Browsing by Author "Klungsoyr, Kari"
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- Epidemiology of congenital cerebral anomalies in Europe: a multicentre, population-based EUROCAT studyPublication . Morris, Joan K.; Wellesley, Diana G.; Barisic, Ingeborg; Addor, Marie-Claude; Bergman, Jorieke E.H.; Braz, Paula; Cavero-Carbonell, Clara; Draper, Elizabeth S.; Gatt, Miriam; Haeusler, Martin; Klungsoyr, Kari; Kurinczuk, Jennifer J.; Lelong, Natalie; Luyt, Karen; Lynch, Catherine; O’Mahony, Mary T.; Mokoroa, Olatz; Nelen, Vera; Neville, Amanda J.; Pierini, Anna; Randrianaivo, Hanitra; Rankin, Judith; Rissmann, Anke; Rouget, Florence; Schaub, Bruno; Tucker, David F.; Verellen-Dumoulin, Christine; Wiesel, Awi; Zymak-Zakutnia, Natalia; Lanzoni, Monica; Garne, EsterObjectives: To describe the epidemiology and geographical differences in prevalence of congenital cerebral anomalies in Europe. Design and setting: Congenital cerebral anomalies (International Classification of Diseases, 10th Revision code Q04) recorded in 29 population-based EUROCAT registries conducting surveillance of 1.7 million births per annum (29% of all European births). Participants: All birth outcomes (live births, fetal deaths from 20 weeks gestation and terminations of pregnancy after prenatal diagnosis of a fetal anomaly (TOPFA)) from 2005 to 2014. Main outcome measures: Prevalence, proportion of associated non-cerebral anomalies, prenatal detection rate. Results: 4927 cases with congenital cerebral anomalies were identified; a prevalence (adjusted for under-reporting) of 9.8 (95% CI: 8.5 to 11.2) per 10 000 births. There was a sixfold difference in prevalence across the registries. Registries with higher proportions of prenatal diagnoses had higher prevalence. Overall, 55% of all cases were liveborn, 3% were fetal deaths and 41% resulted in TOPFA. Forty-eight per cent of all cases were an isolated cerebral anomaly, 25% had associated non-cerebral anomalies and 27% were chromosomal or part of a syndrome (genetic or teratogenic). The prevalence excluding genetic or chromosomal conditions increased by 2.4% per annum (95% CI: 1.3% to 3.5%), with the increases occurring only for congenital malformations of the corpus callosum (3.0% per annum) and 'other reduction deformities of the brain' (2.8% per annum). Conclusions: Only half of the cases were isolated cerebral anomalies. Improved prenatal and postnatal diagnosis may account for the increase in prevalence of congenital cerebral anomalies from 2005 to 2014. However, major differences in prevalence remain between regions.
- Epidemiology of septo-optic dysplasia with focus on prevalence and maternal age – a EUROCAT studyPublication . Garne, Ester; Rissmann, Anke; Addor, Marie-Claude; Barisic, Ingeborg; Bergman, Jorieke; Braz, Paula; Cavero-Carbonell, Clara; Draper, Elisabeth; Gatt, Miriam; Haeusler, Martin; Klungsoyr, Kari; Kurinczuk, Jennifer; Lelong, Nathalie; Luyt, Karen; Lynch, Babak; O’Mahony, Mary; Mokoroaq, Olatz; Nelenr, Vera; Nevilles, Amanda J.; Pierinit, Anna; Randrianaivou, Hanitra; Rankinv, Judith; Rougetw, Florence; Schaubx, Bruno; Tuckery, David; Verellen-Dumoulinz, Christine; Wellesleyaa, Diana; Wieselab, Awi; Zymak-Zakutniaac, Nataliia; Lanzoniad, Monica,; Morrisae, Joan K.Septo-optic nerve dysplasia is a rare congenital anomaly with optic nerve hypoplasia, pituitary hormone deficiencies and midline developmental defects of the brain. The clinical findings are visual impairment, hypopituitarism and developmental delays. The aim of this study was to report prevalence, associated anomalies, maternal age and other epidemiological factors from a large European population based network of congenital anomaly registries (EUROCAT). Data from 29 full member registries for the years 2005-2014 were included, covering 6.4 million births. There were 99 cases with a diagnosis of septo-optic dysplasia. The prevalence of septo-optic dysplasia in Europe was calculated to lie between 1.9 and 2.5 per 100,000 births after adjusting for potential under-reporting in some registries. The prevalence was highest in babies of mothers aged 20-24 years of age and was significantly higher in UK registries compared with other EUROCAT registries (P = 0.021 in the multilevel model) and the additional risk for younger mothers was significantly greater in the UK compared to the rest of Europe (P = 0.027). The majority of septo-optic dysplasia cases were classified as an isolated cerebral anomaly (N = 76, 77%). Forty percent of diagnoses occurred in fetuses with a prenatal diagnosis. The anomaly may not be visible at birth, which is reflected in that 57% of the postnatal diagnoses occurred over 1 month after birth. This is the first population based study to describe the prevalence of septo-optic dysplasia in Europe. Septo-optic dysplasia shares epidemiological patterns with gastroschisis and this strengthens the hypothesis of vascular disruption being an aetiological factor for septo-optic dysplasia.
