Table 4 Crude and adjusted RRs for preterm delivery in different groups.

From: Influent factors of gestational vitamin D deficiency and its relation to an increased risk of preterm delivery in Chinese population

Parameter

Gestational vitamin D status

Sufficiency

Insufficiency

Deficiency

Gestational week (week)

39.3 ± 1.7

39.0 ± 1.5**

38.6 ± 2.5**††

Preterm delivery [n (%)]

25 (2.66)

48 (3.81)

115 (8.23)

Crude RR (95% CI)

1.00

1.45 (0.89, 2.37)

3.28 (2.12, 5.11)**

Adjusted RR (95% CI)1

1.00

2.07 (1.16, 3.71)*

4.02 (2.33, 6.92)**††

Early preterm delivery [n (%)]2

9 (0.97)

6 (0.49)

34 (2.59)

Crude RR (95% CI)

1.00

0.50 (0.18, 1.42)

2.70 (1.29, 5.66)**††

Adjusted RR (95% CI)1

1.00

0.54 (0.19, 1.51)

2.97 (1.41, 6.24)**††

Late preterm delivery [n (%)]2

16 (1.69)

42 (3.32)

81 (5.64)

Crude RR (95% CI)

1.00

1.98 (1.11, 3.55)*

3.62 (2.10, 6.23)**††

Adjusted RR (95% CI)1

1.00

2.09 (1.17, 3.74)*

3.90 (2.26, 6.72)**††

  1. 1Adjusted for pre-pregnancy BMI, maternal age, periconceptional multivitamin use, and season of sampling.
  2. 2Gestational week <32 weeks for early preterm delivery; 32≤ gestational week <37 weeks for late preterm delivery.
  3. *P < 0.05, **P < 0.01 as compared with sufficiency; ††P < 0.01 as compared with insufficiency.
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