and behavioral problems, obtaining ejaculate is usually not feasible. It is unknown what percentage of men with PWS are capable of an ejaculation, but the Clinical and Scientific Advisory Board (CSAB) of IPWSO is aware of two men who were able to produce ejaculate, and examination of both their ejaculates was negative for sperm.
Sex hormone treatment
In both genders sexual hormone replacement may be important for developing an adult appearance, for enhanced bone mineral density, for optimal muscle and organ function, and for gender specific brain maturation, altogether leading to an improved quality of life. Before initiating replacement of sex hormones, blood tests measuring relevant hormones are needed. After puberty sex hormone treatment may not always be advised to the specific individual with PWS, and a balanced discussion of the potential benefits and risks should be held with the patient and their caretakers.
In women, the well-known risks associated with oestrogen supplementation should be considered, particularly thromboembolism, which is already an increased risk in PWS and in obesity, as well as the risk of breast cancer, and mood instability. In men, the effect of testosterone on mood and behaviour needs to be recognised, although these may be dose related. An individualised approach to hormone therapy is the key. The goal of testosterone or oestrogen supplementation in PWS might not be to achieve the levels defined as within the normal range for those without PWS. For many, lower doses of sex hormones are sufficient to obtain the positive effects of the treatment. Treatment must be carefully monitored and adapted to the patient’s needs, starting with a low dose followed by a gradual increase. Parents and caregivers should be carefully informed, especially about the body changes in men, for example face and body hair, and deepening of voice, and spot bleeding from the vagina in females. In women, an important distinction between treatment of hypogonadism and birth control management needs to be explained. Importantly, fertility will not be gained by treatment with oestrogen or testosterone.
Sexuality
Despite the hypogonadism, the desire to get married and have children is very common in adults with PWS. Many express strong romantic thoughts and demonstrate an interest in sexual experiences. Some, both women and men, express thoughts, fantasies and behaviours that mirror their desires, such as playing with dolls as adults. An adult with PWS may develop maternal or paternal feelings following the birth of a niece or nephew, or may instead experience jealousy that their own parents have an intense interest in the new grandchildren and give them more attention than they do their child with PWS.
Romantic relationships may be perceived in many different ways by persons with PWS, and it is important to differentiate fantasy from a more actionable situation. Some may exhibit magical thinking, claiming to be engaged to be married (for example to a well-known pop star) and indicating that a marriage date has been set, even though they have minimal contact with, or personal knowledge of, the identified person. Others may have a real girlfriend or boyfriend and describe a dating relationship of variable intensity; they may be content to display affection through telephone contact, hand holding and kissing without actual sexual contact. A few may enter what can be described as a serious relationship that might include sexual intercourse, often with a partner who does not have PWS.
First, it is important to evaluate their level of understanding of sexual function and “where babies come from.” Second, their understanding of the rules and responsibilities, boundaries, and personal safety around sexual behaviour must be explored. Finally, their knowledge of the risks of sexually transmitted diseases must be assessed. Equally important is the need to ascertain whether sex is being exchanged for food or whether the person with PWS is being taken advantage of sexually; women with PWS are most at risk for the food-for-sex manipulation. If such sexual exploitation is discovered, a referral to the proper agency for investigation is required. Finally, individuals with PWS can display interpersonal conflict in their relationships. They may have difficulty sharing, meeting the expectations of others, or making empathic connections. Their level of emotional maturity may not be conducive to the level of judgment, commitment, and intimacy necessary in a marriage, even with the help of parents or guardians. Attempts at developing relationships may be further complicated by the poor judgment of some adults with PWS, developing stalking behaviours or erotomania, where a person nurtures a delusional attachment, believing that another is infatuated with them.
