Study ID
|
Country
|
No. of PABC cases
|
No. of controls
|
PABC definition
|
Cancer stage or grade
|
Mean/median age of PABC
|
Follow-up years
|
Outcomes measured
|
HR estimate
|
HR
|
95% CI
|
NOS score
|
Matching criteria
|
Adjusting variable
|
Mausner, 1969 [22]
|
USA
|
73
|
647
|
Pregnancy & <6 months postpartum
|
Stage Ⅰ Ⅱ Ⅲ, Grade Ⅰ Ⅱ Ⅲ
|
35
|
5
|
OS
|
indirect
|
1.36
|
1.07-1.73
|
7
|
-
|
-
|
Wallgren, 1977[23]
|
Sweden
|
15
|
58
|
Pregnancy & <12 months postpartum
|
Grade Ⅰ Ⅱ Ⅲ
|
<30
|
10
|
OS
|
indirect
|
1.35
|
0.71-2.58
|
7
|
-
|
-
|
Nugent, 1985[24]
|
USA
|
19
|
155
|
Pregnancy
|
Stage Ⅰ Ⅱ Ⅲ
|
32
|
5
|
OS
|
indirect
|
0.96
|
0.55-1.67
|
6
|
-
|
-
|
Tretli, 1988-Pregnancy[25]
|
Norway
|
20
|
40
|
Pregnancy
|
Stage Ⅰ Ⅱ Ⅲ
|
33
|
4
|
OS
|
indirect
|
2.41
|
1.32-4.37
|
6
|
Diagnosed year, diagnosed age
|
-
|
Tretli, 1988-Postpartum[25]
|
Norway
|
15
|
40
|
Unspecified
|
Stage Ⅰ Ⅱ Ⅲ
|
36
|
4
|
OS
|
indirect
|
1.47
|
0.66-3.27
|
6
|
-
|
Greene, 1988[26]
|
USA
|
8
|
36
|
Pregnancy
|
NA
|
<35
|
14
|
OS
|
indirect
|
1.50
|
0.18-12.62
|
6
|
-
|
-
|
Petrek, 1991[27]
|
USA
|
56
|
166
|
Pregnancy & <12 months postpartum
|
NA
|
-
|
5
|
OS
|
paper
|
0.74
|
0.37-1.45
|
6
|
-
|
Node status
|
Zemlickis, 1992[28]
|
Canada
|
102
|
269
|
Pregnancy & postpartum (unspecified)
|
Stage 0 Ⅰ Ⅱ Ⅲ Ⅳ
|
33
|
25
|
CSS
|
indirect
|
1.25
|
0.93-1.69
|
8
|
Stage, age at diagnosis
|
-
|
Ishida, 1992 [29]
|
Japan
|
192
|
191
|
Pregnancy & <24 months postpartum
|
Stage 0 Tis Ⅰ Ⅱ Ⅲ Ⅳ
|
32
|
10
|
OS
|
indirect
|
2.00
|
1.27-3.16
|
6
|
-
|
|
Guinee, 1994-Pregnancy[30]
|
USA
|
26
|
139
|
Pregnancy
|
NA
|
28(20-29)
|
10
|
OS
|
paper
|
2.83
|
1.24-6.45
|
8
|
-
|
Tumour size, number of positive axillary nodes
|
Guinee, 1994-Postpartum [30]
|
USA
|
40
|
139
|
<12 Months postpartum
|
NA
|
28(20-29)
|
10
|
OS
|
paper
|
1.88
|
0.88-3.98
|
8
|
-
|
Von Schoultz, 1995 [31]
|
Sweden
|
173
|
1740
|
Pregnancy & <60 months postpartum
|
NA
|
<50
|
7
|
DFS
|
paper
|
1.02
|
0.72-1.43
|
9
|
-
|
Age, nodal status, tumour size, ER status
|
Ezzat, 1996-OS[32]
|
Saudi Arabia
|
28
|
84
|
Pregnancy
|
Stage Ⅰ Ⅱ Ⅲ
|
20-45
|
7
|
OS
|
paper
|
0.90
|
0.6-1.3
|
6
|
Year of diagnosis, date of beginning
|
-
|
Ezzat, 1996-DFS[32]
|
Saudi Arabia
