Cornel, Martina Cornelia

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As the relative contribution of congenital anomalies to infant mortality and morbidity increases, insight into their etiology becomes more and more important. A decrease of the prevalence of these anomalies is of major importance, as was stated in the WHO programme "Health for all by the year 2000". At present, in about 80% of cases the etiology of congenital anomalies is either multifactorial or unknown (Chapter 1,). When the etiology of an anomaly is ultifactorial, the individual genetic and environmental factors involved are unknown in almost all cases. In 1974 the Committee of Medical and Public Health Research of the European Community (EC) decided to set up a network of registrations of congenital anomalies in EC member states to increase the knowledge of the occurrence of congenital anomalies. This network was called EUROCAT: EUropean Registration Of Congenital Anomalies. In 1974 this network consisted of a total of 24 regionial registrations in 13 countries, covering more than 380,000 births annually, with a central facility for coordination and research in Brussels (Chapter 2.2). ... Zie: Summar

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   University of GroningenResgistration and prevention of congenital anomalies.Cornel, Martina CorneliaIMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:1993Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Cornel, M. C. (1993). Resgistration and prevention of congenital anomalies. s.n.CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 06-06-2022Chapter 7: SUMMARYAs the relative contribution of congenital anomalies to infant mortality andmorbidity increases, insight into their etiology becomes more and more important.A decrease of the prevalence of these anomalies is of major importance, as wasstated in the WHO programme "Health for all by the year 2000". At present, inabout 80Vo of cases the etiologl of congenital anomalies is either multifactorial orunknown (Chapter 1,). When the etiology of an anomaly is multifactorial, theindividual genetic and environmental factors involved are unknown in almost allcases. In 1974 the Committee of Medical and Public Health Research of theEuropean Community (EC) decided to set up a network of registrations ofcongenital anomalies in EC member states to increase the knowledge of theoccurrence of congenital anomalies. This network was called EUROCAT:EUropean Registration Of Congenital Anomalies. In l"99L this network consistedof a total of 24 reg1onial registrations in 13 countries, covering more than 380,000births annually, with a central facility for coordination and research in Brussels(Chapter 2.2).REGISTRATION OF CONGEMTAL ANOMALIESThe first Dutch registration of congenital anomalies started in 1981 in thenorthern Netherlands. In the beginning an important question was whether such aregistration would be feasable in the Netherlands. It turned out that manydoctors, midwives and parents in the northern Netherlands were willing tocollaborate in order to collect data on infants and fetuses with congenitalanomalies (Chapter 2.7). Adequate protection of privacy could be achieved.THE OCCURRENCE OF CONGEMTAL ANOMALIESThe occurrence of congenital aaomalies in one of the EUROCAT-regions, thenorthern Netherlands, is described in chapter 3. The measures of occurrsnce usedare the livebirth prevalence, the total birth prevalence and the prevalence amonglive and stillbirths (Chapter 2.7). A total of 125L children and fetuses born in theperiod 1981-1986 were notified to EUROCAT, which was 2.5Vo of all live andstillbirths covered (Chapter 3.1). In the northern Netherlands the total birthprevalence of neural tube defects (1-.43 per 1000) is lower than in the UnitedKingdom (UK) and Ireland but higher than in other continental Europeanregions. Cleft lip with or without palate (CLP), not combined with othermalformations, also shows a high frequency (1.22 per 1000 births). Thisprevalence has been stable since 1970. The pattern of occurrence of CLP (e.g.se:natio, site of the defect) 15 5imilnr to other regions (Chapter 3.2). Research onthe reasons for the high prevalence is still being carried out.137ETIOLOGY OF CONGENITAL ANOMALIESAfter the epidemic of limb reduction defects caused by thalidomide, it was hopedthat any new epidemic of congenital anomalies would be dstected at an earlierstage. Statistical monitoring techniques developed for this purpose were focussingon the birth prevalence in consecutive periods of time. Monitoring can be moresensitive by investigating combinations of potential risk factors and outcomes(Chapter a.1). Using this new monitoring technique we found an associationbetween ovulation stimulation and fetal neural tube defects (I.