When young adults with PWS express a desire to have a baby this idea can be viewed as an early psychological stage of the family romance, such as playing with dolls. This wish can be acknowledged, discussed, and addressed through counselling. It is often managed through substitution, such as having a doll, being involved in the lives of nieces and nephews, being directly supervised in activities with small children, or accepting that not all adults in society have children. When the desire for a baby is complicated by actual menses with the possibility of fertility, it may be difficult for the woman with PWS to accept the use of contraceptives. In these cases, anticipatory guidance requires the involvement of the parent or guardian. Concerns about fertility in PWS raises many medical and ethical issues and appropriate anticipatory guidance, counselling and education is important. Family, religious and social values should play a major part in these discussions.
Pregnancy
Articles and narratives of the four known pregnancies in women with PWS suggest that the gestations and deliveries were uncomplicated. Three babies were delivered by planned caesarean sections. All of the mothers did not breast feed and they were unable to bond with the children. The infants were cared for by others, most often relatives. Common for all was an incapacity to put the needs of the child ahead of their personal needs and desires, especially about food.
The genetics of the children born to mothers with PWS has varied. Theoretically, the chance of a fertile woman with PWS having a non-PWS baby depends on what genetic type of PWS the mother has. A woman with PWS due to uniparental disomy (UPD) is not at risk of passing on a genetically altered chromosome 15 for PWS. A woman with PWS due to a deletion has a 50% chance with each pregnancy of passing on the chromosome with the deletion and having a baby with Angelman syndrome (AS). AS results from deletion or mutation of the maternal chromosome 15 (q11-q13 region), so if the mother passes along her own maternally derived chromosome 15, the baby will be unaffected; but if she passes on her paternally derived chromosome 15 with the deletion instead, then the baby will have AS. Characteristic symptoms of AS are severe developmental delay and/or intellectual disability, little or no speech, movement and balance disorders, and a unique behaviour with an inappropriate happy demeanour that includes frequent laughing, smiling, and excitability. Many have profound sleeping problems and epilepsy. In the four documented cases of pregnancies in women with PWS, two of the children had normal chromosome 15 (mothers had deletion and UPD, respectively), the other two had AS (mothers had both deletion).
In summary:
- Sex hormone replacement can be an important treatment option that should be considered.
- Sex hormone treatment is not advisable for everyone and an individualised approach is important, particularly in regards to dosages that might be lower than standard doses.
- Fertility is not gained by treatment with sex hormones.
- Assessment of fertility/pregnancy for those in sexual relationships is necessary, since infertility cannot be considered as absolute.
- Care should be taken to prevent exploitative relationships, and secure prevention of sexually transmitted diseases.
- Much more knowledge is needed on treatment of hypogonadism, sexuality and fertility in PWS.
Page updated February 2021.
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Paediatric Association of Nigeria - 57th Annual Scientific Conference
IPWSO was proud to support a dedicated PWS symposium at the 57th Annual Scientific Conference of the Paediatric Association of Nigeria (PAN) Conference held 21-23 January 2026 in Ogun State.
Famcare Board Member, Dr Elizabeth Oyenusi, presented on the clinical features, diagnosis, and management of PWS, while Dr Oluwakemi Ashubu shared the first genetically confirmed case of PWS in the country - an important milestone. The session attracted over 104 delegates and sparked a lively discussion.
IPWSO also hosted an exhbition table throughout the 3-day conference, distributing educational materials and engaging directly with healthcare professionals.
We are hugely grateful to Dr Oyenusi, Dr Ashubu and Dr Oladipo (Senior Registrar) for their support in making this educational oureach possible - helping to strengthen awareness and improve early diagnosis of PWS in Nigeria. Funding for this event was kindly provided by Friends of IPWSO (USA).
Global Newborn Society Inaugural Conference, Sweden
The Global Newborn Society’s 1st Conference took place in Uppsala and Stockholm, Sweden, from 2-4 November 2025, marking an exciting milestone for the organisation’s international community.
