Does assisted reproductive technology cause birth defects?

Assisted reproductive technology and neonatal intensive care unit: A retrospective observational study from a single center

BACKGROUND

An increasing number of infants are being conceived using assisted reproductive technology (ART). The effects of infertility treatments (IFTs) on infant outcomes have been extensively debated; however, a consensus has not yet been reached. In the present study, we investigated the impact of IFTs on neonatal intensive care unit (NICU) managements using data collected at a single large NICU center.

METHODS

We retrospectively investigated patients admitted to the University of Tokyo Hospital NICU during three different time periods (2010, 2015, and 2020). We included 131, 201, and 323 infants, respectively, and compared a number of factors among groups classified by the mode of conception: spontaneous pregnancy (SP), non-ART (conceived with assisted ovulation or artificial insemination), and ART. We also compared the mode of conception among inborn singletons.

RESULTS

The rate of admission of ART infants significantly increased from 2010 (9.1%) to 2015 (22.9%) and 2020 (25.7%) (p values of <0.05 and <0.01, respectively). When compared among inborn singletons, ART infants were more often admitted to NICU (p < 0.01). Congenital anomalies and surgical interventions were significantly more frequent in the SP group than in the ART group (p < 0.01). No significant differences were observed in neonatal outcomes among ART infants from 2010 to 2015/2020.

CONCLUSIONS

The rate of ART infants admitted to the NICU has significantly increased, with ART pregnancies now accounting for 25% of admissions to the perinatal medical center. ART procedure may be a risk factor for NICU admission. Neonatal intensive care is becoming increasingly indispensable for ART pregnancies.

HebbPlot: an intelligent tool for learning and visualizing chromatin mark signatures

BACKGROUND

Histone modifications play important roles in gene regulation, heredity, imprinting, and many human diseases. The histone code is complex and consists of more than 100 marks. Therefore, biologists need computational tools to characterize general signatures representing the distributions of tens of chromatin marks around thousands of regions.

RESULTS

To this end, we developed a software tool, HebbPlot, which utilizes a Hebbian neural network in learning a general chromatin signature from regions with a common function. Hebbian networks can learn the associations between tens of marks and thousands of regions. HebbPlot presents a signature as a digital image, which can be easily interpreted. Moreover, signatures produced by HebbPlot can be compared quantitatively. We validated HebbPlot in six case studies. The results of these case studies are novel or validating results already reported in the literature, indicating the accuracy of HebbPlot. Our results indicate that promoters have a directional chromatin signature; several marks tend to stretch downstream or upstream. H3K4me3 and H3K79me2 have clear directional distributions around active promoters. In addition, the signatures of high- and low-CpG promoters are different; H3K4me3, H3K9ac, and H3K27ac are the most different marks. When we studied the signatures of enhancers active in eight tissues, we observed that these signatures are similar, but not identical. Further, we identified some histone modifications - H3K36me3, H3K79me1, H3K79me2, and H4K8ac - that are associated with coding regions of active genes. Other marks - H4K12ac, H3K14ac, H3K27me3, and H2AK5ac - were found to be weakly associated with coding regions of inactive genes.

CONCLUSIONS

This study resulted in a novel software tool, HebbPlot, for learning and visualizing the chromatin signature of a genetic element. Using HebbPlot, we produced a visual catalog of the signatures of multiple genetic elements in 57 cell types available through the Roadmap Epigenomics Project. Furthermore, we made a progress toward a functional catalog consisting of 22 histone marks. In sum, HebbPlot is applicable to a wide array of studies, facilitating the deciphering of the histone code.

Assisted Reproductive Technology Surveillance - United States, 2014

PROBLEM/CONDITION

Since the first U.S. infant conceived with assisted reproductive technology (ART) was born in 1981, both the use of ART and the number of fertility clinics providing ART services have increased steadily in the United States. ART includes fertility treatments in which eggs or embryos are handled in the laboratory (i.e., in vitro fertilization [IVF] and related procedures). Women who undergo ART procedures are more likely than women who conceive naturally to deliver multiple-birth infants. Multiple births pose substantial risks to both mothers and infants, including obstetric complications, preterm delivery, and low birthweight infants. This report provides state-specific information for the United States (including the District of Columbia and Puerto Rico) on ART procedures performed in 2014 and compares birth outcomes that occurred in 2014 (resulting from ART procedures performed in 2013 and 2014) with outcomes for all infants born in the United States in 2014.

