Table 1 Descriptive statistics and regression coefficients for the difference in birth size of dizygotic twin boys and girls according to the sex of their co-twin (reference group same-sex dizygotic twins).

From: Birth size and gestational age in opposite-sex twins as compared to same-sex twins: An individual-based pooled analysis of 21 cohorts

 

SS

OS

B

p-value

CIs

n

Mean

SD

n

Mean

SD

Boys

Birth weight (kg)

17584

2.578

0.57

16417

2.608

0.56

0.031

<0.001

0.018

0.045

Birth length (cm)

8702

47.42

3.28

8170

47.60

3.30

0.160

0.006

0.045

0.274

PI at birth (kg/m3)

8702

24.41

3.12

8170

24.44

3.13

0.021

0.691

−0.083

0.125

Girls

Birth weight (kg)

17432

2.495

0.54

16417

2.497

0.54

0.005

0.466

−0.008

0.018

Birth length (cm)

8128

46.94

3.14

8170

46.85

3.28

−0.089

0.125

−0.202

0.025

PI at birth (kg/m3)

8128

24.45

3.21

8170

24.46

3.18

0.005

0.933

−0.103

0.113

  1. Participating twin cohorts in this study: Australian Twin Registry, Carolina African American Twin Study of Aging, Child and Adolescent Twin Study in Sweden, East Flanders Prospective Twin Survey, Finntwin12, Finntwin16, Gemini Study, Guinea-Bissau Twin Study, Hungarian Twin Registry, Italian Twin Registry, Japanese Twin Cohort, Longitudinal Israeli Study of Twins, Michigan Twins Study, Minnesota Twin Registry, Mongolian Twin Registry, Peri/Postnatal Epigenetic Twins Study, Qingdao Twin Registry of Children, Quebec Newborn Twin Study, Twins Early Developmental Study, West Japan Twins and Higher Order Multiple Births Registry and Young Netherlands Twin Registry.
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