- Ethics and legal requirements for data linkage in 14 European countries for children with congenital anomaliesPublication . Claridge, Hugh; Tan, Joachim; Loane, Maria; Garne, Ester; Barisic, Ingeborg; Cavero-Carbonell, Clara; Matias Dias, Carlos; Gatt, Miriam; Jordan, Susan; Khoshnood, Babak; Kiuru-Kuhlefelt, Sonja; Klungsoyr, Kari; Mokoroa Carollo, Olatz; Nelen, Vera; Neville, Amanda J.; Pierini, Anna; Randrianaivo, Hanitra; Rissmann, Anke; Tucker, David; de Walle, Hermien; Wertelecki, Wladimir; Morris, Joan K.Introduction: Linking healthcare data sets can create valuable resources for research, particularly when investigating rare exposures or outcomes. However, across Europe, the permissions processes required to access data can be complex. This paper documents the processes required by the EUROlinkCAT study investigators to research the health and survival of children with congenital anomalies in Europe. Methods: Eighteen congenital anomaly registries in 14 countries provided information on all the permissions required to perform surveillance of congenital anomalies and to link their data on live births with available vital statistics and healthcare databases for research. Small number restrictions imposed by data providers were also documented. Results: The permissions requirements varied substantially, with certain registries able to conduct congenital anomaly surveillance as part of national or regional healthcare provision, while others were required to obtain ethics approvals or informed consent. Data linkage and analysis for research purposes added additional layers of complexity for registries, with some required to obtain several permissions, including ethics approvals to link the data. Restrictions relating to small numbers often resulted in a registry's data on specific congenital anomalies being unusable. Conclusion: The permissions required to obtain and link data on children with congenital anomalies varied greatly across Europe. The variation and complexity present a significant obstacle to the use of such data, especially in large data linkage projects. Furthermore, small number restrictions severely limited the research that could be performed for children with specific rare congenital anomalies.
- Long term trends in prevalence of neural tube defects in Europe: population based studyPublication . Khoshnood, Babak; Loane, Maria; Walle, Hermien de; Arriola, Larraitz; Addor, Marie-Claude; Barisic, Ingeborg; Beres, Judit; Bianchi, Fabrizio; Dias, Carlos Matias; Draper, Elizabeth; Garne, Ester; Gatt, Miriam; Haeusler, Martin; Klungsoyr, Kari; Latos-Bielenska, Anna; Lynch, Catherine; McDonnell, Bob; Nelen, Vera; Neville, Amanda J.; O’Mahony, Mary T.; Queisser-Luft, Annette; Rankin, Judith; Rissmann, Anke; Ritvanen, Annukka; Rounding, Catherine; Sipek, Antonin; Tucker, David; Verellen-Dumoulin, Christine; Wellesley, Diana; Dolk, HelenStudy question: What are the long term trends in the total (live births, fetal deaths, and terminations of pregnancy for fetal anomaly) and live birth prevalence of neural tube defects (NTD) in Europe, where many countries have issued recommendations for folic acid supplementation but a policy for mandatory folic acid fortification of food does not exist? Methods: This was a population based, observational study using data on 11 353 cases of NTD not associated with chromosomal anomalies, including 4162 cases of anencephaly and 5776 cases of spina bifida from 28 EUROCAT (European Surveillance of Congenital Anomalies) registries covering approximately 12.5 million births in 19 countries between 1991 and 2011. The main outcome measures were total and live birth prevalence of NTD, as well as anencephaly and spina bifida, with time trends analysed using random effects Poisson regression models to account for heterogeneities across registries and splines to model non-linear time trends. Summary answer and limitations: Overall, the pooled total prevalence of NTD during the study period was 9.1 per 10 000 births. Prevalence of NTD fluctuated slightly but without an obvious downward trend, with the final estimate of the pooled total prevalence of NTD in 2011 similar to that in 1991. Estimates from Poisson models that took registry heterogeneities into account showed an annual increase of 4% (prevalence ratio 1.04, 95% confidence interval 1.01 to 1.07) in 1995-99 and a decrease of 3% per year in 1999-2003 (0.97, 0.95 to 0.99), with stable rates thereafter. The trend patterns for anencephaly and spina bifida were similar, but neither anomaly decreased substantially over time. The live birth prevalence of NTD generally decreased, especially for anencephaly. Registration problems or other data artefacts cannot be excluded as a partial explanation of the observed trends (or lack thereof) in the prevalence of NTD. What this study adds: In the absence of mandatory fortification, the prevalence of NTD has not decreased in Europe despite longstanding recommendations aimed at promoting peri-conceptional folic acid supplementation and existence of voluntary folic acid fortification.
