Introduction
Materials and methods
Identification of studies
Subject | Search term |
---|---|
Breast neoplasm | Breast neoplasms, subsequent breast neoplasm, breast neoplasm and daughter |
Birth weight | Cirth weight, birthweight, birth size |
Birth order | Birth order, birth rank |
Maternal age | Maternal age, mother's age, parental age |
Gestational age | Gestational age, preterm, prematurity, abruption placenta, pre-eclampsia, eclampsia |
Twinship | Twin, twining, multiple births, multiple pregnancy, monozygote twin, dizygote twin, |
Parental smoking | Maternal smoking, mother's smoking, paternal smoking, father's smoking, parental smoking |
Others | Prenatal factors, perinatal factors, intrauterine environment, intrauterine factor, In-utero exposure |
Statistical analyses
Results
Type of study | Ref. | Year | Design | Cases | Controls (or cohort) | Country/place of study | Birthweight (g) | OR (95% CI) | Comments |
---|---|---|---|---|---|---|---|---|---|
Case-control studies | [42] | 1988 | PCC | 153 | 461 | USA | 1,162–2,948 | Referent | Matched analysis; P for trend = 0.41 |
2,949–3,340 | 0.65 (0.33–1.26) | ||||||||
3,341–4,451 | 0.76 (0.41–1.43) | ||||||||
[12]a | 1992 | LCC | 458 | 1,197 | Sweden | <2,500 | 1.18 (0.60–2.33) | Adjusted for age and birth date | |
2,500–2,999 | Referent | ||||||||
3,000–3,499 | 1.29 (0.90–1.91) | ||||||||
3,500–3,999 | 1.47 (1.00–2.18) | ||||||||
≥ 4,000 | 1.23 (0.80–2.00) | ||||||||
[13] | 1996 | NCC | 550 | 1,478 | USA | <2,500 | 0.56 (0.34–0.93) | Adjusted for age | |
2,500–2,999 | 0.68 (0.47–0.99) | ||||||||
3,000–3,499 | 0.71 (0.50–0.99) | ||||||||
3,500–3,999 | 0.85 (0.59–1.22) | ||||||||
≥ 4,000 | Referent | ||||||||
[14] | 1996 | PCC | 922 | 1,194 | USA | Age 21–45 years: | Adjusted for age, menopausal status, and maternal smoking; P for trend = 0.06 among both groups. The OR (95% CI) for birth weight ≥ 4,000 g among patients with early-onset breast cancer (≤ 30 years old) was 3.3 (1.0–11.0) | ||
<2,500 | 1.3 (0.9–2.0) | ||||||||
2,500–2,999 | Referent | ||||||||
3,000–3,499 | 1.3 (1.0–1.7) | ||||||||
3,500–3,999 | 1.2 (0.8–1.6) | ||||||||
≥ 4,000 | 1.7 (1.1–2.5) | ||||||||
Age 50–64 years: | |||||||||
<2,500 | 0.9 (0.5–1.7) | ||||||||
2,500–2,999 | Referent | ||||||||
3,000–3,499 | 1.1 (0.7–1.7) | ||||||||
3,500–3,999 | 0.8 (0.4–1.3) | ||||||||
≥ 4,000 | 0.6 (0.3–1.1) | ||||||||
[32] | 1997 | NCC | 1068 | 2,027 | Sweden | <2,500 | 0.80 (0.50–1.26) | Adjusted for maternal age, socioeconomic status, parity, and pre-eclampsia or eclampsia, neonatal jaundice, severe prematurity, and twinship | |
2,500–2,999 | Referent | ||||||||
3,000–3,499 | 1.00 (0.79–1.28) | ||||||||
3,500–3,999 | 0.99 (0.77–1.26) | ||||||||
≥ 4,000 | 1.04 (0.77–1.41) | ||||||||
[33] | 1998 | PCC | 510 | 436 | USA | <2,500 | 1.2 (0.7–2.1) | Crude ORs | |
2,500–2,999 | Referent | ||||||||
3,000–3,499 | 1.0 (0.7–1.5) | ||||||||
3,500–3,999 | 1.0 (0.7–1.5) | ||||||||
≥ 4,000 | 1.3 (0.7–2.3) | ||||||||
[15] | 2000 | LCC | 484 | 2,870 | USA | <1,500 | 1.59 (0.61–4.11) | Crude ORs | |
1,500–2,499 | 1.33 (0.94–1.90) | ||||||||
2,500–3,499 | Referent | ||||||||
3,500–4,499 | 1.08 (0.87–1.34) | ||||||||
≥ 4,500 | 3.29 (1.37–7.92) | ||||||||
[34] | 2001 | LTCC | 87 | 87 | Sweden | <1,999 | Referent | Matched analysis by conditional logistic regression | |
2,000–2,499 | 1.6 (0.6–4.0) | ||||||||
2,599–2,999 | 2.4 (0.9–6.2) | ||||||||
≥ 3,000 | 1.6 (0.4–5.6) | ||||||||
(P trend = 0.05) | |||||||||
[43] | 2001 | LCC | 319 | 768 | USA | <2,500 | 1.4 (0.55–3.4) | Crude ORs. Higher birth weight (≥ 3,500 g) carried a marginal significantly higher risk for breast cancer (OR 1.76 [95% CI 0.90–3.35]) relative to lower birth weight (<3,500 g) | |
2,500–3,750 | Referent | ||||||||
≥ 3,750 | 0.9 (0.50–1.6) | ||||||||
[16] | 2001 | LTCC | 90 | 90 | Sweden | ≤ 2,000 | Referent | Crude ORs. Study subjects were women with opposite-sexed pair twins | |
2,001–2,500 | 3.2 (0.8–12.6) | ||||||||
2,501–3,000 | 3.5 (1–13) | ||||||||
3,001–3,500 | 5.8 (1.3–25.7) | ||||||||
≥ 3,501 | 12.1 (1.1–138.8) | ||||||||