{TD) (Chapter 4.2).DECREASING THE LIVEBIRTH PREVALENCE OF CONGEMTALANOMALIESWhen the etiology of a congenital anomaly is known, primary prevention may bepossible. Rubella vaccination to prevent congenital rubella slmdrome is a well-known example. Often the etiology of congenital anomalies is unknown, and theonly way to avoid the livebirth of a child with a serious congenital anomaly is thetermination of a pregnancy (TOP) after prenatal diagnosis of the anomaly.In the Netherlands the prevention and intervention policy for congenitalanomalies is mainly aimed at parents with a known increased risk. However, mostchildren with congenital anomalies are born to parents who were not known tohave an increased risk (Chapter 5.1). Therefore the present policy will not lead toa major further decline of the birth prevalence of congenital anomalies.Chapters 5.2 and 5.3 concern prevention and intervention policies regardingchromosomal anoma-lies, chapter 5.4 concerns neural tube defects.Prenatal cytogenetic diagnosis (PCD) in most EC countries is offered to pregnantwomen of advanced maternal age, to parents who have a history of a previouschild with a chromosomal anomaly, to parents who are carriers of a balancedtranslocation, to mothers who are carriers of an X-linlced disorder and topregnant women in whom a fetal anomaly was detected at ultrasound (Chapter5.2). In some EC countries there are additionai indications. The exact maternalage limit varies from 35 + to 38 + years of age. In the last few years the PCDpolicy has been chansing in some countries, especially in the UK and Switzerland,as individual risk calculation based on maternal serum markers became availableand was improved. Individual risk assessment using maternal serum markers hasthe advantage that the number of Down syndrome cases diagnosed prenatally mayincrease, while the number of invasive procedures, such as amniocentesis (AC)and chorionic villi sampling (CVS), may decrease, even if we take into account anadditional I% of. invasive procedures because of an increased NTD risk. With adecrease of invasive procedures, the number of iatrogenic abortions due to AC orCVS will also decrease.The potential impact of PCD and termination of affected pregnancies in oldermothers has been calculated in chapter 5.3. Data from nine EC countries wasr38used. Of live and stillbirths with serious chromosomal anomalies the percentageborn to mothers older than 35 years of age n 1979-1982 varied from 19 inBelgium to 48 in Ireland. For the uine EC countries collaborating in this study itwas estimated that 297o of children with unbalanced autosomal anomalies wereborn to mothers older than 35 years of age.The total birth prevalence of NTD in Europe showed major regional differences:in the British Isles it varied from 24 to 38 per l-0,000, in continental Europe from10.7 to L4.3 per 10,000 (Chapter 5.4). This last figure represents the northernNetherlands. The impact of prenatal diagnosis and termination of affectedpregnancies varied as well. In Ireland and Malta TOP was not available. In theother countries the percentage of anencephaly cases born at induced abortionvaried from 47.4 in the northern Netherlands to 94.1, in Strasbourg. For spinabifida these figures varied from 2.7 in Northern Ireland to 529 in Glasgow. EarlyTOP was more common in British regions with serum alfa fetoprotein screeningprograms. TOP after 28 weeks of pregnancy was relatively common in France.FUTURE DEVELOPMENTS: DOWN SYNDROMEIt is hard to predict future developments regarding the birth prevalence ofcongenital anomalies. For Down syndrome, the total birth prevalence can bepredicted from the developments in demographic factors (increasing age specificfertility in women aged 29+, increasing number of women aged 35+). Theprevalence of Down syndrome conceptusses will increase as a result ofdemographic changes. Meanwhile the increased use of PCD will lead to adecrease of Down syndrome among livebirths. In chapter 5.6 a model is describedto quanti$ the result of these changes on the Down slndrome prevalence. In theNetherlands, with present indications for PCD and with a utifization ratio of 50Vo,an increase of the livebirth prevalence of Down syndrome from 1.36 per 1000 in1992 to 1.76 per 1000 in 2001 is to be expected. The number of PCDcorresponding to these figures increases from 7,900 'rn t992 to 14,500 in 2001. Thenumber of iatrogenic abortions, caused by amniocentesis/ chorionic villi sampling,would increase from 79 to L45 annually. The model described in chapter 5.6 canbe used to evaluate the consequences of alternative forms of Down syndromescreening.FUTURE DEVELOPMENTS: GENERALContinued research has, in the past decade, led to the identification of factorsassociated with the origin of congenital anomalies (Chapter 6). Some of thesefactors have opened possibilities for primary prevention in the future. Researchmay reveal new risk factors. Strategies that are presently being used in other ECmember states may inspire the Dutch health authorities to review the nationalprevention and intervention policy.t39INFORMATION OF THE PUBLICInformation available to scientists or health workers on the causes of congenitalanomalies and on the possibilities to decrease the risks of congenital anomaliesmay not always reach the couples who plan to get pregnant. Some causes ofcongenital anomalies may not be identified and information on preventive orinterventive options may not be passed on. When parents have a child with aserious congenital anomaly, referral for genetic counseling is a step to optimizethe information on the etiology of their childs anomaly, the recurrence risk andpossibilities for prevention and intervention. We compared the data of thenorthern Netherlands registration of congenital anomalies (years of birth 1981-1986) and data of the genetic clinic (Chapter 5.5). After the birth of the childwith a congenital anomaly, 17Vo of the parental couples had been referred forgenetic counseling. Some of the couples who do not use interventive policies(Chapter 5.2 and 5.3) may not be aware of these possibilities. Continued attentionis ueeded to optimize the availability of information for future parents.140

Resgistration and prevention of congenital anomalies.

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Resgistration and prevention of congenital anomalies.

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