Table 3 Summary statistics of the ultrasound data of 190 low-risk pregnant women presented with subgroups (males and females), the number of measurements (n), mean, standard deviation (SD), 95% confidence interval of the mean (95% CI), and p-value (p) for the between-group tests.

From: Maternal physical activity affects yolk sac size and growth in early pregnancy, but girls and boys use different strategies

Term

Sex

n

Mean

SD

95% CI

p*

Week 7: 1st measurement; GA (weeks)

 

180

7.6

0.7

(7.5–7.7)

 
 

89

7.5

0.5

(7.4–7.6)

0.08

 

91

7.7

0.9

(7.5–7.8)

Week 7: 1st yolk sac diameter (mm)

 

180

4.7

0.6

(4.7–4.8)

 
 

89

4.7

0.6

(4.6–4.8)

0.39

 

91

4.8

0.6

(4.7–4.9)

Week 10: 2nd measurement; GA (weeks)

 

178

10.6

0.8

(10.5–10.7)

 
 

87

10.6

0.7

(10.5–10.8)

0.65

 

91

10.7

0.9

(10.5–10.9)

Week 10: 2nd yolk sac diameter (mm)

 

178

5.9

0.9

(5.8–6.0)

 
 

87

5.9

0.8

(5.7–6.1)

0.99

 

91

5.9

1.0

(5.7–6.1)

Week 7–10: Yolk sac growth rate (mm week−1)

 

170

0.38

0.33

(0.33–0.43)

 
 

81

0.37

0.29

(0.30–0.43)

0.67

 

89

0.39

0.36

(0.32–0.46)

  1. Gestational age (GA) was based on the last menstrual period.
  2. *The unpaired t test was performed for the yolk sac data, and the Mann‒Whitney U test (Wilcoxon rank-sum test) was performed for the gestational age data.