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Table 1 Maternal characteristics and rate of placenta previa (per 1000 births) in second births

From: Risk of placenta previa in second birth after first birth cesarean section: a population-based study and meta-analysis

 

Number (%) of births

Placenta Previa Rate

Unadjusted OR

(95% CI)**

Adjusted OR

(95% CI)**

Previous cesarean delivery

  

p < 0.001

p < 0.001

   Yes

86055 (21.5)

8.7

1.88 (1.71-2.07)

1.60 (1.44-1.76)

   No

313619 (78.5)

4.4

-

-

Previous placenta previa

  

p < 0.001

p < 0.001

   Yes

1429 (0.4)

43.4

7.74 (5.80-10.34)

4.77 (3.55-6.42)

   No

398245 (99.6)

5.2

-

-

Maternal age*

  

p < 0.001

p < 0.001

   <20

15393 (3.9)

1.9

0.56 (0.38-0.82)

0.58 (0.39-0.86)

   20-29

191151 (47.8)

3.6

-

-

   30-39

184237 (46.1)

7.1

2.01 (1.82-2.22)

1.83 (1.65-2.05)

   ≥40

8887 (2.2)

13.2

3.60 (2.90-4.46)

3.01 (2.41-3.75)

Ethnicity*

  

p = 0.053

p = 0.387

   White

275181 (80.4)

5.6

-

-

   Asian

42486 (12.4)

4.8

0.86 (0.74-0.99)

1.03 (0.89-1.21)

   Black

12158 (3.6)

5.0

0.91 (0.70-1.17)

0.96 (0.74-1.25)

   Other

12448 (3.6)

6.7

1.19 (0.96-1.50)

1.22 (0.97-1.52)

Deprivation*

  

p < 0.001

p = 0.180

   Q1 Most deprived

122039 (30.6)

4.0

-

-

   Q2

90740 (22.8)

5.1

1.30 (1.14-1.49)

1.10 (0.96-1.26)

   Q3

85913 (21.6)

6.1

1.52 (1.33-1.73)

1.15 (0.99-1.32)

   Q4 Least deprived

99403 (25.0)

6.5

1.63 (1.44-1.85)

1.16 (1.01-1.33)

Pre-existing hypertension

  

p = 0.080

p = 0.026

   Yes

5730 (1.4)

3.5

0.69 (0.44-1.08)

0.62 (0.39-0.98)

   No

393944 (98.6)

5.4

-

-

Gestational hypertension***

  

p = 0.322

p = 0.098

   Yes

8464 (2.1)

5.1

0.85 (0.60-1.19)

0.76 (0.54-1.07)

   No

391210 (97.9)

5.3

-

-

Gestational diabetes

  

p = 0.337

p = 0.892

   Yes

5586 (1.4)

5.9

1.19 (0.84-1.69)

0.98 (0.69-1.39)

   No

394088 (98.6)

5.3

-

-

Polyhydramnios

  

p = 0.003

p = 0.009

   Yes

1985 (0.5)

11.1

2.11 (1.35-3.28)

1.92 (1.23-3.00)

   No

397689 (99.5)

5.3

-

-

Inter-birth interval

  

p < 0.001

p < 0.001

   <1

7511 (1.9)

6.4

1.38 (1.02-1.87)

2.08 (1.53-2.83)

   1 to 2

120803 (30.2)

4.8

0.92 (0.81-1.03)

1.01 (0.90-1.14)

   2 to 3

133834 (33.5)

5.2

-

-

   3 to 4

73992 (18.5)

5.5

1.08 (0.95-1.23)

1.08 (0.94-1.23)

   4 to 5

35557 (8.9)

6.1

1.19 (1.01-1.40)

1.19 (1.01-1.40)

   ≥5

27977 (7.0)

6.6

1.29 (1.09-1.53)

1.32 (1.11-1.57)

  1. * Not including missing values (Maternal age n = 6, 0.0%; Deprivation n = 1549, 0.4%; Ethnicity n = 57401, 14.6% of data missing)
  2. ** The model was adjusted for all the variables presented in the table. P-values from the likelihood ratio test
  3. *** Gestational hypertension includes pre-eclampsia and eclampsia
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BMC Pregnancy and Childbirth

ISSN: 1471-2393

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