- Maternal age and the prevalence of congenital heart defects in Europe, 1995–2015: A register‐based studyPublication . Mamasoula, Chrysovalanto; Bigirumurame, Theophile; Chadwick, Thomas; Addor, Marie‐Claude; Cavero‐Carbonell, Clara; Matias Dias, Carlos; Echevarría‐González‐de‐Garibay, Luis‐Javier; Gatt, Miriam; Khoshnood, Babak; Klungsoyr, Kari; Randall, Kay; Stoianova, Sylvia; Haeusler, Martin; Nelen, Vera; Neville, Amanda J.; Perthus, Isabelle; Pierini, Anna; Bertaut‐Nativel, Bénédicte; Rissmann, Anke; Rouget, Florence; Schaub, Bruno; Tucker, David; Wellesley, Diana; Zymak‐Zakutnia, Natalya; Barisic, Ingeborg; de Walle, Hermien E.K.; Lanzoni, Monica; Sayers, Gerardine; Mullaney, Carmel; Pennington, Lindsay; Rankin, JudithBackground: Evidence on the direction and strength of association between maternal age and the prevalence of congenital heart defects (CHD) in different age group categories is conflicting. Some studies have illustrated different trends with an increase in prevalence in younger and older age groups while other studies have reported a linear relationship. Given the increase in maternal age over recent years, it is important to study the CHD prevalence by maternal age. Objectives: To examine the association between maternal age and the prevalence of CHD in Europe between 1995 and 2015 using population-based data from 24 registries belonging to the European Surveillance of Congenital Anomalies (EUROCAT) network. Methods: Associations over time of all nonsyndromic CHD according to maternal age category and for three CHD severity groupings (severity group I: very severe; severity group II: severe; severity group III: less severe) were examined using Bayesian multilevel Poisson regression modeling. Further subgroup analyses were undertaken within four maternal age-bands: ≤24, 25–29, 30–34 and 35–44 years. Descriptive summaries are also presented. Results: There were 51,608 nonsyndromic CHD cases in Europe over the 20-year study period. Total prevalence for all CHD combined was increased for younger mothers (≤24 years) and for mothers 35–44 years of age when compared with mothers aged 25–29 years (reference group) (IRR: 1.05, 95% CI: 1.02, 1.07). The total prevalence was increased for severity group I (very severe) only for younger mothers compared to those aged 25–29 years (IRR: 1.14, 95% CI: 1.04, 1.23). We found an increased prevalence of the following CHD subtypes: double outlet right ventricle (IRR:1.33, 95% CI: 1.09, 1.60), hypoplastic left heart syndrome (IRR: 1.18, 95% CI: 1.05, 1.32), hypoplastic right heart syndrome (IRR: 1.41, 95% CI: 1.05, 1.84), atrioventricular septal defect (IRR: 1.15, 95% CI: 1.01, 1.32), coarctation of aorta (IRR: 1.15, 95% CI: 1.03, 1.28) and atrial septal defect (IRR: 1.08, 95% CI: 1.02, 1.13). For older mothers (35–44 years) compared to the reference category, we observed an increased risk in the prevalence for severity group II (IRR: 1.09, 95% CI: 1.03, 1.14), severity group III (IRR: 1.05, 95% CI: 1.01, 1.08) and an increased prevalence of the CHD subtypes: Pulmonary valve stenosis (IRR: 1.22, 95% CI: 1.09, 1.34), ASD (IRR: 1.07, 95% CI: 1.02, 1.13), CoA (IRR: 1.18, 95% CI: 1.06, 1.32) and Tetralogy of Fallot (IRR: 1.14, 95% CI: 1.01, 1.28). Finally, for all age categories compared to the reference category, different associations of ASD and an increased prevalence of CoA was also observed. Conclusions: Based on data for cases of CHD from 24 European populationbased registries, evidence of a positive association between maternal age and the total prevalence of CHD for younger (≤24 years old) and older (35–44 years old) mothers was observed. The results suggest that young maternal age (≤24 years old) is a factor associated with severe CHD phenotypes while a positive association between advanced maternal age (35–44 years old) and mild CHD phenotypes was observed.