[35] | 2002 | PCC | 2,088 | 2,187 | USA | <2,500 | 1.10 (0.90–1.35) | Adjusted for age and residential regions (states) | |
2,500–2,999 | 0.90 (0.70–1.10) | ||||||||
3,000–3,499 | Referent | ||||||||
3,500–3,999 | 1.07 (0.90–1.30) | ||||||||
4,000–4,499 | 0.89 (0.70–1.14) | ||||||||
≥ 4,500 | 1.18 (0.90–1.51) | ||||||||
[44] | 2002 | PCC | 288 | 350 | China | <2,500 | 0.9 (0.4–2.0) | Adjusted for age income, family history of breast cancer in first-degree relative, history of fibroadenoma, age at menarche, parity, and age at first live birth. | |
2,500–2,999 | Referent | ||||||||
3,000–3,499 | 1.1 (0.8–1.6) | ||||||||
3,500–3,999 | 0.8 (0.4–1.4) | ||||||||
≥ 4,000 | 0.7 (0.4–1.4) | ||||||||
[17] | 2002 | LCC | 373 | 1,150 | USA | <3,090 | Referent | Adjusted for parity and age at first birth. P for trend = 0.02 | |
3,090–3,410 | 1.1 (0.8–1.5) | ||||||||
3,420–3,720 | 1.2 (0.9–1.6) | ||||||||
≥ 3,630 | 1.4 (1.1–1.9) | ||||||||
[18] | 2003 | LCC | 881 | 3,423 | Denmark | <2,500 | 1.66 (1.00–2.51) | Adjusted for mother's marital status, maternal age, and birth order | |
2,500–2,999 | 0.83 (0.60–1.10) | ||||||||
3,000–3,499 | Referent | ||||||||
3,500–3,999 | 0.98 (0.80–1.17) | ||||||||
≥ 4,000 | 1.25 (1.00–1.55) | ||||||||
[19] | 2004 | NCC | 89 | 238 | Sweden | 100 g increase | 1.06 (1.00–1.12) | Adjusted for gestational age, birth year, and maternal hypertension/proteinuria | |
[45] | 2004 | LCC | 2471 | 9801 | USA | <1,500 | 0.64 (0.40–1.11) | Adjusted for age and maternal age at first birth | |
1,500–1,999 | 1.05 (0.70–1.68) | ||||||||
2,000–2,499 | 1.02 (0.80–1.31) | ||||||||
2,500–3,499 | Referent | ||||||||
3,500–3,999 | 0.97 (0.90–1.08) | ||||||||
4,000–4,499 | 0.93 (0.80–1.11) | ||||||||
≥ 4,500 | 0.69 (0.40–1.09) | ||||||||
[36] | 2004 | PCC | 196 | 167 | USA | All subjects: | Adjusted for age, race and sampling fractions, body mass index, household income, and maternal age. Tertiles are race specific with cutpoints derived from controls. White women: <3,062, 3,062–3,458, >3,458 g; black women: <3,146, 3,146–3,488, >3,488 g. Restricted data using birth weight measured in pounds and ounces and participant delivered in a medical facility by a physician | ||
Lower tertile | 1.0 (0.6–1.7) | ||||||||
Central tertile | Referent | ||||||||
Upper tertile | 0.7 (0.4–1.2) | ||||||||
White, restricted | |||||||||
data: | |||||||||
Lower tertile | 1.1 (0.5–2.4) | ||||||||
Central tertile | Referent | ||||||||
Upper tertile | 1.4 (0.6–2.0) | ||||||||
[20] | 2006 | PCC | 2,386 | 2,502 | Poland | <2,500 | Referent | Adjusted for: age, education, age at menarche, menopausal status and age at menopause, age at first full-term pregnancy, number of full-term pregnancies, family history of breast cancer among first-degree relatives, mammography screening, and current body mass index. Lower birth weight (<2,500 g) carries greater risk than birth weight of 2,500–4,000 g among women under 45 years old | |
2,500–4,000 | 1.22 (0.92–1.62) | ||||||||
>4,000 | 1.54 (1.08–2.19) | ||||||||
(p-trend = 0.01) | |||||||||
[37] | 2006 | PCC | 1,166 | 2,105 | USA | <2,495 | 1.19 (0.85–1.66) | Adjusted for age (years), education (years), race, body mass index, history of breast benign disease, family history of breast cancer, lactation (months), age at menarche (years), age at first full-term pregnancy (years), age at menopause (years), parity | |
2,495–3,130 | Referent | ||||||||
3,131–3,855 | 0.97 (0.75–1.25) | ||||||||
>3,855 | 1.03 (0.74–1.44) | ||||||||
Cohort studies | [21] | 1999 | LCohort | 57 | 152,590 | Sweden | <2,500 | Referent | Standardization for sex, age, and age-specific incidence rate |
2,500–3,999 | 1.3 (0.6–2.4) | ||||||||
4,000–4,499 | 1.2 (0.0–6.7) | ||||||||
≥ 4,500 | 1.3 (0.7–2.3) | ||||||||
[22] | 2000 | Cohort | 37 | 2,221 | UK | All ages | Adjusted for age. P for trend = 0.03 among premenopausal women | ||
<3,000 | Referent | ||||||||
3,000–3,499 | 1.05 (0.41–2.71) | ||||||||
3,500–3,999 | 1.76 (0.72–4.33) | ||||||||
≥ 4,000 | 2.02 (0.59–6.90) | ||||||||
Premenopausal ages | |||||||||
<3,000 | Referent | ||||||||
3,000–3,499 | 1.99 (0.40–9.86) | ||||||||
