Table 2 Univariate and multivariate analysis to investigate the risk factor of retained products of conception in pregnant women with placenta previa

Maternal age

  > 35 years vs < 35 years

1.68

(0.73–3.92)

0.22

Gestational age at delivery

  > 37 weeks vs < 37 weeks

1.27

(0.55–2.95)

0.58

Parity

 Primipara vs Multipara

0.57

(0.24–1.33)

0.19

In vitro fertilization pregnancy

 Yes vs. No

1.84

(0.65–5.20)

0.25

Tocolytic agent use

 Yes vs. No

2.08

(0.90–4.84)

0.09

Warning bleeding^a

 Yes vs. No

2.21

(0.96–5.13)

0.06

Prior cesarean section

 Yes vs. No

7.13

(2.96–17.19)

 < 0.01

10.70

(3.47–33.00)

 < 0.01

The mode of cesarean section

 Emergency vs Elective

1.21

(0.46–3.18)

0.69

The classification of placenta previa

 Major previa^b vs Minor previa^c

3.86

(1.49–9.99)

 < 0.01

1.72

(0.55–5.42)

0.35

Main location of placenta

 Anterior wall vs Posterior wall

2.72

(1.01–7.32)

0.048

1.38

(0.37–5.7)

0.63

Placenta accreta spectrum

 Yes vs. No

92.7

(18.39–467.22)

 < 0.01

140.32

(23.84–825.79)

 < 0.01

Prior endometrial curettage

 Yes vs. No

1.37

(0.57–3.33)

0.48