Effect of blastocyst quality on human sex ratio at birth in a single blastocyst frozen thawed embryo transfer cycle

Figures & data

Figure 1. Flowchart showing data selection process for analysis.

Table 1. Characteristics of 3041 patients following the SBFET cycles performed from 2017 to 2020.

Characteristic	Description
Number of cycles	3041
The sex of birth
Male	1683 (55.34)
Female	1358 (44.66)
Female age (years)	30.66 ± 3.83
20-29	1200 (39.46)
30-39	1791 (58.90)
40-49	50 (1.64)
Type of infertility
Primary	1695 (55.74)
Secondary	1346 (44.26)
Main infertility cause
Male factor	510 (16.77)
Female factor	1998 (65.70)
Mixed factor (both male and female factors)	425 (13.98)
Unexplained infertility	108 (3.55)
Infertility duration	4.37 ± 2.80
0-3.00	1400 (46.04)
3.01-5.00	826 (27.16)
5.01-10.00	712 (23.41)
>10	103 (3.39)
Maternal BMI (kg/m^2)	21.70 ± 3.18
<18.50	359(11.81)
18.50-23.99	2000 (65.77)
24.00-27.99	556 (18.28)
28.00-31.99	112 (3.68)
≥32	14 (0.46)
Fertilization method
IVF	2244 (73.79)
ICSI	797 (26.21)
Day of embryo transfer
D5	2628 (86.42)
D6	413 (13.58)
First FET
Yes	2182 (71.75)
No	859 (28.25)
Birth type
Twins	48 (1.58)
Singletons	2993 (98.42)
Gestational age(weeks)
<28	11 (0.36)
28-36	282 (9.27)
37-42	2746 (90.30)
>42	2 (0.07)
Blastocyst quality
High quality	2748 (90.37)
Low quality	293 (9.63)
Expansion
3	130 (4.27)
4	2789 (91.71)
5	111 (3.65)
6	11 (0.36)
ICM
A	1501 (49.36)
B	1502 (49.39)
C	38 (1.25)
TE
A	886 (29.14)
B	1900 (62.48)
C	255 (8.38)

Table 2. SSR stratified by different characteristics.

	Males	Females	Sex ratio(M/F)	X^2	p-value
N (%)	1683	1358	1.24
Maternal age (years)	30.63 ± 3.75	30.72 ± 3.93		15.705	<.001
20-29	662	538	1.23
30-39	1007	784	1.28
40-49	14	36	0.39
Type of infertility				0.131	.718
Primary	943	752	1.25
Secondary	740	606	1.22
Main infertility cause				3.987	.263
Male factor	266	244	1.09
Female factor	1130	868	1.30
Mixed factor (both male and female factors)	231	194	1.19
Unexplained infertility	56	52	1.08
Infertility duration	4.31 ± 2.68	4.44 ± 2.94		1.856	.603
0-3.00	769	631	1.22
3.01-5.00	473	353	1.34
5.01-10.00	386	326	1.18
>10	55	48	1.15
Maternal BMI(kg/m^2)	21.70 ± 3.26	21.51 ± 3.07		4.098	.393
<18.50	196	163	1.20
18.50-23.99	1102	898	1.23
24.00-27.99	307	249	1.23
28.00-31.99	67	45	1.49
≥32	11	3	3.67
Fertilization method				0.255	.619
IVF	1248	996	1.25
ICSI	435	362	1.20
Day of embryo transfer				0.334	.595
D5	1449	1179	1.23
D6	234	179	1.31
First FET				1.179	.292
Yes	1221	961	1.27
No	462	397	1.16
Birth type				0.563	.468
Twins	24	24	1.00
Singletons	1659	1334	1.24
Gestational age(weeks)				3.13	.372
<28	4	7	0.57
28-36	166	116	1.43
37-42	1512	1234	1.23
>42	1	1	1.00

Table 3. SSR stratified by blastocyst quality and morphology.

	Males	Females	Sex ratio (M/F)	X^2	p-value
Blastocyst quality				9.671	.002
High quality	1546	1202	1.29
Low quality	137	156	0.88
Expansion				3.432	.330
3	68	62	1.10
4	1539	1250	1.23
5	68	43	1.58
6	8	3	2.67
ICM				0.171	.918
A	828	673	1.23
B	835	667	1.25
C	20	18	1.11
TE				26.811	<.001
A	548	338	1.62
B	1018	882	1.15
C	117	138	0.85

Table 4. SSR following SBFET cycles by different grades of trophectoderm (TE)

and inner cell mass (ICM).

ICM	TE	Males	Females	Sex ratio (M/F)	X^2	p-value
A	A	368	242	1.52	22.466	<.001
	B	451	410	1.10
	C	9	27	0.33
B	A	176	107	1.64	8.221	.016
	B	551	444	1.24
	C	108	110	0.98
C	A	4	1	4.00	1.73	.344
	B	16	17	0.94

Table 5. Multivariate analysis of potential factors associated with SSR.

	aOR (95% CI)	p-value
Blastocyst quality
High quality	1.466 (1.151-1.868)	.002
Low quality	Reference
Expansion
3	0.411 (0.104-1.620)	.204
4	0.454 (0.120-1.720)	.245
5	0.582 (0.146-2.319)	.442
6	Reference
ICM
A	1.110 (0.582-2.118)	.751
B	1.133 (0.594-2.160)	.705
C	Reference
TE
A	1.914 (1.445-2.537)	<.001
B	1.360 (1.046-1.769)	.022
C	Reference