- Maternal risk factors for the VACTERL association: a EUROCAT case-control studyPublication . van de Putte, Romy; van Rooij, Iris A.L.M.; Haanappel, Cynthia P.; Marcelis, Carlo L.M.; Brunner, Han G.; Addor, Marie‐Claude; Cavero‐Carbonell, Clara; Matias Dias, Carlos; Draper, Elizabeth S.; Etxebarriarteun, Larraitz; Gatt, Miriam; Khoshnood, Babak; Kinsner‐Ovaskainen, Agnieszka; Klungsoyr, Kari; Kurinczuk, Jenny J.; Latos‐Bielenska, Anna; Luyt, Karen; O'Mahony, Mary T.; Miller, Nicola; Mullaney, Carmel; Nelen, Vera; Neville, Amanda J.; Perthus, Isabelle; Pierini, Anna; Randrianaivo, Hanitra; Rankin, Judith; Rissmann, Anke; Rouget, Florence; Schaub, Bruno; Tucker, David; Wellesley, Diana; Wiesel, Awi; Zymak‐Zakutnia, Natalya; Loane, Maria; Barisic, Ingeborg; Walle, Hermien E.K.; Bergman, Jorieke E.H.; Roeleveld, NelBackground: The VACTERL association (VACTERL) is the nonrandom occurrence of at least three of these congenital anomalies: vertebral, anal, cardiac, tracheoesophageal, renal, and limb anomalies. Despite suggestions for involvement of several genes and nongenetic risk factors from small studies, the etiology of VACTERL remains largely unknown. Objective: To identify maternal risk factors for VACTERL in offspring in a large European study. Methods: A case-control study was performed using data from 28 EUROCAT registries over the period 1997-2015 with case and control ascertainment through hospital records, birth and death certificates, questionnaires, and/or postmortem examinations. Cases were diagnosed with VACTERL, while controls had a genetic syndrome and/or chromosomal abnormality. Data collected included type of birth defect and maternal characteristics, such as age, use of assisted reproductive techniques (ART), and chronic illnesses. Multivariable logistic regression analyses were performed to estimate confounder adjusted odds ratios (aOR) with 95% confidence intervals (95% CI). Results: The study population consisted of 329 VACTERL cases and 49,724 controls with recognized syndromes or chromosomal abnormality. For couples who conceived through ART, we found an increased risk of VACTERL (aOR 2.3 [95% CI 1.3, 3.9]) in offspring. Pregestational diabetes (aOR 3.1 [95% CI 1.1, 8.6]) and chronic lower obstructive pulmonary diseases (aOR 3.9 [95% CI 2.2, 6.7]) also increased the risk of having a child with VACTERL. Twin pregnancies were not associated with VACTERL (aOR 0.6 [95% CI 0.3, 1.4]). Conclusion: We identified several maternal risk factors for VACTERL in offspring befitting a multifactorial etiology.