PERIOD COVERED

2014.

DESCRIPTION OF SYSTEM

In 1996, CDC began collecting data on ART procedures performed in fertility clinics in the United States as mandated by the Fertility Clinic Success Rate and Certification Act of 1992 (FCSRCA) (Public Law 102-493). Data are collected through the National ART Surveillance System (NASS), a web-based data collection system developed by CDC. This report includes data from 52 reporting areas (the 50 states, the District of Columbia, and Puerto Rico).

RESULTS

In 2014, a total of 169,568 ART procedures (range: 124 in Wyoming to 21,018 in California) with the intent to transfer at least one embryo were performed in 458 U.S. fertility clinics and reported to CDC. These procedures resulted in 56,028 live-birth deliveries (range: 52 in Wyoming to 7,230 in California) and 68,782 infants born (range: 64 in Wyoming to 8,793 in California). Nationally, the total number of ART procedures performed per million women of reproductive age (15-44 years), a proxy measure of the ART usage rate, was 2,647 (range: 364 in Puerto Rico to 6,726 in Massachusetts). ART use exceeded the national average in 13 reporting areas (Connecticut, Delaware, the District of Columbia, Hawaii, Illinois, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Virginia). Eight reporting areas (Connecticut, the District of Columbia, Hawaii, Illinois, Maryland, Massachusetts, New Jersey, and New York) had rates of ART use exceeding 1.5 times the national average. Nationally, among ART transfer procedures in patients using fresh embryos from their own eggs, the average number of embryos transferred increased with increasing age of the woman (1.7 among women aged <35 years, 1.9 among women aged 35-37 years, and 2.3 among women aged >37 years). Among women aged <35 years, who typically are considered to be good candidates for elective single embryo transfer (eSET) procedures, the national eSET rate was 28.5% (range: 4.3% in Puerto Rico to 67.9% in Delaware). In 2014, ART contributed to 1.6% of all infants born in the United States (range: 0.4% in Puerto Rico to 4.7% in Massachusetts) and 18.3% of all multiple-birth infants (range: 5.5% in Alaska and West Virginia to 37.3% in Hawaii), including 18.0% of all twin infants (range: 5.2% in some states to 36.2% in Hawaii) and 26.4% of all triplets and higher-order infants (range: 0% in some states to 65.2% in Hawaii). Percentages of live births that were multiple-birth deliveries were higher among infants conceived with ART (39.4%; range: 11.5% in Delaware to 55.6% in Puerto Rico) than among all infants born in the total birth population (3.5%; range: 2.2% in Puerto Rico to 4.4% in New Jersey). Approximately 38.0% of ART-conceived infants were twin infants, and 2.0% were triplets and higher-order infants. ART-conceived twins accounted for approximately 95.3% of all ART-conceived infants born in multiple deliveries. Nationally, infants conceived with ART contributed to 5.5% of all low birthweight (<2,500 g) infants (range: 1.2% in West Virginia to 14.2% in Massachusetts). Among ART-conceived infants, 27.8% were low birthweight (range: 10.6% in Delaware to 44.4% in Puerto Rico), compared with 8.0% among all infants (range: 5.9% in Alaska to 11.3% in Mississippi). ART-conceived infants contributed to 4.7% of all preterm (<37 weeks) infants (range: 1.2% in Puerto Rico to 13.4% in Massachusetts). Percentages of preterm births were higher among infants conceived with ART (33.2%; range: 18.9% in the District of Columbia to 45.9% in Puerto Rico) than among all infants born in the total birth population (11.3%; range: 8.5% in California to 16.0% in Mississippi). The percentage of ART-conceived infants who were low birthweight was 8.9% (range: 3.2% in some states to 16.1% in Vermont) among singletons and 55.2% (range: 38.5% in Delaware to 77.8% in Alaska) among twins; the corresponding percentages of low birthweight infants among all infants born were 6.3% for singletons (range: 4.6% in Alaska, North Dakota, and Oregon to 9.5% in Puerto Rico) and 55.2% for twins (range: 46.1% in Alaska to 65.6% in Mississippi). The percentage of ART-conceived infants who were preterm was 13.2% (range: 7.5% in Rhode Island to 23.4% in West Virginia) among singletons and 62.2% (range: 33.3% in some states to 81.4% in Mississippi) among twins; the corresponding percentages of preterm infants among all infants were 9.7% for singletons (range: 1.7% in the District of Columbia to 14.2% in Mississippi) and 56.6% for twins (range: 47.2% in Vermont to 66.9% in Wyoming).