We were delighted that Dr Susanne Blichfeldt was invited to deliver a plenary lecture on behalf of IPWSO, titled “Neonatal Hypotonia: Clinical Features Seen in PWS That Can Help Differentiate It from Other Congenital Disorders with Similar Symptoms.”
The inaugural event brought together a diverse audience of physicians, nurses, and social care leaders from around the world. The programme was wide-ranging and stimulating, featuring cutting-edge discussions on newborn health, early diagnosis, and innovative care practices - setting a strong foundation for future collaboration within this growing global network.
ASPED 2025, Dubai, UAE
The 6th conference of the Arab Society for Paediatric Endocrinology and Diabetes was held in Dubai over two days on the 26th and 27th September 2025. IPWSO was invited to be a partner and to present at a session on PWS. The conference was attended by over 400 paediatric endocrinologists from more than 20 countries in the Middle East and North Africa. Charlotte Hoybye and Tony Holland attended and presented on behalf of IPWSO and Dr Sarah Ehtisham described her experience seeing patients with PWS in the United Arab Emirates. IPWSO hosted a stand for the whole conference.
In conversation many attendees reported seeing people with PWS and described the challenges they faced, particularly with the management of behaviour problems. Some felt nervous about starting growth hormone as they had had no experience prescribing it to infants with PWS.
Approximately 100 attendees joined the IPWSO mailing list and attendees were very keen to gain knowledge about PWS. Numerous memory sticks with information on PWS and printed material in English and Arabic were taken. Some attendees talked about establishing national or regional PWS Associations.
This was an extremely positive experience and hopefully attending this meeting has laid the groundwork for IPWSO to engage more fully in the Region in the future. We were very well looked after, and the organisers were excellent hosts.
EPNS 2025, Munich, Germany
Together with parents and representatives from the Prader-Willi-Syndrom Vereinigung Deutschland, we were proud to host a PWS exhibition stand at the 16th Congress of the European Paediatric Neurology Society, held in Munich from 8-14 July 2025. The event welcomed over 2,000 medical professionals from around the world.
We had the pleasure of engaging with attendees from Türkiye, Iraq, Palestine, Croatia, Moldova, the Philippines, Ukraine, North Macedonia, Kazakhstan, Armenia, and many local specialists.
Dr. Stefani Didt, Gesellschafter at Katholische Jugendfürsorge der Diözese Augsburg, kindly supported us at the stand and provided expert responses to clinical enquiries. We hope these international connections will contribute to raising awareness about IPWSO’s work, particularly in improving access to genetic testing in underserved regions.
We also highlighted the new treatment for hyperphagia and shared our recent publication, "Improving Mental Health and Well-being for People with PWS."
Sincere thanks to our colleagues from PWS Vereinigung Deutschland and to Dr. Didt for their invaluable support.
ESPE-ESE 2025, Copenhagen, Denmark
IPWSO was honoured to participate in the recent Joint Congress of the European Society for Paediatric Endocrinology (ESPE) and the European Society of Endocrinology (ESE), held in Copenhagen from 10–13 May 2025. This important event provided an invaluable opportunity to raise awareness of Prader-Willi syndrome (PWS) among a broad international medical audience.
IPWSO was represented by our CEO, Margaret Walker, along with Dr Charlotte Höybye from Sweden and Dr. Susanne Blichfeldt from Denmark—both esteemed members of IPWSO’s Clinical and Scientific Advisory Board.
Dr Blichfeldt noted that this congress is a major event in the clinical academic calendar and has a particular significance as it marks the first-ever joint meeting of these two prominent societies. Despite its European designation, the congress attracted participants from around the globe, including delegates from the Middle East, Africa, the United States, Japan, Australia, and New Zealand.
IPWSO’s educational booth was strategically positioned within the Patient Advisory Group area dedicated to rare disease organisations. As part of the programme, we were invited to deliver a 30-minute presentation during the Patient Voices Session. Dr Charlotte Höybye and Dr Susanne Blichfeldt presented on Prader-Willi syndrome (PWS), with a focus on genetics, endocrinology, and clinical manifestations. Our presentation, along with many others, was recorded and is now available on demand via the ESPE-ESE congress platform.