3,500–3,999 | 3.26 (0.69–15.36) | ||||||||
≥ 4,000 | 5.65 (0.95–33.84) | ||||||||
[38] | 2001 | LCohort | 177 | 3,447 | Sweden | ≤ 2,000 | Referent | Crude hazard ratios | |
2,001–2,500 | 1.4 (0.6–3.4) | ||||||||
2,501–3,000 | 1.9 (0.8–4.3) | ||||||||
3,001–3,500 | 1.5 (0.6–3.5) | ||||||||
≥ 3,501 | 1.9 (0.7–5.0) | ||||||||
[39] | 2001 | Cohort | 62 | 1260 | Sweden | ≤ 3,000 | Referent | Singleton only; adjusted for gestational age and cohort membership | |
3,010–3,349 | 1.16 (0.47–2.87) | ||||||||
3,350–3,590 | 1.65 (0.71–3.86) | ||||||||
3,600–3,960 | 1.58 (0.67–3.72) | ||||||||
≥ 4,000 | 1.57 (0.67–3.64) | ||||||||
[23] | 2003 | LCohort | 63 | 5,352 | Sweden | <3,000 | Referent | Crude ORs;P for trend = 0.01 | |
3,000–3,499 | 1.46 (0.60–3.43) | ||||||||
3,500–3,999 | 2.09 (0.90–4.85) | ||||||||
≥ 4,000 | 2.78 (1.10–7.15) | ||||||||
[24] | 2003 | LCohort | 2,334 | 106,504 | Denmark | 1,000 g increase | 9 (0.02–17)% | Adjusted for age and calendar period. Additional adjustment for parity and age at first birth did not indicate confounding | |
[25] | 2003 | LCohort | 39 | 1483 | Sweden | 500–1,999 | 1.14 (0.70–1.85) | Standardized incidence ratio (expected/observed) | |
2,000–2,999 | 0.71 (0.40–1.15) | ||||||||
≥ 3,000 | 2.55 (1.03–5.25) | ||||||||
[26]a | 2004 | LCohort | 2,074 | 91,601 | Denmark | Median of each quintile | Adjusted for age and calendar period. No change in estimates when additionally adjusted for parity and age at first birth | ||
2.5 | Referent | ||||||||
3.0 | 0.98 (0.85–1.13) | ||||||||
3.4 | 1.06 (0.93–1.20) | ||||||||
3.6 | 1.05 (0.87–1.27) | ||||||||
4.0 | 1.17 (1.02–1.33) | ||||||||
[27] | 2004 | Cohort | 59 | 2,176 | UK | <3,000 | Referent | Adjusted for age; P for trend = 0.03 | |
3,000–3,499 | 1.37 (0.34–5.47) | ||||||||
3,500–3,999 | 2.18 (0.58–8.21) | ||||||||
≥ 4,000 | 5.03 (1.13–22.47) | ||||||||
[28] | 2005 | LCohort | 311 | 16,011 | USA | <3,040 | Referent | Adjusted for year of birth | |
3,040–3,310 | 1.4 (1.0–2.1) | ||||||||
3,320–3,550 | 1.0 (0.6–1.5) | ||||||||
3,560–3,830 | 1.3 (0.9–1.9) | ||||||||
≥ 3,840 | 1.5 (1.0–2.2) | ||||||||
[29]a | 2005 | LCohort | 367 | 5,346 | Sweden | <50 years | |||
<3,000 | Referent | ||||||||
3,000–3,499 | 1.81 (0.77–4.26) | ||||||||
3,500–3,999 | 2.66 (1.09–6.46) | ||||||||
≥ 4,000 | 4.00 (1.49–10.72) | ||||||||
≥ 50 years | |||||||||
<3,000 | Referent | ||||||||
3,000–3,499 | 0.86 (0.62–1.19) | ||||||||
3,500–3,999 | 1.06 (1.20–3.34) | ||||||||
≥ 4,000 | 0.91 (0.57–1.46) | ||||||||
[40] | 2006 | Cohort | 97 | 5,847 | USA | <3,000 | 0.98 (0.61–1.60) | Adjusted for age | |
3,000–3,499 | Referent | ||||||||
≥ 3,500 | 1.09 (0.66–1.80) | ||||||||
[30] | 2006 | Cohort | 3,140 | 91,601 | USA | Premenopause | Adjusted for age: P for trend = 0.019 | ||
<2,495 | 0.69 (0.50–0.94) | ||||||||
2,495–3,130 | 0.79 (0.64–0.97) | ||||||||
3,131–3,810 | 0.76 (0.63–0.93) | ||||||||
>3,810 | Referent | ||||||||
Postmenopause: | Adjusted for age: P for trend = 0.99 | ||||||||
<2,495 | 1.04 (0.88–1.23) | ||||||||
2,495–3,130 | 1.00 (0.87–1.14) | ||||||||
3,131–3,855 | 1.05 (0.93–1.20) | ||||||||
>3,855 | Referent | ||||||||
[31] | 2006 | Cohort | 209 | 1,024 | USA | <2,500 | 0.9 (0.5–1.6) | Hazard ratio; adjusted for age at diagnosis, diagnosis year, stage at diagnosis, and birth order, with exception of birth order, which is adjusted for maternal age | |
2,500–3,999 | Referent | ||||||||
≥ 4,000 | 1.8 (1.0–3.1) | ||||||||
(P trend = 0.1) | |||||||||
[41] | 2007 | Cohort | 657 | 38,566 | Sweden | <2,500 | 0.65 (0.43–0.99) | Adjusted for adult body mass index | |
2,500–3,000 | 1.04 (0.86–1.25) | ||||||||
>3,000 | Referent |
Type of study | Ref. | Year | Design | Cases | Controls (or cohort) | Country/place of study | Birth order | OR (95% CI) | Comments |
---|---|---|---|---|---|---|---|---|---|
Case-control studies | [51] | 1967 | LCC-D | 229 | 229 | USA | 1 | - | The authors measured the mean value of birth weight instead of providing ORs (95% CIs). The mean difference between cases and matched controls was not significant (P > 0.2). They provided the frequency of each case and control in the tables and we calculated crude ORs |
