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Table 1 Characteristics of the study subjects according to the method of pregnancy

From: The risk of secondary sex ratio imbalance and increased monozygotic twinning after blastocyst transfer: data from the Japan Environment and Children’s Study

Characteristics

Spontaneous conception

Non-ART treatment

CT

BT

Spontaneous vs Non-ART treatment vs CT and BT

Mother (Pregnancies) (n)

92,022

3546

728

2020

 

 Age (year)

30.4 ± 5.0

32.7 ± 4.2

35.6 ± 4.0

35.6 ± 3.9

<.0001

 BMI (kg/m2)

21.2 ± 3.3

21.4 ± 3.6

21.3 ± 3.0

21.3 ± 3.1

<.0001

 Metabolic equivalent/min

414.1 ± 732.9

334.8 ± 604.6

256.0 ± 488.1

258.6 ± 462.5

<.0001

 Calorie intake

385.4 ± 729.3

318.0 ± 597.4

235.0 ± 453.0

249.5 ± 551.8

<.0001

 Low education (%)

37.3

22.4

21.9

22.8

<.0001

 Smoking habit (%)

18.9

8.5

4.4

4.8

<.0001

 Alcohol consumption habit (%)

65.6

63.2

60.6

62.4

<.0001

 Physical component summary (SF-8 score)

45.3 ± 5.3

44.1 ± 7.6

43.7 ± 7.9

43.8 ± 8.2

<.0001

 Mental component summary (SF-8 score)

46.1 ± 7.3

46.9 ± 7.1

47.6 ± 7.2

47.0 ± 7.0

<.0001

 Assessing depression (K6 score)

3.7 ± 3.9

3.2 ± 3.4

2.8 ± 3.0

3.0 ± 3.4

<.0001

 Hyperlipidemia (%)

0.5

1.3

0.5

0.7

<.0001

 Diabetes (%)

0.2

0.4

0.5

0.5

<.0001

 Hyperthyroidism (%)

1.0

1.3

1.4

1.8

0.001

 Hypothyroidism (%)

0.9

2.1

3.4

3.9

<.0001

Family

 Low income (%)

41.5

26.8

16.7

20.2

<.0001

Father (n)

47,208

1929

410

1082

 

 Age (year)

32.4 ± 5.8

34.4 ± 5.2

37.2 ± 5.4

37.6 ± 5.5

<.0001

 BMI (kg/m2)

23.4 ± 3.5

23.5 ± 3.4

23.9 ± 3.2

23.8 ± 3.3

<.0001

 Low education (%)

45.1

31.3

30.3

32.3

<.0001

 Smoking habit (%)

51.2

38.7

33.8

33.6

<.0001

 Alcohol consumption habit (%)

78.8

78.0

78.1

80.1

NS

 Physical component summary (SF-8 score)

51.0 ± 5.3

51.1 ± 5.3

51.2 ± 4.7

50.9 ± 5.3

NS

 Mental component summary (SF-8 score)

49.8 ± 6.1

49.9 ± 6.2

50.0 ± 6.2

50.1 ± 5.9

NS

 Assessing depression (K6 score)

2.6 ± 3.5

2.5 ± 3.4

2.3 ± 3.2

2.5 ± 3.5

NS

Infants (n)

92,545

3696

751

2102

 

 Male (%) (95% CI)

51.3 (49.2–53.4)

50.7(48.6–52.8)

48.9 (45.3–52.5)

53.4 (51.3–55.5)

NS

 Sex ratio

1.05

1.03

0.96

1.15

 

Pregnancies (n)

92,022

3546

728

2020

 

 Single (%)

99.4

95.8

96.8

95.9

<.0001

 Multiple (%)

0.6

4.2

3.2

4.1

 

  [Monozygotic twinning (%)] (95% CI)

0.27 (0.23–0.30)

0.11 (0–0.22)

0.27 (0–0.65)

0.99 (0.56–1.42)

<.0001

  1. Data are shown as mean ± SD (The percentages are drawn from available data and the total number varies for each category because of missing values and refer to the Additional file 2.). Smoking and alcohol consumption habits at pregnancy recognition, SF-8 score of 50 or less. Low education: defined by the highest academic background and categorized as graduation from high school or less, Low income: defined by the annual revenue of the household and categorized as an annual income of 4,000,000 Japanese yen or less. The P values are listed simply to give an indication of the magnitude of the inter-group differences. It is not intended that all those P values should have the customary probabilistic interpretation
  2. BMI (body mass index), CT (early cleavage-stage embryo transfer), BT (blastocyst transfer), NS (not statistically significant)
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Reproductive Biology and Endocrinology

ISSN: 1477-7827

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