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Table 1 Risk factors for included meta-analysis in the present umbrella review

From: The environmental risk factors prior to conception associated with placental abruption: an umbrella review

Risk factors

Source (year)

Number of population

Number of included studies

Study design

Effect metrics

Random effect summary estimate

Credibility of evidence

AMSTAR2 quality

Maternal asthma

Wang, 2014

1,377,063

11

Cohort

Relative risk

1.29 (1.14, 1.47)

Suggestive

Critically low

Maternal pre-pregnancy BMI

Underweight

Overweight

Obese

Adane, 2019

114,792

9

Cohort/case-control

Odds ratio

1.38 (1.12, 1.70)

0.84 (0.76, 0.93)

0.77 (0.68, 0.87)

Weak

Weak

Suggestive

Critically low

Prior cesarean section

Klar, 2014

5,454,621

8

Cohort/case-control

Relative risk

1.38 (1.35, 1.42)

Suggestive

Critically low

Cocaine use

Addis, 2001

21,881

13

Cohort/case-control

Relative risk

4.55 (3.19, 6.50)

Suggestive

Low

Endometriosis

Breintoft, 2021

7,320,658

8

Cohort

Odds ratio

1.40 (1.12, 1.76)

Suggestive

Critically low

Fetal sex

Broere-Brown, 2020

3,130,530

13

Cohort/case-control

Odds ratio

1.07 (0.93, 1.23)

NS

Critically low

Chronic hypertension

Ananth, 1996

517,382

8

Cohort/case-control

Odds ratio

3.13 (2.04, 4.80)

Suggestive

Critically low

preeclampsia

Ananth,1996

660,979

12

Cohort/case-control

Odds ratio

1.73 (1.47, 2.04)

Weak

Critically low

Uterine leiomyoma

Jenabi, 2017

232,024

9

Cohort/case-control

Odds ratio

2.63 (1.38, 3.88)

Weak

Critically low

Marijuana use

Conner, 2016

22,863

5

Cohort/case-control

Odds ratio

1.78 (1.32, 2.40)

Weak

Critically low

Advanced maternal age

Martinelli, 2018

20,684,077

14

Cohort

Odds ratio

1.44 (1.35, 1.54)

Suggestive

Critically low

Maternal smoking

Shobeiri, 2017

4,309,610

27

Cohort/case-control

Odds ratio

Relative risk

1.80 (1.75, 1.85)

1.65 (1.51, 1.80)

Suggestive

Critically low

Use of ART

Vermey, 2019

1,158,943

14

Cohort

Odds ratio

1.87 (1.70, 2.06)

Suggestive

Critically low

  1. ART assisted reproductive techniques