High sensitivity and specificity in fetal gender identification in the first trimester, using ultrasound and Noninvasive Prenatal Screening (NIPS) in twin pregnancies, a prospective study

Table 2 Accuracy of gender determination at first trimester according to birth’s gender, CRL levels and Y chromosome test

	Birth’s gender n (%)		Sensitivity of gender determination		PPV of gender determination		Accuracy of gender determination	OR (95% CI)
	Male	Female	Male	Female	Male	Female	n / N (%)
US at 1^st trimester
Male	61 (68.5)	9 (9.7)	68.5	90.3	87.1	75.0	145 / 182 (79.7)	20.3
Female	28 (31.5)	84 (90.3)						(8.0–45.2)
CRL 45–54
Male	6 (25.0)	4 (16.7)	25.0	83.3	60.0	52.6	26 / 48 (54.2)	1.7
Female	18 (75.0)	20 (83.3)						(0.4–6.9)
CRL 55–67
Male	30 (85.7)	3 (10.0)	85.7	90.0	90.9	84.4	57 / 65 ([1])	54.0
Female	5 (14.3)	27 (90.0)						(11.8–247.6)
CRL 68–84
Male	23 (88.5)	1 (4.8)	88.5	95.2	95.8	87.0	43 / 47 (91.5)	153.3
Female	3 (11.5)	20 (95.2)						(14.8–1593.6)
Y chromosome^a							95 / 95 (100)

US ultrasound, CRL crown rump length, CRL range – weeks 11, 12, 13 according to Fetal Medicine Foundation scale (https://fetalmedicine.org/research/pregnancyDating). N- Sample size of accuracy group, N – group’s total sample size, %—total accuracy of gender determination. OR odd’s ration, CI confidence interval
^aSuccess in determining the gender using the Y chromosome test (Yes = accuracy was successful when the Y chromosome was found in cases of twins of M/M, M/F, F/M (M- male, female) or after reduction/one embryo loss and only one newborn – M, and when there was no Y chromosome in the cases of F/F or F. No = Y chromosome was found in cases of F/F or F

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