Volume 51, Issue 10, December 2022, 102482AbstractIntroduction

Increased fetal nuchal translucency is associated with chromosomal as well as morphological abnormalities. The psychomotor development of children from these pregnancies is still unclear. The main objective of our study was to evaluate pregnancy outcomes and the post-natal progress of fetuses with increased nuchal translucency. We also compared the features of patients and fetuses according to their nuchal translucency measurement (above 3.5 mm or not).

Methods

Retrospective single-center study in 398 patients in a level 3 maternity unit in France. Mothers whose fetus had a nuchal translucency higher than the 95 th percentile between 2009 and 2018 were included. All patients who had a child with a normal karyotype were prospectively given a questionnaire to evaluate their child's psychomotor development.

Results

37.4% (130/348) of fetuses had a chromosomal abnormality and 2.3% (5/218) had a normal karyotype but a pathogenic copy number variant diagnosed by array- CGH. 28.7% (77/268) of fetus without diagnosed chromosomal abnormalities, presented a morphological abnormality with predominant cardiac malformations. Fetuses with a nuchal translucency ≥ 3.5 mm, had more chromosomal abnormalities (p<0.0001) and were at higher risk of hypotrophy (p=0.005) and birth by cesarean (p=0.04). Among the liveborn children, 70% (166/238) were healthy without morphological or chromosomal abnormalities. Lastly, 17% (17/102) of these children had psychomotor disorder.

Conclusion

According to our results, parents should be warned of the increased risk of hypotrophy and delivery by cesarean section for fetuses with a nuchal translucency ≥ 3.5 mm. We recommend prolonged specialized pediatric follow-up for children who have been carriers of increased nuchal translucency.

Introduction

Increased nuchal translucency, defined as nuchal translucency (NT) measurement above the 95th percentile in the first trimester of pregnancy, is primarily suggestive of chromosomal abnormalities [1]. The most frequently encountered abnormalities are aneuploidies (69% of fetuses when the NT is greater than 3 mm) [2].

In France, if NT is greater than or equal to 3.5 mm or less than 3.5 mm with a high risk of trisomy 21 (serum maternal markers greater than 1/50), patients are offered invasive fetal sampling to study the karyotype [3] and to perform chromosomal analysis by array-CGH [4,5] for NT greater than or equal to 3.5 mm.

Apart from any chromosomal abnormality, increased NT can also be associated with various malformations or genetic syndromes (e.g. Noonan syndrome). It has been described as possibly being associated with an increased risk of in utero fetal death (IUFD) and late miscarriage (LM) [6]. Furthermore, the pregnancy outcomes and the psychomotor development in children with increased NT without associated chromosomal abnormalities is not well established [7,8].

The main objective of our work was to study pregnancy outcomes and to evaluate the psychomotor development of children with increased NT. We also compared patients with NT greater than or equal to 3.5 mm and those with NT greater than the 95th percentile but less than 3.5 mm.

Section snippetsMaterial and methods

This study complied with the Helsinki guidelines for human research and was approved by the Angers review board (19.08.16.59740; 2019/73) on 10 October 2019. A no-objection form was sent to all the patients.

This retrospective and prospective, single-center study was conducted in a level 3 maternity unit in the Prenatal Diagnosis Unit of the Limoges Mother and Child Hospital (LMCH), in France, from 2009 to 2018.

Singleton pregnancies or dichorionic-diamniotic twin pregnancies with NT measurement

Results

Of the 12,952 patients who had a first-trimester ultrasound at LMCH between 2009 and 2018, 438 were followed up for increased NT (3.4%) and 28 are lost to follow-up. After exclusion of 12 patients, we included 398 patients (Fig. 1). Patient data are described in Table 1.

Of the 398 patients whose fetuses had NT, 250 had blood test for Down syndrome screening. Among them, 56.8% (142/250) were in a high-risk group with HT21 in the 1st or 2nd trimester > 1/50.

Of the 398 patients, 348 (87%) had

Discussion

Increased NT can reveal chromosomal and morphological abnormalities. In the general population, increased NT (> 3mm) affects between 0.5% and 1.75% of embryos [10,11]. Three percent of the patients in our hospital were affected of such abnormalities between 2009 and 2018. Our higher percentage is related to the fact that we studied NT ≥ 95th percentile.

In our study, half of the patients were in a high-risk group for trisomy 21. One-third (37.4%) of the patients had a fetus with a chromosomal

Conclusion

Increased NT is linked in one-third of cases to a chromosomal abnormality and in one-third of cases to a morphologic abnormality such as cardiac malformation when the karyotype is normal. In our study, 70% (166/238) of the children alive had no morphological nor chromosomal abnormalities. This information should be given to couples whose fetus has increased NT, along with psychological support for the anxiety caused by the announcement and the increased monitoring of the pregnancy. Among the

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