- Meckel–Gruber Syndrome: a population-based study on prevalence, prenatal diagnosis, clinical features, and survival in EuropePublication . Barisc, Ingeborg; Boban, Ljubica; Loane, Maria; Garne, Ester; Wellesley, Diana; Calzolari, Elisa; Dolk, Helen; Addor, Marie-Claude; Bergman, Jorieke E.H.; Braz, Paula; Draper, Elizabeth S.; Haeusler, Martin; Khoshnood, Babak; Klungsoyr, Kari; Pierini, Anna; Queisser-Luft, Annette; Rankin, Judith; Rissmann, Anke; Verellen-Dumoulin, ChristineMeckel–Gruber Syndrome is a rare autosomal recessive lethal ciliopathy characterized by the triad of cystic renal dysplasia,occipital encephalocele and postaxial polydactyly. We present the largest population-based epidemiological study to date using data provided by the European Surveillance of Congenital Anomalies (EUROCAT) network. The study population consisted of 191 cases of MKS identified between January 1990 and December 2011 in 34 European registries. The mean prevalence was 2.6 per 100 000 births in a subset of registries with good ascertainment. The prevalence was stable over time, but regional differences were observed. There were 145 (75.9%) terminations of pregnancy after prenatal diagnosis, 13 (6.8%) fetal deaths, 33 (17.3%) live births. In addition to cystic kidneys (97.7%), encephalocele (83.8%) and polydactyly(87.3%), frequent features include other central nervous system anomalies (51.4%), fibrotic/cystic changes of the liver (65.5%) of cases with post mortem examination) and orofacial clefts (31.8%). Various other anomalies were present in 64 (37%) patients. As nowadays most patients are detected very early in pregnancy when liver or kidney changes may not yet be developed or may be difficult to assess, none of the anomalies should be considered obligatory for the diagnosis. Most cases (90.2%) are diagnosed prenatally at 14.3±2.6 (range 11–36) gestational weeks and pregnancies are mainly terminated, reducing the number of LB to one-fifth of the total prevalence rate. Early diagnosis is important for timely counseling of affected couples regarding the option of pregnancy termination and prenatal genetic testing in future pregnancies.
- Methadone, Pierre Robin sequence and other congenital anomalies: case-control studyPublication . Cleary, Brian; Loane, Maria; Addor, Marie-Claude; Barisic, Ingeborg; de Walle, Hermien E.K.; Matias Dias, Carlos; Gatt, Miriam; Klungsoyr, Kari; McDonnell, Bob; Neville, Amanda; Pierini, Anna; Rissmann, Anke; Tucker, David F.; Zurriaga, Oscar; Dolk, HelenObjective: Methadone is a vital treatment for women with opioid use disorder in pregnancy. Previous reports suggested an association between methadone exposure and Pierre Robin sequence (PRS), a rare craniofacial anomaly. We assessed the association between gestational methadone exposure and PRS. Design/setting: This case-malformed control study used European Surveillance of Congenital Anomalies population-based registries in Ireland, the Netherlands, Italy, Switzerland, Croatia, Malta, Portugal, Germany, Wales, Norway and Spain, 1995-2011. Patients: Cases included PRS based on International Classification of Disease (ICD), Ninth Edition-British Paediatric Association (BPA) code 75 603 or ICD, Tenth Edition-BPA code Q8708. Malformed controls were all non-PRS anomalies, excluding genetic conditions, among live births, fetal deaths from 20 weeks' gestation and terminations of pregnancy for fetal anomalies. An exploratory analysis assessed the association between methadone exposure and other congenital anomalies (CAs) excluding PRS. Methadone exposure was ascertained from medical records and maternal interview. Results: Among 87 979 CA registrations, there were 127 methadone-exposed pregnancies and 336 PRS cases. There was an association between methadone exposure and PRS (OR adjusted for registry 12.3, 95% CI 5.7 to 26.8). In absolute terms, this association reflects a risk increase from approximately 1-12 cases per 10 000 births. A raised OR was found for cleft palate (adjusted OR 5.0, 95% CI 2.7 to 9.2). Conclusions: These findings suggest that gestational methadone exposure is associated with PRS. The association may be explained by unmeasured confounding factors. The small increased risk of PRS in itself does not alter the risk-benefit balance for gestational methadone use. The association with cleft palate, a more common CA, should be assessed with independent data.
