nuchal translucency ( nt ) measurement is an excellent and sensitive screening test for fetal chromosomal abnormalities . it is the sonographic appearance of subcutaneous accumulation of fluid behind the fetal neck in the first trimester of pregnancy . possible causes for the development of this increased fluid - filled space include cardiac failure secondary to structural malformation , abnormalities in the extracellular matrix , and ahnormal or delayed development of the lymphatic system . increased nt which is defined a nt measurement above the 95th centile ( 1 ) is found in 5% of the screened fetuses ( 2 ) , of which the majorities are chromosomally and anatomically normal . the association of increased nt with chromosomal and nonchromosomal abnormalities has been studied for the past two decades ( 27 ) . in addition , the prevalence of chromosomal defects and adverse pregnancy outcome ( apo ) including miscarriage , fetal loss , and fetal abnormalities increases exponentially with nt thickness ( 8) . despite of many studies , there is still uncertainty and concern about the outcome of fetuses with increased nt ; this may cause severe anxiety in parents . in fact there is not a general agreement on how to counsel parents and diminish anxiety about fetal development . in this study we aimed to evaluate the outcome of pregnancies with increased nt in our population in order to use in counseling . this cross sectional study was performed at iranian fetal medicine foundation ( fmf ) between january 2009 and december 2011 after approval by local ethics committee . a computer search was carried out to identify all singleton pregnancies with crown  rump length of 4584 mm and nt of  95th centile . the technique used to measure nt followed the guideline recommended by the uk fetal medicine foundation ( 1 ) . all cases were checked for nasal bone and examination of skull , brain , chest , abdominal wall , stomach , bladder and upper and lower extremities . all examinations were performed transabdominal with a curvilinear 26mhz transducer , aloka -10 ( tokyo - japan).the risk of fetal aneuploidy was calculated by astraia software . all cases with increased nt including those with normal karyotype were recommended follow - up scans at 1820 weeks of gestation and fetal echocardiography at 2024 weeks of gestations . the outcome was asked by telephone interviews with parents or the pediatrician whenever was necessary . the follow up period at the time of telephone interviews normal karyotype was defined based on genetic testing or pediatric examination . the prevalence of adverse pregnancy outcome including miscarriage , hydrops , intrauterine death , fetal abnormalities diagnosed before or after delivery and termination of pregnancy including indicated and maternal request was recorded in this study from 9746 screened pregnant women with mean maternal age of 29.8 years ( range from 15 to 46 ) , 186 cases had nt 95th centile at 1114 weeks of gestation ( fig . there were 37(19.8% ) cases of aneuploidy in the study population , including 29 cases of trisomy 21 , three of trisomy 18 , two of trisomy 13 , three of turner syndrome . the rate of abnormal chromosomal defects was increased with increasing nt thickness ( table 1 ) . there were 3 intra uterine fetal death ( 2 multiple anomaly , 1 unknown ) , 2 hydrops fetalis , 4 spontaneous fetal loss , 17 termination of pregnancy ( top ) for anxiety including 3 with normal karyotype . fetal structural abnormalities were found in 13/149 ( 8.7% ) on follow - up ultrasound examinations antenatally ( 7 cases ) and postnatally ( 6 cases ) . the prevalence of fetal malformations was not proportional to the degree of nt thickness as shown in table 2 . therefore 110 ( 77.8% ) children with nt95th centile , normal serial scans , and normal echocardiography were born alive and were reported normal at birth and postnatal follow up ( table 3 ) . approximately 20% of screened women in our study had abnormal karyotype that is in agreement with kagan et al . ( 9 ) that used cut off 95th centile , but disagree with bilardo et al . ( 10 ) who reported 33.8% abnormal karyotype with the same cut off . in a study the prevalence of abnormal karyotype was 44% ( 11 ) which was much higher than our study , this can be explained by considering different cut off for nt measurement by them . after exclusion of adverse pregnancy outcome , the chance of having a normal baby was 95% , this figure can be used in counseling of parents with increased nt in the future . structural anomalies were detected in 8.7% of fetuses which is in agreement with another study ( 12 ) who reported 7.3% and bilardo et al . ( 11 ) the prevalence of fetal malformations was 26% , much higher than our rate , this maybe for including nt above 4 mm as cut off . the prevalence of fetal malformations was not proportional to the degree of nt thickness as shown in table 3 , this can be explained with higher rate of top based on maternal request in group with nt3.5 , but the overall rate of apo was proportional to the degree of nt enlargement . termination of pregnancy was done by 11.4% parents after first trimester screening due to anxiety and uncertainty of future outcome . these parents had rushed decision on top despite of 3 with normal karyotype ; it seems limitation of termination of pregnancy to the age of less than 18 weeks in our country helps this decision . besides , our defensive and cautiously counseling has exacerbated parental anxiety as ville ( 14 ) clearly described the challenging of counseling in cases with increased nt . fortunately a recent review of article reported the rate of neurodevelopmental delay as 1% that is not much different from general population ( 15 ) . our study was not designed for this issue but according to parent s declaration and follow 23 years by the pediatricians , neurodevelopmental delay was not reported . the most common fetal malformation was heart defects that are in keeping with the other studies ( 5 , 1619 ) . the prevalence of cardiac defects was 6 times higher in fetuses with nt above 99th centile in some studies ( 1921 ) , but our small sample size does not let us to draw any conclusion about heart defects . the spontaneous fetal loss rate of 4.6% in the fetuses with increased nt was in correspondence to bilardo et al . our study showed that one out of four fetuses with enlarged nt had an adverse pregnancy outcome according to our definition for apo . uncertainty and rushed decision on top falsely raised the rate of apo , as after exclusion of those with adverse outcome , the chance of having a normal outcome was found to be 95% , that is good information and new hope for counseling in the future . however , larger prospective studies with long - term follow -up and focus on neurodevelopmental delay with standard definition and standardized tools for delay are needed . ethical issues ( including plagiarism , informed consent , misconduct , data fabrication and/or falsification , double publication and/or submission , redundancy , etc ) have been completely observed by the authors .
backgroundto study the outcome of cases with nuchal translucency ( nt )  95th centile in the first trimester of pregnancy.methods:this cross sectional study was performed at iranian fetal medicine foundation ( fmf ) between january 2009 and december 2011 . 
 totally , 186 cases with nt 95th centile who attended for the first trimester screening were studied . 
 all cases with increased nt including those with normal karyotype were followed up with anomaly scan at 1822 weeks and fetal echocardiography at 2224 weeks . 
 pregnancy outcome was extracted from delivery records and pediatrics notes and telephone interviews.results:of screened cases , 186 fetuses had an nt95th centile , of them 19.8% were abnormal karyotype , including 29 cases of trisomy 21 , three of trisomy 18 , two of trisomy 13 , three of turner syndrome . 
 77.8% did not show any abnormalities on follow - up examinations . 
 4.6% of cases were found to have malformation antenatally and 4% cases postnatally . 
 11.4% women elected termination of pregnancy without further follow up . 
 there were 4.6% fetal loss and 1.3% hydrops fetalis.conclusion:in this unselected population , the study showed one out of four fetuses with enlarged nt had an adverse pregnancy outcome ( miscarriage , fetal loss , and fetal abnormalities ) , however the chance of having a normal child after exclusion of chromosomal abnormalities and adverse pregnancy outcome was 95% .