Non-invasive DNA test for children\’s gender Non-invasive DNA test refers to using cell fragments in blood, saliva and other human bodies to determine the characteristics of a certain DNA fragment on the chromosome to determine the individual\’s genetic type and obtain relevant information. Non-invasive DNA test for child gender is one of the applications. This article will explain it in detail from four aspects: detection principle, sample collection, data interpretation and precautions. 1. Detection Principle Non-invasive DNA testing of a child’s gender mainly relies on free fetal DNA in plasma.