INTERPRETATION

The percentage of infants conceived with ART varied considerably by reporting area. Multiple births from ART contributed to a substantial proportion of all twins, triplets, and higher-order infants born. Low birthweight and preterm infant birth rates were disproportionately higher among ART-conceived infants than among the overall birth population. Although women aged <35 years are typically considered good candidates for eSET, on average two embryos were transferred per ART procedure with women in this group. Compared with ART-conceived singletons, ART-conceived twins were approximately five times more likely to be born preterm and approximately six times more likely to be born with low birthweight. Singleton infants conceived with ART had higher percentages of preterm birth and low birthweight than all singleton infants born in the United States. ART use per population unit was geographically variable, with 13 reporting areas showing ART use higher than the national rate. Of the four states (Illinois, Massachusetts, New Jersey, and Rhode Island) with comprehensive statewide-mandated health insurance coverage for ART procedures (i.e., coverage for at least four cycles of IVF), three (Illinois, Massachusetts, and New Jersey) had rates of ART use exceeding 1.5 times the national rate. This type of mandated insurance has been associated with greater use of ART and likely accounts for some of the difference in per capita ART use observed among states.

PUBLIC HEALTH ACTION

Reducing the number of embryos transferred and increasing use of eSET when clinically appropriate could help reduce multiple births and related adverse health consequences. Because twins account for the majority of ART-conceived multiple births, improved provider practices and patient education and counseling on the maternal and infant health risks of having twins are needed. Although ART contributes to high percentages of multiple births, other factors not investigated in this report (e.g., delayed childbearing and use of non-ART fertility treatments) also contribute to multiple births and warrant further study.

Assisted Reproductive Technology Surveillance - United States, 2013

PROBLEM/CONDITION

Since the first U.S. infant conceived with assisted reproductive technology (ART) was born in 1981, both the use of ART and the number of fertility clinics providing ART services have increased steadily in the United States. ART includes fertility treatments in which eggs or embryos are handled in the laboratory (i.e., in vitro fertilization [IVF] and related procedures). Women who undergo ART procedures are more likely than women who conceive naturally to deliver multiple-birth infants. Multiple births pose substantial risks to both mothers and infants, including obstetric complications, preterm delivery, and low birthweight infants. This report provides state-specific information for the United States (including Puerto Rico) on ART procedures performed in 2013 and compares infant outcomes that occurred in 2013 (resulting from ART procedures performed in 2012 and 2013) with outcomes for all infants born in the United States in 2013.

REPORTING PERIOD COVERED

2013.

DESCRIPTION OF SYSTEM

In 1996, CDC began collecting data on ART procedures performed in fertility clinics in the United States as mandated by the Fertility Clinic Success Rate and Certification Act of 1992 (FCSRCA) (Public Law 102-493). Data are collected through the National ART Surveillance System (NASS), a web-based data collection system developed by CDC. This report includes data from 52 reporting areas (the 50 states, the District of Columbia [DC], and Puerto Rico).