|
28
|
84
|
Pregnancy
|
Stage Ⅰ Ⅱ Ⅲ
|
20-45
|
7
|
DFS
|
paper
|
1.10
|
0.8-1.5
|
6
|
-
|
Anderson, 1996-OS[33]
|
USA
|
22
|
205
|
Pregnancy & <12 months postpartum
|
Stage 0 Ⅰ Ⅱ Ⅲa
|
<30
|
10
|
OS
|
paper
|
2.40
|
1.28-4.50
|
8
|
-
|
Stage, axillary LN involvement, adjuvant CT, tumour size
|
Anderson, 1996-DFS[33]
|
USA
|
22
|
205
|
Stage 0 Ⅰ Ⅱ Ⅲa
|
<30
|
10
|
DFS
|
indirect
|
3.19
|
1.20-8.49
|
8
|
-
|
Bonnier, 1997-OS[34]
|
France
|
154
|
308
|
Pregnancy & <6 months postpartum
|
Grade Ⅰ Ⅱ Ⅲ
|
33.9(23.2-46.4)
|
5
|
OS
|
paper
|
1.46
|
0.72-2.96
|
6
|
-
|
Clinical tumour size, microscopic lymph-node involvement, inflammatory cancer, age
|
Bonnier, 1997-DFS[34]
|
France
|
154
|
308
|
Grade Ⅰ Ⅱ Ⅲ
|
5
|
DFS
|
paper
|
1.48
|
1.00-2.19
|
6
|
-
|
Olson, 1998[35]
|
USA
|
146
|
-
|
-
|
NA
|
<45
|
15
|
OS
|
paper
|
-
|
-
|
7
|
-
|
Age, tumour size, lymph nodes, ER status, histology
|
Reeves, 2000[36]
|
UK
|
-
|
-
|
-
|
Stage Ⅰ Ⅱ Ⅲ Ⅳ
|
<60
|
>10
|
OS
|
paper
|
-
|
-
|
9
|
-
|
Age at diagnosis, year of diagnosis, hospital, weight in kg
|
Ibrahim, 2000[37]
|
Saudi Arabia
|
72
|
216
|
Pregnancy
|
Stage Ⅰ Ⅱ Ⅲ Ⅳ, Grade Ⅰ Ⅱ Ⅲ
|
34
|
10
|
OS
|
indirect
|
0.94
|
0.62-1.44
|
6
|
Age, stage, year of diagnosis
|
-
|
Daling, 2002[38]
|
USA
|
83
|
309
|
<24 Months postpartum
|
Stage Ⅰ Ⅱ Ⅲ Ⅳ
|
<45
|
5
|
OS
|
indirect
|
2.30
|
1.4-3.9
|
9
|
-
|
Age, diagnosis year
|
Aziz, 2003[39]
|
Pakistan
|
24
|
48
|
Pregnancy & <12 months postpartum
|
NA
|
32(20-45)
|
7
|
OS
|
indirect
|
1.67
|
0.82-3.41
|
6
|
Age, tumour grade, tumour size, axillary lymph node status
|
-
|
Siegelmann-Danieli, 2003-OS[40]
|
Israel
|
22
|
192
|
Pregnancy & <12 months postpartum
|
NA
|
33(25-27)
|
5
|
OS
|
indirect
|
3.39
|
0.58-19.81
|
6
|
-
|
-
|
Siegelmann-Danieli, 2003-DFS[40]
|
Israel
|
20
|
181
|
NA
|
33(25-28)
|
5
|
DFS
|
indirect
|
4.81
|
1.46-15.9
|
6
|
-
|
-
|
Bladstrom, 2003[41]
|
Sweden
|
94
|
14599
|
Pregnancy
|
NA
|
≤45
|
5
|
OS
|
paper
|
2.40
|
2.0-2.9
|
9
|
-
|
Age, time of diagnosis, time period interaction, number of children, age at first child’s birth
|
Bladstrom, 2003(2)[41]
|
Sweden
|
94
|
14599
|
Pregnancy
|
NA
|
≤45
|
10
|
OS
|
paper
|
1.20
|
0.9-1.7
|
9
|
-
|
Whiteman, 2004[42]
|
USA
|
59
|
355
|
<12 Months postpartum