- Prevalence of congenital heart defects in Europe, 2008-2015: A registry‐based studyPublication . Mamasoula, Chrysovalanto; Addor, Marie‐Claude; Carbonell, Clara Cavero; Matias Dias, Carlos; Echevarría‐González‐de‐Garibay, Luis‐Javier; Gatt, Miriam; Khoshnood, Babak; Klungsoyr, Kari; Randall, Kay; Stoianova, Sylvia; Haeusler, Martin; Nelen, Vera; Neville, Amanda J.; Perthus, Isabelle; Pierini, Anna; Bertaut‐Nativel, Bénédicte; Rissmann, Anke; Rouget, Florence; Schaub, Bruno; Tucker, David; Wellesley, Diana; Zymak‐Zakutnia, Natalya; Barisic, Ingeborg; de Walle, Hermien E.K.; Lanzoni, Monica; Mullaney, Carmel; Pennington, Lindsay; Rankin, JudithBackground: The total prevalence of congenital heart defects (CHDs) varies by populations and over time. Studies that examine trends in the prevalence of CHD in different regions may shed light on our understanding of the occurrence of CHD and the impact of different risk factors. Objectives: To examine trends in total and live birth prevalence of nonsyndromic CHD in Europe between the years 2008 and 2015 and to investigate if the decreasing trend reported by previous studies is continuing. Methods: Cases of CHD delivered between January 1, 2008 and December 31, 2015 notified to 25 population-based EUROCAT (European Surveillance of Congenital Anomalies) registries in 14 countries, formed the population-based case-series. Prevalence (total/live) rates and 95% confidence intervals were calculated as the number of cases per 10,000 births (live and stillbirths). Time trends in prevalence of all nonsyndromic CHDs and for three CHD severity groups (very severe, severe, and less severe) were plotted using a Poisson regression multilevel approach. Results: The total prevalence of nonsyndromic CHD was 57.1 per 10,000 births (live births and stillbirths) for the 8-year period and remained stable across the three CHD severity groups while the live birth prevalence was 60.2 per 10,000 births. There was considerable variation in the reported total CHD prevalence and the direction of trends by registry. A decreasing prevalence ofCHD was observed for the Norway and England/Wales registries, whereas the CHD prevalence increased for registries in Italy and Croatia. Conclusions: The total prevalence of CHD in Europe between the years 2008 and 2015 remained stable for all CHD and across the three CHD severity groups. The decreasing trend reported by previous studies has not continued. However, we found significant differences in the total and live birth prevalence by registry.
- Prevalence of microcephaly in Europe: population based studyPublication . Morris, Joan K.; Rankin, Judith; Garne, Ester; Loane, Maria; Greenlees, Ruth; Addor, Marie-Claude; Arriola, Larraitz; Barisic, Ingeborg; Bergman, Jorieke E.H.; Csaky-Szunyogh, Melinda; Dias, Carlos Matias; Draper, Elizabeth S.; Gatt, Miriam; Khoshnood, Babak; Klungsoyr, Kari; Kurinczuk, Jennifer J.; Lynch, Catherine; McDonnell, Robert; Nelen, Vera; Neville, Amanda J.; O'Mahony, Mary T.; Pierini, Anna; Randrianaivo, Hanitra; Rissmann, Anke; Tucker, David; Verellen-Dumoulin, Christine; de Walle, Hermien E.K.; Wellesley, Diana; Wiesel, Awi; Dolk, HelenObjectives: To provide contemporary estimates of the prevalence of microcephaly in Europe, determine if the diagnosis of microcephaly is consistent across Europe, and evaluate whether changes in prevalence would be detected using the current European surveillance performed by EUROCAT (the European Surveillance of Congenital Anomalies). Design: Questionnaire and population based observational study. Setting: 24 EUROCAT registries covering 570 000 births annually in 15 countries. Participants: Cases of microcephaly not associated with a genetic condition among live births, fetal deaths from 20 weeks’ gestation, and terminations of pregnancy for fetal anomaly at any gestation. Main: outcome measures Prevalence of microcephaly (1 Jan 2003-31 Dec 2012) analysed with random effects Poisson regression models to account for heterogeneity across registries. Results: 16 registries responded to the questionnaire, of which 44% (7/16) used the EUROCAT definition of microcephaly (a reduction in the size of the brain with a skull circumference more than 3 SD below the mean for sex, age, and ethnic origin), 19% (3/16) used a 2 SD cut off, 31% (5/16) were reliant on the criteria used by individual clinicians, and one changed criteria between 2003 and 2012. Prevalence of microcephaly in Europe was 1.53 (95% confidence interval 1.16 to 1.96) per 10 000 births, with registries varying from 0.4 (0.2 to 0.7) to 4.3 (3.6 to 5.0) per 10 000 (χ2=338, df=23, I2=93%). Registries with a 3 SD cut off reported a prevalence of 1.74 per 10 000 (0.86 to 2.93) compared with those with the less stringent 2 SD cut off of 1.21 per 10 000 (0.21 to 2.93). The prevalence of microcephaly would need to increase in one year by over 35% in Europe or by over 300% in a single registry to reach statistical significance (P<0.01). Conclusions: EUROCAT could detect increases in the prevalence of microcephaly from the Zika virus of a similar magnitude to those observed in Brazil. Because of the rarity of microcephaly and discrepant diagnostic criteria, however, the smaller increases expected in Europe would probably not be detected. Clear diagnostic criteria for microcephaly must be adopted across Europe.