PWS was prominently featured throughout the congress. In a session on the transition of care for patients with rare diseases, Dr. Maithé Tauber (Toulouse, France) discussed the specific challenges associated with the transition period in PWS. She emphasized the need for multidisciplinary care and ongoing specialist follow-up in adulthood through dedicated PWS clinics.
Another session addressed medical and clinical management in both children and adults with PWS, again highlighting the critical importance of a smooth transition from paediatric to adult care and the role of specialised clinics. The session included an in-depth discussion on hyperphagia in PWS, exploring its profound impact on individuals and their families. Management strategies were reviewed, and a new medication, Vykat, was presented as a potential treatment for hyperphagia.
In addition, there was a strong presence of scientific posters on PWS from various countries, covering a wide range of topics such as hormonal therapies, genetic findings, ageing, and guidance for families. A total of 33 posters focused on PWS, reflecting a growing global interest and commitment to advancing knowledge and care in this area.
We were greatly encouraged by the high level of engagement and the visibility given to PWS throughout the congress. This increased awareness brings hope that more children will be diagnosed earlier and receive appropriate, specialised medical care from childhood through to adulthood.
ASPAE 2025, Abidjan, Côte d’Ivoire
After Yaounde (Cameroon 2023) and Alger (Algeria 2024), IPWSO was pleased to be present at the 16th Annual Congress of the African Society of Paediatric and Adolescent Endocrinology (ASPAE), at the invitation of Dr Kouamé Hervé Miconda, Programme Co-organiser. Prior to the main conference, IPWSO, in partnership with Dr Micondo, organised a dedicated PWS workshop which attracted 60 professionals - paediatricians, endocrinologists, doctors, students, nurses, and midwives.
MENA 2025 Abu Dhabi, UAE
The Middle East and North African (MENA) conference for Rare Diseases was held in Abu Dhabi, United Arab Emirates, between 17th and 20th April 2025. Tony Holland represented IPWSO at this meeting and presented a poster about our work. The conference was attended by clinicians, genetic councillors, scientists, and other health disciplines from across North Africa and the Middle East. The conference was in English as many clinicians in this part of the world are from elsewhere and not Arabic speakers. The conference was of a very high standard and ranged broadly across many rare genetically determined conditions as well as there also being discussions about how to develop services and how to seek approval for new treatments. Our poster was one of five that was selected as the best posters exhibited at the meeting. Tony said, "My experience of the conference was very positive and I am sure there are opportunities that can be built on. Being part of the endocrinology meeting, which is likely to be attended by endocrinologists from across the whole region, provides a wonderful opportunity to engage more fully with clinicians most likely to see people with PWS".
Kenya Paediatric Association Annual Scientific Conference, Monbassa, Kenya
Dr Menbere Kahssay and Dr Renson Mukhwana, Aga Khan University Hospital, Nairobi represented the Kenyan team and, together with Drs Constanze Laemmer and Dr Charlotte Höybye, managed the IPWSO educational booth at our first meeting in this region.
A dedicated session on PWS significantly raised awareness and knowledge about the syndrome among paediatricians and allied health professionals.
Dr Kahssay said, "We were able to have track and plenary session and four days interaction with the participants at the booth.
The PWS session focused on case experiences and regional differences in PWS management. Thanks to IPWSO’s support, Drs Charlotte Hoybye and Constanze Lammer joined as expert speakers, sharing their valuable experiences in managing PWS across the neonatal, childhood, and adult stages".
Dr Menbere Kahssay and Dr Renson Mukhwana presented genetically confirmed local cases, highlighting diagnostic challenges and treatment approaches.