2 | |||||||||
3 | |||||||||
4 | |||||||||
5 | |||||||||
6 | |||||||||
≥ 7 | |||||||||
[50]a | 1980 | MCC | 4339 | 12,760 | USA, Japan, Slovenia, Athens, Taipei | 1 | Referent | The risks (point estimates) only by birth order were shown in the figure in the original article. | |
2 | 0.93 | ||||||||
3 | 1.08 | ||||||||
4 | 0.99 | ||||||||
5 | 1.05 | ||||||||
6 | 1.07 | ||||||||
7 | 1.18 | ||||||||
≥ 8 | 1.02 | ||||||||
[42] | 1988 | PCC | 153 | 461 | USA | 1 | Referent | P for trend = 0.16 | |
2 | 0.92 (0.55–1.54) | ||||||||
3 | 0.98 (0.58–1.72) | ||||||||
4 | 0.69 (0.36–1.32) | ||||||||
≥ 5 | 1.03 (0.60–1.79) | ||||||||
[46] | 1991 | MCC | 927 | 2,616 | USA/Wales/Japan | All ages | Adjusted for age, study center, parity, age at first birth, age at menarche, height, body mass index, maternal age at birth, and menopausal status | ||
1 | Referent | ||||||||
2 | 0.91 (0.73–1.02) | ||||||||
3 | 1.11 (0.87–1.27) | ||||||||
≥ 4 | 1.09 (0.81–1.18) | ||||||||
Premenopausal | |||||||||
1 | Referent | ||||||||
≥ 2 | 0.76 (0.60–0.96) | ||||||||
[12] | 1992 | LCC | 458 | 1,197 | Sweden | 1 | Referent | Adjusted for age and birth date | |
≥ 2 | 1.00 (0.76–1.32) | ||||||||
[47] | 1994 | PCC | 2,414 | 9,138 | USA | 1 | Referent | Adjusted for age at first birth and number of children | |
2 | 0.90 (0.78–1.03) | ||||||||
3 | 0.98 (0.84–1.14) | ||||||||
4 | 0.86 (0.73–1.02) | ||||||||
5 | 0.93 (0.78–1.11) | ||||||||
6 | 1.02 (0.84–1.23) | ||||||||
7 | 0.91 (0.73–1.14) | ||||||||
≥ 8 | 0.88 (0.75–1.04) | ||||||||
[14] | 1996 | PCC | 1,129 | 1,393 | USA | 1 | Referent | Adjusted for age, menopausal status, and maternal smoking; P for trend = 0.06 among both groups | |
2 | 1.0 (0.7–1.4) | ||||||||
≥ 3 | 0.8 (0.6–1.1) | ||||||||
[32] | 1997 | NCC | 1,068 | 2,727 | Sweden | 1 | Referent | Adjusted for maternal age, socioeconomic status, parity, and preeclampsia or eclampsia, neonatal jaundice, severe prematurity, and twinship | |
2 | 1.01 (0.83–1.22) | ||||||||
≥ 3 | 1.01 (0.81–1.26) | ||||||||
[15] | 2000 | LCC | 481 | 2,863 | USA | 1 | 1.07 (0.84–1.35) | Crude ORs | |
2–3 | Referent | ||||||||
4–5 | 1.06 (0.81–1.38) | ||||||||
≥ 6 | 1.50 (1.06–2.13) | ||||||||
[35] | 2002 | PCC | 1,555 | 1,539 | USA | 1 | Referent | Adjusted for age and residential regions (states) | |
2 | 1.07 (0.88–1.30) | ||||||||
3 | 1.07 (0.85–1.35) | ||||||||
4 | 1.01 (0.77–1.31) | ||||||||
5 | 0.66 (0.48–0.92) | ||||||||
≥ 6 | 0.81 (0.62–1.08) | ||||||||
[18] | 2003 | LCC | 881 | 3,423 | Denmark | 1 | Referent | Adjusted for mother's marital status, maternal age, and birth order | |
≥ 2 | 1.01 (0.83–1.12) | ||||||||
[36] | 2004 | PCC | 854 | 785 | USA | All subjects | Adjusted for age, race and sampling fractions, body mass index, hosehold income, maternal age | ||
1 | Referent | ||||||||
2–4 | 0.9 (0.7–1.1) | ||||||||
≥ 5 | 1.0 (0.8–1.3) | ||||||||
Born ≥ 1948 | |||||||||
1 | Referent | ||||||||
2–4 | 0.9 (0.6–1.4) | ||||||||
≥ 5 | 0.6 (0.3–1.3) | ||||||||
[48]a | 2005 | MCC | 24 | 34 | Nigeria | ≤ 3 | Referent | Crude ORs | |
≥ 4 | 1.50 (0.25–8.98) | ||||||||
[20] | 2005 | PCC | 1642 | 1,713 | Poland | 1 | Referent | Adjusted for age, education, age at menarche, menopausal status and age at menopause, age at first full-term pregnancy, number of full-term pregnancies, family history of breast cancer among first-degree relatives, mammography screening, and current body mass index | |
2 | 1.07 (0.91–1.24) | ||||||||
3–5 | 0.99 (0.85–1.15) | ||||||||
≥ 6 | 0.81 (0.61–1.06) | ||||||||
P for trend = 0.81 | |||||||||
[37] | 2006 | PCC | 1,166 | 2,105 | USA | 1 | Referent | Adjusted for age (years), education (years), race, body mass index, history of breast benign disease, family history of breast cancer, lactation (months), age at menarche (years), age at first full-term pregnancy (years), age at menopause (years), parity | |
≥ 2 | 1.27 (0.88–1.85) | ||||||||
Cohort studies | [31] | 2006 | Cohort | 209 | 1,024 | USA | 1 | Referent | Hazard ratio for breast cancer mortality: adjusted for age at diagnosis, diagnosis year, stage at diagnosis, and birth order, with exception of birth order, which is adjusted for maternal age |
