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Table 2 Associations of exposure to the COVID-19 lockdown with gestational length

From: Associations of COVID-19 lockdown with gestational length and preterm birth in China

 

No. of participants

Gestational length (week, Mean ± SD)

Mean difference in gestational length (week)

Unexposed group

Exposed group b

Unexposed group

Exposed group b

Crude β (95% CI)

Adjusted β (95% CI) *

Gestational week at the beginning of the Level I lockdown

 All

493,496

101,900

38.74 ± 1.46

38.66 ± 1.46

−0.08 (−0.09, −0.07)

−0.06 (−0.07, −0.05)

 Conception during the lockdown

64,645

11,317

38.72 ± 1.52

38.64 ± 1.49

−0.08 (− 0.11, − 0.05)

−0.04 (− 0.07, − 0.01)

 Prior to 4th

53,300

10,937

38.71 ± 1.50

38.64 ± 1.50

−0.07 (− 0.10, − 0.04)

− 0.10 (− 0.14, − 0.07)

 4th -7th

50,973

10,494

38.67 ± 1.52

38.52 ± 1.54

− 0.14 (− 0.17, − 0.11)

− 0.13 (− 0.16, − 0.09)

 8th -11th

48,926

10,237

38.70 ± 1.50

38.58 ± 1.54

−0.12 (− 0.15, − 0.08)

−0.10 (− 0.13, − 0.07)

 12th -15th

46,255

9844

38.73 ± 1.51

38.61 ± 1.55

−0.11 (− 0.15, − 0.08)

−0.11 (− 0.14, − 0.07)

 16th -19th

45,913

9539

38.74 ± 1.48

38.63 ± 1.52

−0.11 (− 0.14, − 0.08)

−0.10 (− 0.13, − 0.06)

 20th -23rd

41,017

8830

38.74 ± 1.49

38.64 ± 1.52

−0.10 (− 0.14, − 0.07)

−0.10 (− 0.13, − 0.06)

 24th -27th

40,358

8750

38.68 ± 1.49

38.66 ± 1.44

−0.02 (− 0.06, 0.01)

−0.01 (− 0.04, 0.03)

 28th -31st

38,146

8101

38.72 ± 1.39

38.63 ± 1.36

−0.09 (− 0.12, − 0.06)

−0.07 (− 0.10, − 0.04)

 32nd -36th

47,382

10,213

38.74 ± 1.21

38.73 ± 1.18

−0.01 (− 0.03, 0.02)

0.02 (− 0.01, 0.04)

 37th - 41st

16,581

3638

39.40 ± 0.92

39.41 ± 0.93

0.01 (−0.02, 0.04)

0.03 (0.01, 0.07)

 

Exposure dose (Mean ± SD)

Gestational length (week, Mean ± SD)

Mean difference in gestational length (week)

Unexposed group

Exposed group

Unexposed group

Exposed group

Crude β (95% CI)

Adjusted β (95% CI) *

Cumulative exposure dose in the first 22 weeks during the Level I to the Level III lockdown a

 Per 100 unit increase in all participants

0 ± 0

195.08 ± 82.21

38.74 ± 1.45

38.61 ± 1.52

−0.06 (−0.07, −0.05)

−0.05 (− 0.06, − 0.04)

Categories of cumulative exposure dose

 Unexposed group

0 ± 0

–

38.74 ± 1.45

–

Reference

Reference

 Q1 (< 132)

–

73.40 ± 38.11

–

38.64 ± 1.52

−0.10 (− 0.13, − 0.08)

−0.09 (− 0.11, − 0.07)

 Q2 (132–225)

–

178.66 ± 27.17

–

38.59 ± 1.54

−0.15 (− 0.17, − 0.12)

−0.13 (− 0.16, − 0.11)

 Q3 (226–263)

–

247.18 ± 10.58

–

38.58 ± 1.51

−0.16 (− 0.18, − 0.13)

−0.14 (− 0.16, − 0.11)

 Q4 (≥264)

–

278.80 ± 8.59

–

38.62 ± 1.51

− 0.12 (− 0.14, − 0.10)*

−0.09 (− 0.11, − 0.07)

 P for trend test

     

<  0.001

  1. In calculating the cumulative exposure dose to lockdown, we assigned a weighting of 3 to days with Level I response, 2 to days with Level II response, 1 to days with Level III response, and 0 to other days
  2. * Adjusted for maternal age, marital status, parity, residential city, delivery type and infant sex
  3. a The exposed group refers to the pregnant women who have experienced the COVID-19 lockdown in their first 22 GWs. The other participants were defined as the unexposed group. The individual cumulative exposure dose was calculated by combining the weightings with the overlap between their pregnancy period ≤22 GWs and the three levels of responses. Q1-Q4 were defined as the cumulative exposure dose of the exposed group classified by quartiles, and the unexposed group was used as reference
  4. b Pregnant women who have experienced the COVID-19 lockdown (from 1/23/2020 to 2/24/2020) during any period of their pregnancy were defined as the exposed group. We further divided the exposed group into subgroups according to their gestational weeks (GW) on 1/23/2020, the beginning of lockdown
  5. -: Not applicable
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BMC Pregnancy and Childbirth

ISSN: 1471-2393

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