The association between maternal smoking and placenta abruption: a meta-analysis.
BACKGROUND
Several epidemiological studies have determined that maternal smoking can increase the risk of placenta abruption. To date, only a meta-analysis has been performed for assessing the relationship between smoking and placenta abruption. This meta-analysis was conducted to estimate the association between smoking and the risk of placenta abruption.


METHODS
A literature search was conducted in major databases such as PubMed, Web of Science, and Scopus from the earliest possible year to April 2016. The heterogeneity across studies was explored by Q-test and I2statistic. The publication bias was assessed using Begg's and Egger's tests. The results were reported using odds ratio (OR) estimate with its 95% confidence intervals (CI) using a random effects model.


RESULTS
The literature search yielded 1167 publications until April 2016 with 4 309 610 participants. Based on OR estimates obtained from case-control and cohort studies, there was a significant association between smoking and placenta abruption (1.80; 95% CI: 1.75, 1.85). Based on the results of cohort studies, smoking and placenta abruption had a significant association (relative risk ratio: 1.65; 95% CI: 1.51, 1.80).


CONCLUSIONS
Based on reports in epidemiological studies, we showed that smoking is a risk factor for placenta abruption.
a Mother and Child Care Research Center , Hamadan University of Medical Sciences , Hamadan , Iran and.
Fatemeh
F
Shobeiri
a Mother and Child Care Research Center , Hamadan University of Medical Sciences , Hamadan , Iran and.
Seyedeh Zahra
SZ
Masoumi
b Department of Midwifery , Toyserkan Branch, Islamic Azad University , Toyserkan , Iran.
Ensiyeh
E
Jenabi
D000037:Abruptio Placentae / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D011247:Pregnancy; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology
Placenta abruption; meta-analysis; pregnancy; smoking