RESULTS

In 2013, a total of 160,521 ART procedures (range: 109 in Wyoming to 20,299 in California) with the intent to transfer at least one embryo were performed in 467 U.S. fertility clinics and were reported to CDC. These procedures resulted in 53,252 live-birth deliveries (range: 47 in Alaska to 6,979 in California) and 66,691 infants (range: 61 in Alaska to 8,649 in California). Nationally, the total number of ART procedures performed per million women of reproductive age (15-44 years), a proxy measure of the ART usage rate, was 2,521 (range: 352 in Puerto Rico to 7,688 in DC). ART use exceeded the national rate in 13 reporting areas (California, Connecticut, Delaware, Hawaii, Illinois, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island, Virginia, and DC). Nationally, among ART transfer procedures in patients using fresh embryos from their own eggs, the average number of embryos transferred increased with increasing age of the woman (1.8 among women aged <35 years, 2.0 among women aged 35-37 years, and 2.5 among women aged >37 years). Among women aged <35 years, who typically are considered to be good candidates for elective single embryo transfer (eSET) procedures, the national eSET rate was 21.4% (range: 4.0% in Idaho to 77.5% in Delaware). In 2013, ART contributed to 1.6% of all infants born in the United States (range: 0.2% in Puerto Rico to 4.8% in Massachusetts) and 18.7% of all multiple-birth infants (range: 4.5% in Puerto Rico to 35.7% in Massachusetts), including 18.5% of all twin infants (range: 4.5% in Mississippi to 35.3% in Massachusetts) and 25.2% of all triplet and higher-order infants (range: 0% in several reporting areas to 51.5% in New Jersey). Multiple-birth deliveries were higher among infants conceived with ART (41.1%; range: 20.4% in Delaware to 61.6% in Wyoming) than among all infants born in the total birth population (only 3.5%; range: 1.8% in Puerto Rico to 4.5% in Massachusetts and New Jersey). Approximately 39% of ART-conceived infants were twin infants, and 2% were triplet and higher-order infants. ART-conceived twins accounted for approximately 95.4% of all ART-conceived infants born in multiple deliveries. Nationally, infants conceived with ART contributed to 5.8% of all low birthweight (<2,500 grams) infants (range: 0.9% in Puerto Rico to 15.1% in Massachusetts). Among ART-conceived infants, 29.1% were low birthweight (range: 18.3% in Delaware to 42.6% in Louisiana), compared with 8.0% among all infants (range: 5.8% in Alaska to 11.5% in Mississippi). ART-conceived infants contributed to 4.6% of all preterm (<37 weeks) infants (range: 0.6% in Puerto Rico to 13.3% in Massachusetts). Preterm birth rates were higher among infants conceived with ART (33.6%; range: 22.3% in DC to 50.7% in Louisiana) than among all infants born in the total birth population (11.4%; range: 8.8% in California to 16.6% in Mississippi). The percentage of ART-conceived infants who were low birthweight was 9.0% (range: 5.1% in Mississippi to 19.7% in Puerto Rico) among singletons and 56.3% (range: 48.3% in Maine to 72.4% in Puerto Rico) among twins; the corresponding percentages among all infants born were 6.3% for singletons (range: 4.6% in Alaska to 9.6% in Mississippi and Puerto Rico) and 55.3% for twins (range: 43.6% in Alaska to 65.6% in Mississippi). The percentage of ART-conceived infants who were preterm varied from 13.3% (range: 8.7% in Rhode Island to 26.9% in West Virginia) among singletons to 61.0% (range: 47.8% in DC to 78.8% in Oklahoma) among twins; the corresponding percentages among all infants were 10.1% for singletons (range: 6.8% in Vermont to 14.8% in Mississippi) and 56.6% for twins (range: 44.7% in New Hampshire to 68.9% in Louisiana).

INTERPRETATION

The percentage of infants conceived with ART varied considerably by reporting area. In most reporting areas, multiple births from ART contributed to a substantial proportion of all twins, triplets, and higher-order infants born, and the low birthweight and preterm infant birth rates were disproportionately higher among ART-conceived infants than among the overall birth population. Although women aged <35 years are typically considered good candidates for eSET, on average two embryos were transferred per ART procedure with women in this group, increasing the overall multiple-birth rates in the United States. Compared with ART-conceived singletons, ART-conceived twins were approximately four-and-a-half times more likely to be born preterm, and approximately six times more likely to be born with low birthweight. Singleton infants conceived with ART had slightly higher rates of preterm delivery and low birthweight than all singleton infants born in the United States. ART use per population unit was geographically variable, with 13 reporting areas showing ART use above the national rate. Of the four states (Illinois, Massachusetts, New Jersey, and Rhode Island) with comprehensive statewide-mandated health insurance coverage for ART procedures (i.e., coverage for at least four cycles of IVF), two states (Massachusetts and New Jersey) had rates of ART use exceeding twice the national level. This type of mandated insurance has been associated with greater use of ART and likely accounts for some of the difference in per capita ART use observed among states.

PUBLIC HEALTH ACTIONS

Reducing the number of embryos transferred per ART procedure and increasing use of eSET, when clinically appropriate (typically for women aged <35 years), could help reduce multiple births, particularly ART-conceived twin infants, and related adverse consequences of ART. Because twins account for the majority of ART-conceived multiple births, improved patient education and counseling on the maternal and infant health risks of having twins is needed. Although ART contributes to high rates of multiple births, other factors not investigated in this report (e.g., delayed childbearing and non-ART fertility treatments) also contribute to multiple births and warrant further study.

