Influence of the gender of the foetus on risk markers used in the prenatal screening of trisomy 21

Abstract

Introduction: In first trimester combined screening, biochemical and ultrasound markers are used that are modified by different factors such as weight, twins, smoking, etc. The aim of this study is to analyse the influence of foetal gender on these markers, and the repercussion on the result of the screening of trisomy 21. Material and methods: An observational, descriptive and retrospective study (2013-2015) was conducted. Multiple gestations were excluded. Variables analysed: nuchal translucency, free human chorionic gonadotrophin concentration, pregnancy-associated plasma protein A, and their median corrected multiples. A comparison was made of the medians of the variables in gestations with male and female foetuses, affected and non-affected. Results: There was a 23.62% increase in the median of the median corrected multiple free human chorionic gonadotrophin and 3.65% in the median of the median corrected multiple pregnancy-associated plasma protein A, in gestations with female foetuses. This increase is observed in gestations with foetuses affected and non-affected by trisomy 21. Male gender: detection rate 86.9%, false positive rate 3.36%. Female gender: detection rate 90.9%, false positive rate 4.10%. Conclusions: The increase, especially in free human chorionic gonadotrophin levels, leads to an increase in detection rate and false positive rate in gestations with a female foetus. The application of a correction factor by gender requires cost-effectiveness studies.