|
NA
|
20-45
|
15
|
OS
|
paper
|
1.51
|
1.02-2.23
|
9
|
-
|
Surgery, radiation therapy, race, oral contraceptive use, education, BMI, stage history of breast disease
|
Rodriguez, 2008[43]
|
USA
|
797
|
4177
|
Pregnancy & <12 months postpartum
|
Stage Ⅰ Ⅱ Ⅲ Ⅳ
|
<55
|
13
|
OS
|
paper
|
1.14
|
1.00-1.29
|
9
|
-
|
Race, tumour size, AJCC stage, surgery, hormone receptor
|
Stensheim, 2009-Pregnancy[44]
|
Norway
|
59
|
13106
|
Pregnancy
|
NA
|
<50
|
5
|
CSS
|
paper
|
1.23
|
0.82-1.81
|
7
|
-
|
Age, diagnostic period, initial extent of disease
|
Stensheim, 2009-Postpartum[44]
|
Norway
|
46
|
13106
|
<6 Months postpartum
|
NA
|
<50
|
5
|
CSS
|
paper
|
1.95
|
1.36-2.78
|
7
|
-
|
Beadle, 2009-OS[45]
|
USA
|
104
|
564
|
Pregnancy & <12 months postpartum
|
Stage Ⅰ Ⅱ Ⅲ
|
≤35
|
10
|
OS
|
indirect
|
1.24
|
0.87-1.79
|
6
|
-
|
-
|
Beadle, 2009-DFS (distant metastasis) [45]
|
USA
|
104
|
564
|
Pregnancy & <12 months postpartum
|
Stage Ⅰ Ⅱ Ⅲ
|
≤35
|
10
|
DFS
|
indirect
|
1.35
|
0.98-1.85
|
6
|
-
|
-
|
Beadle, 2009-DFS (locoregional recurrence) [45]
|
USA
|
104
|
564
|
Stage Ⅰ Ⅱ Ⅲ
|
≤35
|
10
|
DFS
|
indirect
|
1.44
|
0.78-2.66
|
6
|
-
|
-
|
Halaska, 2009-OS[46]
|
Greece
|
32
|
32
|
Pregnancy & <12 months postpartum
|
Grade Ⅰ Ⅱ Ⅲ
|
<45
|
10
|
OS
|
indirect
|
1.42
|
0.58-3.48
|
6
|
Age at diagnosis, tumour size, axillary lymph node status, presence or absence of metastatic deposits
|
-
|
Halaska, 2009-DFS[46]
|
Greece
|
32
|
32
|
Grade Ⅰ Ⅱ Ⅲ
|
<45
|
10
|
DFS
|
indirect
|
1.82
|
0.82-4.05
|
6
|
-
|
Largillier, 2009-OS[47]
|
France
|
105
|
788
|
Pregnancy & <12 months postpartum
|
Grade Ⅰ Ⅱ Ⅲ
|
<35
|
10
|
OS
|
paper
|
1.51
|
1.05-2.20
|
7
|
-
|
-
|
Largillier, 2009-DFS[47]
|
France
|
105
|
788
|
Grade Ⅰ Ⅱ Ⅲ
|
<35
|
10
|
DFS
|
paper
|
1.25
|
0.90-1.74
|
7
|
-
|
-
|
Phillips, 2009[48]
|
Multicentre
|
676
|
-
|
-
|
NA
|
-
|
10
|
OS
|
paper
|
-
|
-
|
8
|
-
|
Study centre, education, BMI, time since last full-term pregnancy, age at diagnosis
|
Moreira, 2010[49]
|
Brazil
|
87
|
252
|
Pregnancy & <12 months postpartum
|
NA
|
≤ 45
|
10
|
OS
|
paper
|
1.52
|
1.10-2.10
|
7
|
Registration institution, age, registration year
|
-
|
Johansson, 2011[50]
|
Sweden
|
1110
|
14611
|
Pregnancy & <24 months postpartum
