A computer implemented method for assessing an extent of genetic mosaicism in a genetic screening test of circulating cell free nucleic acid from a pregnant female subject, comprising: (a) obtaining, by a computing system, positive screening results from a genetic screening test for presence of one or more aneuploidies in a sample comprising circulating cell free nucleic acid from a pregnant female subject; (b) obtaining, by the computing system, data from the genetic screening test, wherein the data identifies a genetic copy number variation region within the circulating cell free nucleic acid that comprises a copy number variation and the circulating cell free nucleic acid comprises maternal nucleic acid and fetal nucleic acid, wherein the genetic screening test is a noninvasive prenatal testing (NIPT); (c) quantifying, by the computing system using the data, a fraction of nucleic acid having the copy number variation in the circulating cell free nucleic acid; (d) quantifying, by the computing system using the data, a fraction of the fetal nucleic acid in the circulating cell free nucleic acid; (e) determining, by the computing system, a mosaicism ratio, wherein the mosaicism ratio is the fraction of nucleic acid having the copy number variation in the circulating cell free nucleic acid divided by the fraction of the fetal nucleic acid in the circulating cell free nucleic acid; (f) in response to determining the mosaicism ratio is between 0.1 to 0.7, classifying, by the computing system, a presence of a genetic mosaicism for the copy number variation region; and (g) providing, by the computing system, an interpretation of the positive screening results from the genetic screening test as positive with a comment concerning possibility of a mosaic presentation. (a) obtaining, by a computing system, positive screening results from a genetic screening test for presence of one or more aneuploidies in a sample comprising circulating cell free nucleic acid from a pregnant female subject; (b) obtaining, by the computing system, data from the genetic screening test, wherein the data identifies a genetic copy number variation region within the circulating cell free nucleic acid that comprises a copy number variation and the circulating cell free nucleic acid comprises maternal nucleic acid and fetal nucleic acid, wherein the genetic screening test is a noninvasive prenatal testing (NIPT); (c) quantifying, by the computing system using the data, a fraction of nucleic acid having the copy number variation in the circulating cell free nucleic acid; (d) quantifying, by the computing system using the data, a fraction of the fetal nucleic acid in the circulating cell free nucleic acid; (e) determining, by the computing system, a mosaicism ratio, wherein the mosaicism ratio is the fraction of nucleic acid having the copy number variation in the circulating cell free nucleic acid divided by the fraction of the fetal nucleic acid in the circulating cell free nucleic acid; (f) in response to determining the mosaicism ratio is between 0.1 to 0.7, classifying, by the computing system, a presence of a genetic mosaicism for the copy number variation region; and (g) providing, by the computing system, an interpretation of the positive screening results from the genetic screening test as positive with a comment concerning possibility of a mosaic presentation.