Third Biennial Rare Diseases Conference, Rare X, Johannesburg, South Africa
Karin Clarke and Molelekeng Sethuntsa organised the IPWSO exhibition table at this event in Johannesburg from 14-17 February 2024. Molelekeng attended the conference and reported on the excellent discussions that focused on the challenges of early diagnosis, especially in Africa, centres of excellence, and ways that the Department of Health, WHO and RDI can improve detection and treatment of rare diseases.
6th RARE Summit 2023, Cambridge, UK
Tony Holland, President, and Agnes Hoctor, Communications and Membership Manager, represented IPWSO at the 6th RARE Summit organised by Cambridge Rare Disease Network on 12 October, 2023.
MetaECHO® 2023, Global Conference, Albuquerque, New Mexico
The 5th MetaECHO® Global Conference took place from September 18-21 in Albuquerque, New Mexico. It celebrated 20 years of ECHO programmes and brought together ECHO leaders, partner teams, government officials, funders, policy makers, and industry experts to share retrospective work and thoughts on the future of ECHO. Our President, Tony Holland, presented a paper on “A Global ECHO Programme for the Rare Disorder – PWS", based on IPWSO’s Project ECHO programme.
EPNS 2023, Prague, Czech Republic
The 15th European Paediatric Neurology Society Congress (EPNS) took place from 20-24 June. Tünde Liplin, PWS Hungary, and Hana Verichová, PWS Czechia, represented IPWSO. Twenty-two people from countries including Georgia, Israel, Lithuania, Turkey, Italy, Slovakia, Romania, Netherlands, Bosnia Herzegovina, Belgium, Argentina, Norway, Serbia, India, and Australia subscribed to the "Stay in touch with IPWSO!" contact list. Tünde reported that many people came to the stand just to inquire and chat, the majority of whom were hearing about IPWSO and our work for the first time.
ECE 2023, Istanbul, Turkey
The European Congress of Endocrinology (ECE) took place from 13-16 May. We hosted an information table and were represented by IPWSO advisers, Constanze Lämmer and Charlotte Höybye, and also our Communications and Membership Manager, Agnes Hoctor. We were pleased to be given the opportunity to present on IPWSO and PWS at the Hub Session. The most exciting and important element for us was that the Turkish location meant that delegates came from many countries in Middle East as well as Europe.
ASPAE 2023, Yaoundé, Cameroon
We hosted an educational booth and presented at the round table on Obesity at this important Endocrinology conference hosted by the African Society of Paediatric and Adolescent Endocrinology (ASPAE) from 9-10 February. Read our blog about our visit.
ECE 2021, Online
We hosted an educational booth and gave a presentation at the European Congress of Endocrinology in May 2021.
ESPE 2019, Vienna, Austria
We exhibited at the European Society of Paediatric Endocrinology (ESPE) Conference in Vienna, Austria, which took place in September 2019. Find out more in our blog.
ECE 2019, Lyon, France
We exhibited at the European Congress of Endocrinology in May 2019.
Dr Ashubu discussing IPWSO's educational materials with delegates at our booth.
IPWSO was honoured to be invited to present at the Global Newborn Society's Inaugural Conference.
Dr Sarah Ehtisham presenting at ASPED 2025 followed by a panel discussion.
Colleagues from PWS Vereinigung Deutschland help manage our PWS stand at EPNS 2025. Many thanks to all the parents and carers for their invaluable support!
Dr Charlotte Höybye (Sweden) and Dr. Susanne Blichfeldt (Denmark) presenting at the ESPE-ESE Patient Voices Session - May 2025
Dr Blichfeldt and Margaret Walker (CEO) managing our IPWSO educational booth.
François Besnier, IPWSO's Vice President, meeting some of our travel fellowship delegates at ASPAE 2025.
IPWSO's poster achieves top award!
Many thanks to Drs Constanze Laemmer, Menbere Kahssay, Charlotte Höybye and Renson Mukwana for all their support at KPA 2025.