Assisted reproduction: Ethical and legal issues

Since inception, the use of assisted reproductive technologies (ART) has been accompanied by ethical, legal, and societal controversies. Guidelines have been developed to address many of these concerns; however, the rapid evolution of ART requires their frequent re-evaluation. We review the literature on ethical and legal aspects of ART, highlighting some of the most visible and challenging topics. Of specific interest are: reporting of ART procedures and outcomes; accessibility to ART procedures; issues related to fertility preservation, preimplantation genetic testing, gamete and embryo donation, and reproductive outcomes after embryo transfer. Improvements in ART reporting are needed nationally and worldwide. Reporting should include outcomes that enable patients to make informed decisions. Improving access to ART and optimizing long-term reproductive outcomes, while taking into account the legal and ethical consequences, are challenges that need to be addressed by the entire community of individuals involved in ART with the assistance of bioethicists, legal counselors, and members of society in general.

Anatomical causes of female infertility and their management

The main female anatomical causes of infertility include post-infectious tubal damage, endometriosis, and congenital/acquired uterine anomalies. Congenital (septate uterus) and acquired (myomas and synechiae) diseases of the uterus may lead to infertility, pregnancy loss, and other obstetric complications. Pelvic inflammatory disease represents the most common cause of tubal damage. Surgery still remains an important option for tubal factor infertility, with results in terms of reproductive outcome that compare favorably with those of in vitro fertilization. Endometriosis is a common gynecologic condition affecting women of reproductive age, which can cause pain and infertility. The cause of infertility associated with endometriosis remains elusive, suggesting a multifactorial mechanism involving immunologic, genetic, and environmental factors. Despite the high prevalence of endometriosis, the exact mechanisms of its pathogenesis are unknown. Specific combinations of medical, surgical, and psychological treatments can ameliorate the quality of life of women with endometriosis. In the majority of cases, surgical treatment of endometriosis has promoted significant increases in fertilization rates. There are obvious associations between endometriosis and the immune system, and future strategies to treat endometriosis might be based on immunologic concepts.

Placental development during early pregnancy in sheep: effects of embryo origin on fetal and placental growth and global methylation

The origin of embryos including those created through assisted reproductive technologies might have profound effects on placental and fetal development, possibly leading to compromised pregnancies associated with poor placental development. To determine the effects of embryo origin on fetal size, and maternal and fetal placental cellular proliferation and global methylation, pregnancies were achieved through natural mating (NAT), or transfer of embryos generated through in vivo (NAT-ET), IVF, or in vitro activation (IVA). On Day 22 of pregnancy, fetuses were measured and placental tissues were collected to immunologically detect Ki67 (a marker of proliferating cells) and 5-methyl cytosine followed by image analysis, and determine mRNA expression for three DNA methyltransferases. Fetal length and labeling index (proportion of proliferating cells) in maternal caruncles (maternal placenta) and fetal membranes (fetal placenta) were less (P < 0.001) in NAT-ET, IVF, and IVA than in NAT. In fetal membranes, expression of 5-methyl cytosine was greater (P < 0.02) in IVF and IVA than in NAT. In maternal caruncles, mRNA expression for DNMT1 was greater (P < 0.01) in IVA compared with the other groups, but DNMT3A expression was less (P < 0.04) in NAT-ET and IVA than in NAT. In fetal membranes, expression of mRNA for DNMT3A was greater (P < 0.01) in IVA compared with the other groups, and was similar in NAT, NAT-ET, and IVF groups. Thus, embryo origin might have specific effects on growth and function of ovine uteroplacental and fetal tissues through regulation of tissue growth, DNA methylation, and likely other mechanisms. These data provide a foundation for determining expression of specific factors regulating placental and fetal tissue growth and function in normal and compromised pregnancies, including those achieved with assisted reproductive technologies.

Analysing the sperm epigenome: roles in early embryogenesis and assisted reproduction

An understanding of the epigenetic mechanisms involved in sperm production and their impact on the differentiating embryo is essential if we are to optimize fertilization and assisted reproduction techniques in the future. Male germ cells are unique in terms of size, robustness, and chromatin structure, which is highly condensed owing to the replacement of most histones by protamines. Analysis of sperm epigenetics requires specific techniques that enable the isolation of high quality chromatin and associated nucleic acids. Histone modification, DNA methylation and noncoding RNAs have important, but so far underestimated, roles in the production of fertile sperm. Aberrations in these epigenetic processes have detrimental consequences for both early embryo development and assisted reproductive technology. Emerging computational techniques are likely to improve our understanding of chromatin dynamics in the future.

