Maternal Smoking and the Risk of Placenta Accreta Spectrum: A Systematic Review and Meta-Analysis

Table 2

Results of subgroup analysis of the maternal smoking and placenta accreta spectrum based on study design and adjust/crude form for control of the counfounding variables.

Subgroups	No. of studies	OR (95% CI)
Study design
Case-control	4	0.83 (0.47, 1.19)	0.0%
Cohort	10	1.35 (1.15, 1.55)	0.0%
Adjust/crude form
Adjust analysis	6	1.11 (0.74, 1.49)	32.1%
Crude analysis	8	1.29 (1.0, 1.58)	0.0%