Premium
Nuchal translucency in twins according to mode of assisted conception and chorionicity
Author(s) -
Maymon R.,
Cuckle H.,
Svirsky R.,
Sheena L.,
Melcer Y.,
Rozen H.,
BenAmi I.
Publication year - 2014
Publication title -
ultrasound in obstetrics and gynecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.202
H-Index - 141
eISSN - 1469-0705
pISSN - 0960-7692
DOI - 10.1002/uog.13278
Subject(s) - medicine , obstetrics , retrospective cohort study , percentile , nuchal translucency , gynecology , wilcoxon signed rank test , pregnancy , single center , gestation , mann–whitney u test , first trimester , surgery , statistics , mathematics , biology , genetics
Objectives The impact of nuchal translucency ( NT ) screening in twins conceived after use of assisted reproduction technology ( ART ) has not been addressed properly in the literature. The aim of the current study was to assess, in a large cohort from a single center, NT in twins following various modes of ART as compared with NT in spontaneously‐conceived twins and to differentiate results with regard to chorionicity. Methods Retrospective data from 825 twin pregnancies were available for this study. All pregnant women underwent NT screening and chorionicity determination between 11 + 0 and 13 + 6 weeks' gestation in our center. Information about mode of conception and pregnancy outcome was obtained from hospital records and by telephone interviews. Twins were classified as having been conceived after in‐vitro fertilization ( IVF ) with the woman's own or a donated embryo, after non‐ IVF ART or spontaneously. NT distribution in subgroups of fetuses was compared on the basis of the multiple of the normal median ( MoM ), SD of log 10 MoM estimated by the 90 th –10 th centile range divided by 2.563 and the proportion of NT values exceeding the normal 95 th centile which was 1.641 MoM in the singletons. Results NT values were statistically significantly higher in ART pregnancies as compared with spontaneously‐conceived pregnancies (Wilcoxon rank‐sum test, P < 0.05) with medians of 1.073 and 1.038 MoM , respectively, but the proportion with values above the normal 95 th percentile did not differ (chi‐square test, P = 0.89). Among the ART twins, NT values were significantly higher for those conceived using IVF methods ( P < 0.005), with a median of 1.082 MoM , compared with a median of 1.022 MoM using other methods. However, although a greater proportion exceeded the 95 th centile (7.3% compared with 4.8%) this difference did not reach statistical significance ( P = 0.17). There were no differences in NT values according to chorionicity (Wilcoxon rank‐sum test, P = 0.75). The standard deviation of log 10 NT was similar for all subgroups of twins. The correlation coefficient between fetuses in ART pregnancies was statistically significantly lower than that in spontaneously‐conceived pregnancies ( P < 0.05) but no significant differences were found between types of ART or according to chorionicity. Conclusions There was a small but significant increase in NT levels among ART pregnancies, which appeared to be confined to those conceived using IVF , and a small reduction in the correlation between fetuses. These effects probably have little impact on the estimated risk based on algorithms in use today. Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd.