Objective: To investigate whether chromosomally normal fetuses with a nuchal translucency (NT) ≥ 99th percentile(3.5 mm) in the first trimester have an increased risk of delayed development at 2 years of age.
Methods: The study included children of women from 10 Danish hospitals who had fetal NT either ≥ 99th percentile (Group 1) or <95th percentile (Group 2) in the first trimester. The groups were matched by gender,gestational age at birth and maternal age. There were twice as many children in Group 2 as in Group 1. Follow-up was conducted at 2 years of age, infant development being assessed by the 'Ages and Stages Questionnaire'. The cutoff value for delayed development was defined as the 5th percentile from the first 100 questionnaires from Group 2.
Results: In a 1-year period 202 of 33 266 fetuses (0.6%)had NT ≥ 3.5 mm. Of these, 99 (49.0%) were liveborn with normal karyotype and normal ultrasound findings during pregnancy. The response rate to the ASQ was 83.3% in Group 1 and 71.4% in Group 2. A low ASQ score was found in 1.3% (1/80) and 4.4% (6/137)in Groups 1 and 2, respectively (P = 0.265), but no difference was found in the mean ASQ score between the two groups (P = 0.160).
Conclusion: Fetuses with NT ≥ 99th percentile, normal karyotype and normal ultrasound findings during pregnancy had no increased risk of developmental delay at 2 years of age compared with fetuses with normal NT(<95th percentile).