2 | 0.2 (0.2–0.3) | ||||||||
≥ 3 | 0.2 (0.2–0.3) | ||||||||
P for trend < 0.01 | |||||||||
[49]a | 2001 | Cohort | - | - | Sweden | Continuous scale | 1.05 (1.01–1.10) |
Ref. | Year | Design | Cases | Controls (or cohort) | Country/place of study | Maternal age (years) | OR (95% CI) | Comments | |
---|---|---|---|---|---|---|---|---|---|
Case-control studies | [51] | 1967 | LCC-D | 229 | 229 | USA | ≤ 19 | Mean maternal age among cases was higher than that among controls (P < 0.005). The frequency of each case and control were shown in the tables provided and we calculated crude ORs | |
20–24 | |||||||||
25–29 | |||||||||
30–34 | |||||||||
35–39 | |||||||||
≥ 40 | |||||||||
[61]a | 1974 | PCC | 308 | 308 | USA | Matched analysis; the mean maternal age was 27.3 years among cases and 26.3 years among controls (P < 0.01) | |||
[50]b | 1980 | MCC | 4339 | 12760 | USA, Japan, Slovenia, Athens, Taipei | ≤ 19 | Referent | Authors showed point estimates of ORs without 95% CIs. The frequencies for each case and control were given in the tables provided and we calculated crude ORs | |
20–24 | 1.05 | ||||||||
25–29 | 1.22 | ||||||||
30–34 | 1.19 | ||||||||
35–39 | 1.31 | ||||||||
≥ 40 | 1.18 | ||||||||
[53]a | 1984 | MCC | 1,176 | 1,176 | England | ≤ 20 | Referent | Adjusted for age, social class, family history of breast cancer, age at first-term birth, past history of benign breast disease, age at menarche, menopausal status, cigarette smoking, and oral contraceptive use | |
21–25 | 1.41 (0.92–2.18) | ||||||||
26–30 | 1.19 (0.78–1.81) | ||||||||
31–35 | 1.29 (0.83–1.98) | ||||||||
≥ 36 | 1.19 (0.68–1.67) | ||||||||
[42]a | 1988 | PCC | 153 | 461 | USA | All women | Matched analysis | ||
15–22 | 1.18 (0.71–1.97) | ||||||||
23–26 | Referent | ||||||||
27–30 | 1.22 (0.71–2.10) | ||||||||
31–46 | 1.66 (0.99–2.78) | ||||||||
P for trend = 0.67 | |||||||||
Younger women | |||||||||
15–23 | 1.39 (0.65–2.95) | ||||||||
24–28 | Referent | ||||||||
29–46 | 2.21 (1.02–4.80) | ||||||||
P for trend = 0.08 | |||||||||
[52]a | 1989 | PCC | 801 | 1,573 | USA | Continuous | 1.24 (1.09–1.41) | Crude OR | |
[54] | 1990 | PCC | 2,291 | 3,144 | USA | ≤ 19 | Referent | Adjusted for age and parity, age at first pregnancy, total duration of breast feeding, race, age at menarche, menopausal status, body mass index, family history of breast cancer, and breast biopsy | |
20–24 | 0.95 (0.77–1.16) | ||||||||
25–29 | 1.13 (0.92–1.38) | ||||||||
30–34 | 1.16 (0.93–1.45) | ||||||||
35–39 | 1.46 (1.10–1.93) | ||||||||
≥ 40 | 1.20 (0.79–1.83) | ||||||||
[55] | 1991 | PCC | 1761 | 1,116,553 person-years | USA | ≤ 19 | Referent | Crude ORs | |
20–24 | 1.02 (0.82–1.46) | ||||||||
25–29 | 1.12 (1.04–1.38) | ||||||||
30–34 | 1.16 (0.93–1.44) | ||||||||
35–39 | 1.17 (0.92–1.48) | ||||||||
≥ 40 | 1.08 (0.80–1.46) | ||||||||
[46]a | 1991 | MCC | 927 | 2616 | USA, Wales, Japan | Each 5-yrs | 1.06 (1.01–1.10) | Adjusted for age, study center, parity, age at first birth, age at menarche, height, BMI, maternal age at birth, and menopausal status | |
[12]b | 1992 | LCC | 458 | 1,197 | Sweden | Each 5-year band | 1.01 (0.92–1.12) | Adjusted for age and birth date. The authors estimated breast cancer risk according to each 5-year band of maternal age. The frequency of each case and control were given in the tables provided and we calculated crude ORs | |
[47] | 1994 | PCC | 2,412 | 9,138 | USA | ≤ 19 | Referent | Adjusted for age at first birth and number of children | |
20–24 | 1.05 (0.85–1.30) | ||||||||
25–29 | 1.10 (0.89–1.37) | ||||||||
30–34 | 1.10 (0.88–1.37) | ||||||||
35–39 | 1.09 (0.87–1.37) | ||||||||
≥ 40 | 0.99 (0.76–1.28) | ||||||||
[14] | 1996 | PCC | 1,934 | 2,161 | USA | ≤ 24 | Referent | Adjusted for age, menopausal status, and maternal smoking | |
25–29 | 1.0 (0.8–1.2) | ||||||||
30–34 | 0.9 (0.6–1.1) | ||||||||
≥ 35 | 1.0 (0.7–1.5) | ||||||||