|
NA
|
15-44
|
15
|
OS
|
paper
|
1.51
|
1.36-1.68
|
7
|
-
|
Age, calendar time, education
|
Murphy, 2012[51]
|
USA
|
99
|
186
|
Pregnancy & <12 months postpartum
|
Grade 0 Ⅰ Ⅱ Ⅲ
|
35(24-48)
|
18
|
OS
|
paper
|
0.59
|
0.29-1.17
|
7
|
Age, year of diagnosis
|
Tumour grade, ER status, LN involvement
|
Azim, 2012-OS [52]
|
Italy
|
65
|
130
|
Pregnancy
|
NA
|
<50
|
6
|
OS
|
paper
|
1.70
|
0.80-3.90
|
7
|
Age, year of surgery, pathological tumour size, pathological nodal status
|
pN, neoadjuvant chemotherapy, ER
|
Azim, 2012-DFS [52]
|
Italy
|
65
|
130
|
Pregnancy
|
NA
|
<50
|
6
|
DFS
|
paper
|
2.30
|
1.30-4.20
|
7
|
Age, pT, pN, neoadjuvant chemotherapy, Ki-67, HER2, perivascular invasion
|
Ali, 2012-OS[53]
|
USA
|
40
|
40
|
Pregnancy & <12 months postpartum
|
Stage Ⅰ Ⅱ Ⅲ Ⅳ
|
33(24-42)
|
16
|
OS
|
indirect
|
2.15
|
1.13-4.09
|
7
|
-
|
Age and stage-matched
|
Ali, 2012-DFS[53]
|
USA
|
40
|
40
|
Stage Ⅰ Ⅱ Ⅲ Ⅳ
|
33(24-42)
|
16
|
DFS
|
indirect
|
2.00
|
1.12-3.59
|
7
|
-
|
Amant, 2013-OS[54]
|
Belgium
|
311
|
865
|
Pregnancy
|
Stage Ⅰ Ⅱ Ⅲ, Grade Ⅰ Ⅱ Ⅲ
|
33(31-36)
|
5
|
OS
|
paper
|
1.19
|
0.73-1.93
|
8
|
-
|
Age at diagnosis, stage, grading, histologic tumour type, ER/PR status, HER2, chemotherapy
|
Amant, 2013-DFS[54]
|
Belgium
|
311
|
865
|
Pregnancy
|
Stage Ⅰ Ⅱ Ⅲ, Grade Ⅰ Ⅱ Ⅲ
|
33(31-36)
|
5
|
DFS
|
paper
|
1.34
|
0.93-1.91
|
8
|
-
|
Litton, 2013-OS[55]
|
USA
|
75
|
150
|
Pregnancy
|
Stage Ⅰ Ⅱ Ⅲ
|
24-45
|
5
|
OS
|
paper
|
1.87
|
1.04-3.36
|
7
|
Age at diagnosis, stage at diagnosis, year of diagnosis
|
Age at diagnosis, year of diagnosis, clinical cancer stage, tumour nuclear grade
|
Litton, 2013-DFS[55]
|
USA
|
75
|
150
|
Pregnancy
|
Stage Ⅰ Ⅱ Ⅲ
|
24-45
|
5
|
DFS
|
paper
|
2.09
|
1.19-3.67
|
7
|
Valentini, 2013[56]
|
USA
|
75
|
269
|
Pregnancy & <12 months postpartum
|
NA
|
32.5(20-45)
|
15
|
OS
|
paper
|
0.79
|
0.25-2.44
|
7
|
-
|
Age at diagnosis, tumour size, lymph node status, ER status, use of chemotherapy, oophorectomy
|
Dimitrakakis, 2013[57]
|
Greece
|
39
|
39
|
Pregnancy & <12 months postpartum
|
Stage Ⅰ Ⅱ Ⅲ Ⅳ, Grade Ⅰ Ⅱ Ⅲ
|
34.3 ± 5.0
|
5
|
OS
|
paper
|
9.28
|
2.94-29.27
|
6
|
Stage, age, year of diagnosis
|
Stage, ER status, grade, age at diagnosis
|
Calliha, 2013-OS[58]
|
USA
