Noninvasive prenatal testing (NIPT) results are less accurate the later applied during pregnancy.

OBJECTIVE: Noninvasive prenatal testing (NIPT) has been introduced in prenatal genetics, recently. Even though it is connected with biological, technical, medical and ethical issues also reviewed here, it is meanwhile applied as a standard screening test. One of the obvious, but yet not further reviewed peculiarities of NIPT is that the reported false positives rates are variant, specifically in European, compared with Chinese publications.

MATERIALS AND METHODS: Here the only 15 suited studies on >600,000 cases were identified in which at least average pregnancy age was reported for the time NIPT was done.

RESULTS AND CONCLUSION: It could be shown, that NIPT is done in China in later weeks of gestation, than in other countries. Besides, here for the first time it is highlighted that false positive NIPT results are less frequent, the earlier the screening is performed. Most likely this is related to two biological phenomena: loss of trisomic pregnancies and preferential survival of fetuses which underwent trisomic rescue, however, with major trisomic populations in placenta. This yet not considered aspect needs to be kept in mind especially in late stage high risk pregnancies.