[57] | 1997 | PCC | 1,253 | 1,121 | USA | ≤ 19 | Referent | Adjusted for age, menopausal status, age at menarche, parity, age at first birth, body mass index, past history of benign breast disease, and recent alcohol intake | |
20–24 | 0.84 (0.62–1.14) | ||||||||
25–29 | 1.02 (0.76–1.37) | ||||||||
30–34 | 0.93 (0.68–1.28) | ||||||||
35–39 | 1.16 (0.82–1.65) | ||||||||
≥ 40 | 0.92 (0.62–1.37) | ||||||||
[58] | 1997 | PCC | 2,106 | 1,926 | USA | ≤ 19 | Referent | Adjusted for age, study site, family history of breast cancer, breast biopsy, a combination variable including number of full-term births and age at first full-term pregnancy, age at menarche, menopausal status, body mass index, average lifetime alcohol consumption, and the number of mammograms | |
20–24 | 0.96 (0.7–1.2) | ||||||||
25–29 | 0.96 (0.7–1.2) | ||||||||
30–34 | 0.91 (0.7–1.2) | ||||||||
≥ 35 | 0.93 (0.7–1.3) | ||||||||
[32]a | 1997 | NCC | 1,067 | 2,725 | Sweden | Each 5-year band | 1.06 (0.99–1.14) | Adjusted for maternal age, socioeconomic status, parity, and pre-eclampsia or eclampsia, neonatal jaundice, severe prematurity, and twinship | |
[15] | 2000 | LCC | 481 | 2863 | USA | ≤ 19 | 1.19 (0.83–1.72) | Crude ORs | |
20–24 | Referent | ||||||||
25–29 | 1.26 (0.97–1.64) | ||||||||
30–34 | 1.38 (1.04–1.84) | ||||||||
≥ 35 | 1.70 (1.23–2.35) | ||||||||
[35] | 2002 | PCC | 1,555 | 1,539 | USA | ≤ 19 | 1.02 (0.75–1.39) | Adjusted for age and state | |
20–24 | 0.98 (0.81–1.18) | ||||||||
25–29 | Referent | ||||||||
30–34 | 1.15 (0.93–1.42) | ||||||||
35–39 | 1.22 (0.94–1.58) | ||||||||
≥ 40 | 1.27 (0.90–1.69) | ||||||||
[18] | 2003 | LCC | 881 | 3,423 | Denmark | ≤ 24 | Referent | Adjusted for mother's marital status, maternal age, and birth order | |
25–29 | 1.08 (0.88–1.32) | ||||||||
≥ 30 | 1.11 (0.90–1.36) | ||||||||
[36]a | 2004 | PCC | 854 | 785 | USA | ≤ 18 | 1.8 (0.9–3.4) | ||
19–22 | Referent | Adjusted for age, race and sampling fractions; tertiles are race specific with cutpoints derived from controls | |||||||
23–27 | 3.0 (1.8–5.0) | ||||||||
≥ 28 | 2.5 (1.6–4.0) | ||||||||
[56] | 2005 | MCC | 1,060 | 1,060 | Korea | ≤ 24 | Referent | Adjusted for age, family history of breast cancer in first-or second-degree relatives, menopausal status, and lifetime estrogen exposure duration | |
25–29 | 1.2 (0.93–1.47) | ||||||||
30–34 | 1.4 (1.12–1.83) | ||||||||
≥ 35 | 1.1 (0.83–1.37) | ||||||||
[20] | 2006 | PCC | 1,642 | 1,713 | Poland | ≤ 19 | Referent | Adjusted for: age, education, age at menarche, menopausal status and age at menopause, age at first full-term pregnancy, number of full-term pregnancies, family history of breast cancer among first-degree relatives, mammography screening, and current body mass index | |
20–24 | 1.02 (0.75–1.39) | ||||||||
25–29 | 1.07 (0.79–1.46) | ||||||||
35–39 | 1.16 (0.84–1.60) | ||||||||
≥ 35 | 0.91 (0.66–1.27) | ||||||||
P for trend = 0.76 | |||||||||
[37]a | 2006 | PCC | 1,166 | 2,105 | USA | ≤ 24 | Referent | Adjusted for: age, education, race, body mass index, history of breast benign disease, family history of breast cancer, lactation, age at menarche, age at first full-term pregnancy, age at menopause, and parity | |
25–35 | 0.87 (0.67–1.13) | ||||||||
>35 | 0.87 (0.59–1.27) | ||||||||
Cohort studies | [59] | 1995 | Cohort | 149 | 75,237 | USA | ≤ 24 | Referent | Adjusted for age, education, menopausal status, parity, body mass index, height, smoking, and alcohol drinking |
25–29 | 1.3 (0.8–2.0) | ||||||||
30–34 | 1.4 (0.9–2.1) | ||||||||
≥ 35 | 1.2 (0.7–2.0) | ||||||||
[60] | 1995 | Cohort | 1,967 | 384,769 | Sweden | ≤ 19 | Referent | Breast cancer mortality; adjusted for age | |
20–24 | 0.99 (0.82–1.21) | ||||||||
25–29 | 1.00 (0.82–1.22) | ||||||||
30–34 | 0.97 (0.79–1.18) | ||||||||
35–39 | 1.04 (0.84–1.29) | ||||||||
40–44 | 0.93 (0.71–1.21) | ||||||||
≥ 45 | 1.39 (0.91–2.13) | ||||||||
[49]a | 2001 | Cohort | Sweden | Continuous scale | 1.07 (0.91–1.27) | Adjusted for spouse age, year of diagnosis, and birth order | |||
[38]a | 2001 | Cohort | 177 | 3,447 | Filand | Continuous scale | - | No association | |
