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Table 1 Characteristics of the FET cycles for each study group

From: Effect of body mass index on pregnancy outcomes in a freeze-all policy: an analysis of 22,043 first autologous frozen-thawed embryo transfer cycles in China

Characteristics

Underweight (< 18.5 kg/m2)

Normal weight (18.5–22.9 kg/m2)

Overweight (23–27.4 kg/m2)

Obese (≥ 27.5 kg/m2)

P valuea

P valueb

P valuec

Patients, n

2527

13,224

5079

1213

 

Age (years)

30.56 ± 3.61

31.36 ± 3.73

31.66 ± 3.79

31.11 ± 3.79

< 0.001

< 0.001

0.023

BMI (kg/m2)

17.66 ± 0.73

20.67 ± 1.21

24.68 ± 1.22

29.89 ± 2.39

< 0.001

< 0.001

< 0.001

Infertility duration (years)

3.19 ± 2.37

3.36 ± 2.75

3.68 ± 2.90

4.10 ± 2.97

0.004

< 0.001

< 0.001

Gravidity

< 0.001

0.121

0.448

 0

1577(62.4)

7393(55.9)

2756(54.3)

672(55.4)

 

 1

556(22.0)

3042(23.0)

1199(23.6)

297(24.5)

 ≥ 2

394(15.6)

2789(21.1)

1124(22.1)

244(20.1)

Parity

< 0.001

0.002

0.520

 0

2418(95.7)

12,220(92.4)

4614(90.8)

1120(92.3)

 

 1

105(4.2)

938(7.1)

429(8.5)

84(6.9)

 ≥ 2

4(0.2)

66(0.5)

36(0.7)

9(0.7)

Main cause of infertility

0.007

< 0.001

< 0.001

 Tubal factor

1341(53.1)

7198(54.4)

2666(52.5)

553(45.6)

 

 PCOS

162(6.4)

1077(8.1)

796(15.7)

346(28.5)

 Diminish ovarian reserve

183(7.2)

875(6.6)

278(5.5)

41(3.4)

 Endometriosis

261(10.3)

1179(8.9)

307(6.0)

44(3.6)

 Uterine factor

75(3.0)

426(3.2)

175(3.4)

26(2.1)

 Unexplained

94(3.7)

424(3.2)

136(2.7)

46(3.8)

 Male factor

411(16.3)

2045(15.5)

721(14.2)

157(13.9)

Number of OPU prior to FET

0.043

< 0.001

< 0.001

 1

1962(77.6)

10,028(75.8)

3689(72.6)

824(67.9)

 

 2

338(13.4)

2026(15.3)

895(17.6)

241(19.9)

 ≥ 3

227(9.0)

1170(8.8)

495(9.7)

148(12.2)

Fertilization method

0.744

0.789

0.584

 IVF

1605(63.5)

8470(64.1)

3252(64.0)

795(65.5)

 

 ICSI

601(23.8)

3145(23.8)

1225(24.1)

277(22.8)

 IVF+ ICSI

321(12.7)

1609(12.2)

602(11.9)

141(11.6)

Year of treatment

0.659

< 0.001

0.037

 2010–2012

550(21.8)

2836(21.4)

932(18.4)

222(18.3)

 

 2013–2014

881(34.9)

4736(35.8)

1809(35.6)

453(37.3)

 2015–2017

1096(43.4)

5652(42.7)

2338(46.0)

538(44.4)

  1. aUnderweight vs. normal weight
  2. bOverweight vs. normal weight
  3. cObese vs. normal weight
  4. Data are presented as mean ± SD for continuous variables and n (%) for dichotomous variables