Table 6 Mixed effects models for weight and length in syphilis-exposed and -unexposed children*.

From: Growth in syphilis-exposed and -unexposed uninfected children from birth to 18 months of age in China: a longitudinal study

Variables

Weight (kg)**

Length (cm)***

β

SE

95% CI

t

P

β

SE

95% CI

t

P

Fixed effects

Intercept

3.84

0.14

(3.57, 4.11)

28.16

<0.001

51.67

0.58

(50.53, 52.81)

89.11

<0.001

Group

0.03

0.05

(−0.08, 0.14)

0.58

0.56

0.15

0.25

(−0.34, 0.65)

0.61

0.54

Age (month)

0.97

0.03

(0.90, 1.03)

30.08

<0.001

3.38

0.16

(3.07, 3.69)

21.36

<0.001

Age2 (month2)

−0.03

0.002

(−0.035, −0.028)

−18.96

<0.001

−0.10

0.008

(−0.11, −0.08)

−12.03

<0.001

Group × Age

0.02

0.02

(−0.01, 0.05)

1.60

0.11

−0.06

0.08

(−0.21, 0.09)

−0.76

0.44

Group × Age2

−0.001

0.0008

(−0.003, 0.0003)

−1.56

0.12

0.002

0.004

(−0.005, 0.01)

0.64

0.52

Sex

−0.11

0.05

(−0.20, −0.009)

−2.14

0.03

−0.44

0.24

(−0.91, 0.03)

−1.85

0.06

Sex × Age

−0.10

0.02

(−0.13, −0.07)

−6.55

<0.001

−0.14

0.07

(−0.28, 0.01)

−1.83

0.07

Sex × Age2

0.005

0.0008

(0.003, 0.006)

6.08

<0.001

0.007

0.004

(−0.0007, 0.01)

1.79

0.07

Maternal education

Primary or less

0.006

0.10

(−0.19,0.20)

0.06

0.95

−0.56

0.31

(−1.17, 0.05)

−1.8

0.07

Secondary

0.02

0.06

(−0.10,0.13)

0.28

0.78

−0.13

0.19

(−0.50, 0.24)

−0.70

0.48

College or above

—

—

—

—

—

—

—

—

—

—

Income (CNY)

0.35

3.49

(−6.5,7.19)

0.10

0.92

0.02

0.01

(−0.004, 0.04)

1.60

0.11

Underweight at birth

−1.08

0.18

(−1.44,−0.72)

−5.89

<0.001

—

—

—

—

—

Random effects

Intercept

<0.001

—

 

—

—

<0.001

—

 

—

—

Age

0.007

0.002

 

3.16

<0.001

0.17

0.006

 

4.16

<0.001

Age2

<0.001

<0.001

 

1.43

0.08

<0.001

—

 

—

—

Residual

0.43

0.01

 

31.46

<0.001

10.31

0.34

 

30.74

<0.001

  1. *β = coefficient estimate, SE = standard error. Number of infants = 544 for weight and 539 for length. Number of measurements = 2982 for weight and 2951 for length. Group = 1 for the syphilis-exposed uninfected condition and 2 for the unexposed uninfected condition, sex = 1 for a boy and 2 for a girl.
  2. **Adjusted for maternal education (primary or less, secondary, college or above), family income (as continuous variables), and underweight at birth.
  3. ***Adjusted for maternal education (primary or less, secondary, college or above) and family income (as continuous variables).
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