[31] | 2006 | Cohort | 249 | 1,024 | USA | ≤ 24 | Referent | Hazard ratio; adjusted for age at diagnosis, diagnosis year, stage at diagnosis, and birth order, with exception of birth order, which is adjusted for maternal age | |
25–29 | 1.2 (0.9–1.7) | ||||||||
30–34 | 1.4 (0.9–1.9) | ||||||||
≥ 35 | 1.7 (1.1–2.8) | ||||||||
P for trend = 0.03 |
Type of study | Author | Year | Design | Cases | Controls (or cohort) | Country/place of study | Gestational age (weeks) | OR (95% CI) | Comments |
---|---|---|---|---|---|---|---|---|---|
Case-control studies | [42]a | 1988 | PCC | 153 | 461 | USA | 25–32 | 1.16 (0.50–1.54) | Matched analysis |
33–40 | Referent | ||||||||
[13]b | 1996 | NCC | 571 | 1,525 | USA | Categorical | Adjusted for age | ||
40 | Referent | ||||||||
38–39 | 0.76 (0.44–1.32) | ||||||||
36–37 | 0.96 (0.59–1.56) | ||||||||
Binomial | |||||||||
≥ 37 | Referent | ||||||||
≤ 36 | 0.82 (0.37–1.82) | ||||||||
[14] | 1996 | PCC | 1123 | 1371 | USA | Nonpreterm | Referent | Adjusted for age, menopausal status, and maternal smoking | |
Preterm | 1.1 (0.5–2.1) | ||||||||
[32]a | 1997 | NCC | 1,010 | 2,625 | Sweden | ≥ 33 | Referent | Adjusted for maternal age, matermal socioeconomic status, maternal parity, maternal pre-eclampsia or eclampsia, neonatal jaundice, severe prematurity, twin, and birth weight | |
≤ 32 | 3.96 (1.46–10.81) | ||||||||
[33]b | 1998 | PCC | 502 | 433 | USA | ≥ 43 | 1.5 (0.8–2.6) | Crude ORs | |
37–42 | Referent | ||||||||
≤ 36 | 0.9 (0.5–1.8) | ||||||||
[15]a,b | 2000 | LCC | 480 | 2,854 | USA | ≥ 37 | Referent | Crude ORs | |
33–36 | 1.34 (0.85–2.13) | ||||||||
≤ 32 | 0.55 (0.19–1.57) | ||||||||
[34]a,b | 2001 | LCC | 87 | 87 | Sweden | ≥ 40 | 8.4 (1.3–54.4) | Matched analysis by conditional logistic regression | |
37–40 | 3.4 (0.7–17.0) | ||||||||
33–36 | 3.5 (0.7–17.5) | ||||||||
≤ 32 | Referent | ||||||||
[25]a | 2003 | LCohort | 127 | (1,483) | Sweden | ≥ 33 | 1.08 (0.64–1.70) | Standardized incidence ratio (expected/observed) | |
≤ 32 | 0.92 (0.57–1.41) | ||||||||
[45]a,b | 2004 | LCC | 2,471 | 9,801 | USA | ≥ 37 | Referent | Adjusted for age and maternal age at first birth | |
32–36 | 0.91 (0.72–1.13) | ||||||||
≤ 31 | 1.43 (0.90–2.28) | ||||||||
[20]b | 2005 | PCC | 1,424 | 1,457 | Poland | ≥ 37 | Referent | Adjusted for age, education, age at menarche, menopausal status and age at menopause, age at first full-term pregnancy, number of full-term pregnancies, family history of breast cancer among first-degree relatives, mammography screening, and current body mass index | |
≤ 36 | 1.01 (0.75–1.32) | ||||||||
Cohort studies | [62]c | 2000 | LCohort | 12 | 273 | Sweden | 35 | 0.2 (0.01–1.3) | Standardized incidence ratio |
33–34 | 0.7 (0.1–2.0) | ||||||||
31–32 | 2.3 (0.7–5.3) | ||||||||
<31 | 6.7 (1.4–19.5) | ||||||||
[16]c | 2001 | LTCCS | 2,265 | 9,060 | Sweden | 33–36 | Referent | Crude ORs | |
37–38 | 1.8 (0.83–4.0) | ||||||||
40–44 | 2.0 (0.88–4.6) | ||||||||
[29]c | 2005 | LCohort | 367 | 5,346 | Sweden | 1 week increase | <50 years | ||
0.94 (0.83–1.07) | |||||||||
[40]c | 2006 | Cohort | 97 | 5,847 | USA | <39 | 0.77 (0.42–1.4) | Adjusted for age | |
39 | 1.38 (0.78–2.4) | ||||||||
40 | Referent | ||||||||
41+ | 1.33 (0.67–2.6) | ||||||||
[31]b | 2006 | Cohort | 249 | 1024 | USA | ≥ 43 | 0.7 (0.2–2.7) | Adjusted for: age at diagnosis, diagnosis year, stage at diagnosis, and birth order, with exception of birth order, which is adjusted for maternal age | |
37–42 | Referent | ||||||||
<37 | 1.4 (0.7–2.9) | ||||||||
P for trend = 0.3 |
Type of study | Ref. | Year | Design | Cases | Controls (or cohort) | Country/place of study | Category | OR (95% CI) | Comments |
---|---|---|---|---|---|---|---|---|---|
Case-control studies | [63]a | 1992 | MCC | 870 | 2,741 | UK, USA | Singleton | Referent | Adjusted for age, study center, parity, age at first birth, age at menarche, height, body mass index, maternal age at birth, birth order, and menopausal status |
Twinship | 1.40 (0.77–2.55) | ||||||||
Singleton | Referent | ||||||||
Monozygote twin | 1.30 (0.58–2.92) | ||||||||
Dizygote twin | 1.54 (0.64–3.71) | ||||||||