Dysmorphic features in 2-year-old IVF/ICSI offspring

BACKGROUND

An increased risk of major congenital abnormalities after IVF and ICSI has been described, but underlying mechanisms are unclear. This study evaluates the effects of ovarian hyperstimulation, the in vitro procedure and time to pregnancy (TTP) - as proxy for the severity of subfertility - on the prevalence of dysmorphic features.

DESIGN/METHODS

Participants were singletons born following controlled ovarian hyperstimulation-IVF/ICSI (COH-IVF/ICSI; n=66), or modified natural cycle-IVF/ICSI (MNC-IVF/ICSI; n=56), or to subfertile couples who conceived naturally (Sub-NC; n=86). Dysmorphic features were assessed according to the method of Merks et al., and are classified into 'minor variants' (minor anomalies or common variants) and 'abnormalities' (clinically relevant or irrelevant abnormalities). We focussed on minor anomalies as they indicate altered embryonic development and because they have the advantage of a higher prevalence.

RESULTS

The prevalences of any of the outcome measures were similar in the three groups. One or more minor anomalies, our primary outcome measure, occurred in 50% of COH-IVF/ICSI, 54% of MNC-IVF/ICSI and 53% of Sub-NC children. TTP in years was significantly associated with abnormalities (adjustedOR=1.20; 95%CI=1.02-1.40), especially with clinically relevant abnormalities (adjustedOR=1.22; 95%CI=1.01-1.48).

CONCLUSIONS

The study indicates that ovarian hyperstimulation and the in vitro procedure are not associated with an increase in dysmorphic features. The positive association between TTP and clinically relevant abnormalities suggests a role of the underlying subfertility and its determinants in the genesis of dysmorphic features.

Long-term complications of assisted reproductive technologies

Since the birth of the first baby through in vitro fertilisation over 30 years ago, there has been a rapid increase in the number of women using assisted reproductive technologies. New techniques are constantly being introduced and are evolving rapidly. Understanding the long-term impact of these treatments, which have been linked with several potential complications affecting the mother and the child, poses a constant challenge for the scientific community. The main complications discussed in this review include the rare but serious risk of thromboembolic disease particularly in the upper half of the body and a higher risk of pregnancy complications including abnormal placentation, miscarriage, gestational diabetes and hypertensive disorders. A link between assisted conception and a number of genital cancers particularly of the breast, ovary and endometrium has also been suggested, but the evidence is currently inconclusive. A number of foetal and neonatal complications including imprinting disorders, low birth weight, congenital malformations and growth disorders are also discussed.

Different distribution of the genetic subtypes of the Prader-Willi syndrome in the elderly

The Prader-Willi syndrome (PWS) is a genetic disorder caused by the absent expression of the paternal copy of maternally imprinted genes in chromosome region 15q11-13. The frequencies of different subtypes in PWS are usually given in literature as 70% deletion, 25-30% maternal uniparental disomy (mUPD) and 3-5% others (imprinting centre (IC) defects and translocations). Little is known about factors that influence the frequency of genetic subtypes in PWS. The study sample comprised 102 adults with clinically and genetically confirmed PWS, contacted through the Dutch Prader-Willi Parent Association and through physicians specialized in treating persons with intellectual disabilities. Genetic testing showed 55 persons (54%) with a paternal deletion, 44 persons (43%) with an mUPD and 3 persons (3%) with a defect of the IC. The observed distribution in our study differed from that in literature (70% deletion, 30% mUPD), which was statistically significant (z-score: P<0.05). This was mainly caused by a higher proportion of mUPD in the advanced age groups. Differences in maternal age and BMI of persons with PWS could not explain the differences in distribution across the age groups. Our study population had a much broader age range, compared with other studies, because of a predominance of elderly people (40+ years) with PWS. In other studies, these elderly persons might have been undiagnosed and/or underreported because of a lack of genetic diagnosis. The results underline both the need for correct genetic diagnosis in all persons with PWS and adjustment of the guidelines for preventive management in adulthood.