|
76
|
86
|
Pregnancy & <60 months postpartum
|
Stage 0 Ⅰ Ⅱ Ⅲ Ⅳ, Grade Ⅰ Ⅱ Ⅲ
|
≤45
|
5
|
OS
|
paper
|
2.65
|
1.09-6.42
|
6
|
-
|
Tumour biological subtype, clinical stage, year of diagnosis
|
Calliha, 2013-DFS[58]
|
USA
|
74
|
84
|
Pregnancy & <60 months postpartum
|
Stage 0 Ⅰ Ⅱ Ⅲ Ⅳ, Grade Ⅰ Ⅱ Ⅲ
|
≤45
|
5
|
DFS
|
paper
|
2.80
|
1.12-6.57
|
6
|
-
|
Tumour biological subtype, clinical stage, year of diagnosis, local recurrence
|
Bell, 2013-OS[59]
|
Australia
|
13
|
377
|
Pregnancy & <12 months postpartum
|
NA
|
<48
|
5
|
OS
|
paper
|
2.50
|
0.5-11.7
|
6
|
-
|
-
|
Bell, 2013-DFS[59]
|
Australia
|
13
|
377
|
Pregnancy & <12 months postpartum
|
NA
|
<48
|
5
|
DFS
|
paper
|
0.90
|
0.2-4.4
|
6
|
-
|
-
|
Moller, 2013[60]
|
UK
|
-
|
-
|
-
|
Stage Ⅰ Ⅱ Ⅲ Ⅳ
|
10-54
|
10
|
OS
|
paper
|
-
|
-
|
7
|
-
|
Age, stage
|
Framarino-dei-Malatesta, 2014[61]
|
Italy
|
22
|
45
|
Pregnancy
|
NA
|
37.2±3.2
|
10
|
OS
|
indirect
|
0.96
|
0.29-3.21
|
6
|
Age
|
-
|
Madaras, 2014[62]
|
Hungary
|
31
|
31
|
Pregnancy & <12 months postpartum
|
-
|
34
|
10
|
OS
|
indirect
|
5.76
|
2.09-15.98
|
7
|
Age, year of first breast cancer diagnosis
|
-
|
Nagatsuma, 2014[63]
|
Japan
|
-
|
-
|
-
|
Stage 0 Ⅰ Ⅱ Ⅲ Ⅳ, Grade Ⅰ Ⅱ Ⅲ
|
26-44
|
10
|
OS
|
paper
|
-
|
-
|
7
|
-
|
Age at diagnosis, AJCC clinical stage, histological tumour grade, oestrogen and progesterone receptor status, HER2 status
|
Strasser-Weippl, 2014[64]
|
China
|
109
|
1274
|
Pregnancy & <60 months postpartum
|
Grade Ⅰ Ⅱ Ⅲ
|
<45
|
5
|
DFS
|
paper
|
1.62
|
1.04-2.54
|
8
|
-
|
Age, oestrogen receptor, progesterone receptor, HER2 status, disease stage
|
Genin, 2015-OS[65]
|
France
|
87
|
174
|
Pregnancy & <12 months postpartum
|
Grade Ⅰ Ⅱ Ⅲ
|
35(27-40)
|
10
|
OS
|
indirect
|
1.09
|
0.79-1.52
|
7
|
Age, year of diagnosis
|
-
|
Genin, 2015-DFS[65]
|
France
|
87
|
174
|
Pregnancy & <12 months postpartum
|
Grade Ⅰ Ⅱ Ⅲ
|
35(27-40)
|
10
|
DFS
|
paper
|
1.87
|
1.05-3.33
|
7
|
Age, year of diagnosis
|
Age, ER, HR status, tumour stage, HER2 status, Ki-67 rate
|
Iqbal, 2017[14]
|
Canada
|
501
|
5832
|
Pregnancy & <21 months postpartum
|
Stage Ⅰ Ⅱ Ⅲ Ⅳ
|
20-45
|
5
|
OS
|
paper
|
1.11
|
0.86-1.45
|
9
|
-
|
Year of diagnosis, age, tumour size, nodal status, oestrogen receptor status, progesterone receptor status, chemotherapy, radiotherapy, et al
