The Impact of Isolated Increased Nuchal Translucency=95th Centile on Perinatal Outcome: A Prospective Cohort Study from a North Indian Genetic Center

Objectives The aim of this study was to determine the chromosomal abnormalities and other adverse outcomes like miscarriages, intrauterine deaths, structural defects, and genetic syndromes in fetuses with increased nuchal translucency (NT) more than or equal to 95th centile. This study also compared the outcomes in fetuses with NT between 95th and 99th centile and more than 99th centile.Study Design A prospective cohort of 182 patients with isolated increased NT was evaluated by invasive testing. Fetal chromosomes were examined by fluorescent in situ hybridization and karyotype or chromosomal microarray. Euploid pregnancies were followed-up with level II ultrasound and fetal echocardiography. For pregnancies progressing to delivery, the neonates were followed-up till the age of 3 months. Final outcome was reported as normal or abnormal. Collated data for perinatal outcomes was analyzed and compared between fetuses with NT 95th and 99th centile (group I) and NT more than 99th centile (group II).Results Of the 202 patients recruited, 182 patients consented for invasive testing and chromosomal analysis. Of the 182 patients, group I (NT 95-99th centile ) included 92 patients and group II 90 patients. Chromosomal abnormalities were present in 50 (27.4%), 14 (7.6%) in group I, and 36 (19.4%) in group II. Of the 132 euploid pregnancies, adverse outcomes were present in 22 (16%) fetuses, 7 (5.3%) in group I, and 15(11.7%) in group II. A normal outcome was present in 110 (60.4%) pregnancies of the 182 fetuses with NT more than or equal to 95th centile. Normal outcome observed in group I was 77.1% and in group II, it was 43.4%.Conclusion An increased NT is associated with poor perinatal outcomes in 39.6% patients. Chromosomal analysis and follow-up for adverse outcome in fetuses with NT more than or equal to 95th centile is important to enable a take home neonatal rate of 60.4%. No pregnancy with increased NT should be discontinued without detailed fetal evaluation for genetic disorders, structural malformation, and fetal growth.