Table 2 Patient demographics and IVF outcomes, by number of retrieved oocytes

No. treatment cycles (n)

4870

10,106

3296

Age (years), x̄ ± SD

32.40 ± 5.20

30.09 ± 4.69

28.48 ± 4.16

724.77

< 0.0001

BMI (kg/m²), x̄ ± SD

22.06 ± 3.11

21.83 ± 3.02

21.74 ± 3.07

12.36

< 0.0001

AFC, Median [IQR]

9 [6,12]

13 [10,17]

16 [12,20]

2252.7981

< 0.0001

Total dose of gonadotropins (IU), Median [IQR]

2,700 [2,025, 3,525]

2,100 [1,537.5, 2,775]

1,762.5 [1,350, 2,475]

1685.9298

< 0.0001

Duration of ovarian stimulation (days), x̄ ± SD

11.35 ± 2.21

11.70 ± 2.10

12.22 ± 2.46

153

< 0.0001

LH on hCG trigger day (IU/L), Median [IQR]

0.93 [0.6,1.4]

0.88 [0.57,1.36]

0.79 [0.49,1.23]

107.741

< 0.0001

P on hCG trigger day (ng/mL), Median [IQR]

0.658 [0.43, 0.89]

0.82 [0.58, 1.07]

0.98 [0.711, 1.28]

1272.15

< 0.0001

E2 on hCG trigger day (pg/mL), Median [IQR]

1,214 [879.1, 1,670]

2,184 [1,635, 2,913]

3,478 [2,602.22, 4,608.5]

6.943.40

< 0.0001

Endometrial thickness on hCG trigger day (mm), Median [IQR]

10.6 [9, 12.4]

10.9 [9.4, 12.6]

10.8 [9.2, 12.5]

51.1977

< 0.0001

Oocytes retrieved, x̄ ± SD

6.05 ± 1.79

12.53 ± 2.47

22.27 ± 5.01

29,589.6

< 0.0001

No. available embryos, Median [IQR]

2 [1 3]

3[2,4]

5 [3,7]

3742.67

< 0.0001

No. fresh embryos transferred, x̄ ± SD

1.80 ± 0.41

1.86 ± 0.35

1.64 ± 0.48

258.05

< 0.0001

Time to live birth (days), x̄ ± SD

320.96 ± 98.26

330.08 ± 266.13

383.77 ± 187.53

65.79

< 0.0001

Cancellation rate with no available embryos, n (%)

627/4,870 (12.87%)

458/10,106 (4.53%)

80/3,296 (2.43%)

488.223

< 0.0001

Cycle cancellation for high risk of OHSS, n (%)

14/4,870 (0.29%)

305/10,106 (3.02%)

782/3,296 (23.73%)

2268.21

< 0.0001

Moderate-to-severe OHSS rate, n (%)

4/4,870 (0.08%)

211/10,106 (2.09%)

112/3,296 (3.4%)

134.413

< 0.0001

CLBR/cycle started, n (%)

2,314/4,870 (47.52%)

7,143/10,106 (70.68%)

2,717/3,296 (82.43%)

1244.99

< 0.0001

No. fresh transfer cycles (n)

4057

8878

1922

No. embryos transferred

504.44

< 0.0001

 1

826/4057(20.36%)

1240/8878(13.97%)

685/1922(35.64%)

 2

3231/4057(79.64%)

7638/8878(86.03%)

1237/1922(64.36%)

Embryo transfer type

1610.83

< 0.0001

 Cleavage embryo

3933/4057(96.94%)

8296/8878(93.44%)

1283/1922(66.75%)

 Blastocyst

124/4057(3.06%)

582/8878(6.56%)

639/1922(33.25%)

HCG positive rate

2713/4057(66.87%)

6889/8878(77.6%)

1561/1922(81.22%)

215.12

< 0.0001

Clinical pregnancy rate

2431/4057(59.92%)

6378/8878(71.84%)

1470/1922(76.48%)

240.7

< 0.0001

Abortion rate

347/2431(14.27%)

557/6378(8.73%)

92/1470(6.26%)

84.83

< 0.0001

Live birth rate

2044/4057(50.38%)

5743/8878(64.69%)

1361/1922(70.81%)

320.48

< 0.0001