|
Kim, 2017[66]
|
Korea
|
344
|
668
|
Pregnancy & <12 months postpartum
|
Stage 0 Ⅰ Ⅱ Ⅲ Ⅳ, Grade Ⅰ Ⅱ Ⅲ
|
20-45
|
10
|
OS
|
indirect
|
1.85
|
1.28-2.67
|
8
|
Operation period, age, initial stage
|
-
|
Bae, 2018(1)[67]
|
Korea
|
40
|
2770
|
Pregnancy & <12 months postpartum
|
Stage 0 Ⅰ Ⅱ Ⅲ
|
33.5 (27– 40)
|
5
|
CSS
|
paper
|
4.00
|
1.20-12.90
|
8
|
-
|
Age, stage, chemotherapy
|
Bae, 2018(2)[68]
|
Korea
|
411
|
83381
|
Pregnancy & <12 months postpartum
|
Stage 0 Ⅰ Ⅱ Ⅲ Ⅳ
|
20-49
|
15
|
OS
|
paper
|
1.03
|
0.74-1.42
|
9
|
-
|
Age at diagnosis, stage, high versus low/intermediate, luminal subtype, HER2 subtype, et al
|
Boudy, 2018-DFS[16]
|
France
|
49
|
51
|
Pregnancy
|
Grade Ⅰ Ⅱ Ⅲ
|
<46
|
5
|
DFS
|
indirect
|
1.19
|
0.75-1.91
|
8
|
Propensity score
|
-
|
Boudy, 2018-CSS[16]
|
France
|
49
|
51
|
Pregnancy
|
Grade Ⅰ Ⅱ Ⅲ
|
<46
|
5
|
CSS
|
indirect
|
1.06
|
0.65-1.72
|
8
|
-
|
Johansson, 2018[2]
|
Sweden
|
778
|
1661
|
Pregnancy & <24 months postpartum
|
Stage 0 Ⅰ Ⅱ Ⅲ Ⅳ
|
15-44
|
10
|
OS
|
indirect
|
0.90
|
0.55-1.40
|
9
|
-
|
Age, period, education, region, tumour characteristics, pathologic T stage, N stage, ER/PR
|
Chuang, 2018[69]
|
China (Taiwan)
|
-
|
-
|
-
|
Stage Ⅰ Ⅱ Ⅲ
|
20-50
|
>10
|
OS
|
paper
|
-
|
-
|
9
|
-
|
Age and year of diagnosis, stage, tumour size, positive lymph nodes, histological grading, treatments
|
Ploquin, 2018-OS[15]
|
France
|
111
|
253
|
Pregnancy
|
Stage 0 Ⅰ Ⅱ Ⅲ Ⅳ
|
22-46
|
5
|
OS
|
paper
|
1.10
|
0.67-1.79
|
8
|
Age, clinical T stage, hormone receptor
|
Clinical nodal status, age
|
Ploquin, 2018-DFS[15]
|
France
|
111
|
253
|
Pregnancy
|
Stage 0 Ⅰ Ⅱ Ⅲ Ⅳ
|
22-46
|
5
|
DFS
|
paper
|
1.15
|
0.78-1.68
|
8
|
Suleman, 2019-OS[70]
|
Saudi Arabia
|
110
|
114
|
Pregnancy
|
Stage Ⅰ Ⅱ Ⅲ Ⅳ
|
20-48
|
>10
|
OS
|
indirect
|
2.58
|
1.26-5.26
|
7
|
Diagnosed year
|
-
|
Suleman, 2019-DFS[70]
|
Saudi Arabia
|
110
|
114
|
Pregnancy
|
Stage Ⅰ Ⅱ Ⅲ Ⅳ
|
20-48
|
>10
|
DFS
|
indirect
|
1.18
|
0.70-1.97
|
7
|
-
|
Choi, 2019[17]
|
Korea
|
63
|
3804
|
Pregnancy & <12 months postpartum
|
NA
|
<50
|
10
|
OS
|
paper
|
1.52
|
0.82-2.83
|
8
|
-
|
Histologic type, stage, ER, PR, age at diagnosis, Charlson comorbidity index
|