[14] | 1996 | PCC | 1,134 | 1,380 | USA | Age 21–45 | Adjusted for age, menopausal status, and maternal smoking | ||
Singleton | Referent | ||||||||
Twinship | 0.6 (0.3–1.3) | ||||||||
Age 50–64 | |||||||||
Singleton | Referent | ||||||||
Twinship | 0.9 (0.4–2.2) | ||||||||
[58]a | 1997 | PCC | 2,150 | 1,961 | USA | Singleton | Referent | Adjusted for age, study site, family history of breast cancer, breast biopsy, a combination variable including number of full-term births and age at first full-term pregnancy, age at menarche, menopausal status, body mass index, average lifetime alcohol consumption, and the number of mammograms | |
Twinship | 1.6 (1.0–2.7) | ||||||||
Singleton | Referent | ||||||||
Monozygote twin | 1.39 (0.7–2.6) | ||||||||
Dizygote twin | 2.06 (1.0–4.5) | ||||||||
[32] | 1997 | NCC | 1,068 | 2,727 | Sweden | Singleton | Referent | Adjusted for maternal age, matermal socioeconomic status, maternal parity, maternal pre-eclampsia or eclampsia, neonatal jaundice, severe prematurity, twin, and birth weight | |
Twinship | 1.3 (0.8–2.1) | ||||||||
Singleton | Referent | ||||||||
Monozygote twin | 0.7 (0.2–2.2) | ||||||||
Dizygote twin | 1.5 (0.8–2.7) | ||||||||
[15] | 2000 | LCC | 481 | 2,863 | USA | Singleton | Referent | Crude ORs | |
Twinship | 1.04 (0.51–2.11) | ||||||||
[43] | 2001 | LCC | 319 | 768 | USA | Singleton | Referent | Crude ORs | |
Twinship | 1.6 (0.2–10.1) | ||||||||
[45] | 2004 | LCC | 2,522 | 10,052 | USA | Singleton | Referent | Adjusted for age and maternal age at first birth | |
Twinship | 1.77 (1.05–2.97) | ||||||||
[20] | 2005 | PCC | 2,338 | 2,476 | Poland | Singleton | Referent | Adjusted for age, education, age at menarche, menopausal status and age at menopause, age at first full-term pregnancy, number of full-term pregnancy, family history of breast cancer among first-degree relatives, mammography screening, and current body mass index | |
Twinship | 0.76 (0.49–1.16) | ||||||||
Singleton | Referent | ||||||||
Monozygote twin | 0.90 (0.53–1.52) | ||||||||
Dizygote twin | 0.58 (0.23–1.47) | ||||||||
Cohort studies | [64] | 1980 | LTCohort | 270 | (16,922) | Denmark | Twinship | 1.1 (1.0–1.2) | Observed/expected ratio (95% CI) |
[65] | 1995 | LTCohort | 740 | (25,541) | Sweden | Twinship | 1.1 (1.0–1.1) | Observed/expected ratio (95% CI) | |
Monozygote twin | 1.0 (0.9–1.2) | ||||||||
Dizygote twin | 1.1 (1.0–1.2) | ||||||||
[67] | 1999 | LTCohort | 245 | (13,176) | Finland | Twinship | 0.91 (0.81–1.00) | Observed/expected ratio (95% CI) | |
Monozygote twin | 0.76 (0.59–0.97) | ||||||||
Dizygote twin | 0.98 (0.84–1.10) | ||||||||
[66] | 2000 | Cohort | 1,230 | (29,197) | USA | Singleton | Referent | Adjusted for age, education, family history of breast cancer, age at menarche, age at first birth, height, current body mass index, body mass index at age 18, waist:hip ratio, alcohol drinking, and hormone replacement therapy | |
Twinship | 1.72 (1.22–2.42) | ||||||||
Singleton | Referent | ||||||||
Monozygote twin | 1.04 (0.43–2.5) | ||||||||
Dizygote twin | 1.77 (1.16–2.7) | ||||||||
[31] | 2006 | Cohort | 249 | 1,024 | USA | Singleton | Referent | Adjusted for age at diagnosis, diagnosis year, stage at diagnosis, and birth order, with exception of birth order, which is adjusted for maternal age | |
Twinship | 2.5 (1.0–6.2) |
Type of study | Ref. | Year | Design | Cases | Controls (or cohort) | Country/place of study | Smoking status | OR (95% CI) | Comments |
---|---|---|---|---|---|---|---|---|---|
Case-control studies | [69] | 1996 | PCC | 53 | 470 | USA | Maternal smoking | Crude ORs | |
No | Referent | ||||||||
Yes | 0.9 (0.4–2.1) | ||||||||
Paternal smoking | |||||||||
No | Referent | ||||||||
Yes | 1.3 (0.9–1.7) | ||||||||
[14] | 1996 | PCC | 1,086 | 1,321 | USA | Maternal smoking | Adjusted for age, menopausal status, and maternal smoking; OR (95% CI) for maternal smoking among early-onset breast cancer patients (≤ 30 years old) was 1.9 (1.0–3.4) | ||
Age 21–45 years | |||||||||
No | Referent | ||||||||
Yes | 1.1 (0.9–1.3) | ||||||||
Age 50–64 years | |||||||||
No | Referent | ||||||||
Yes | 1.3 (0.9–2.1) | ||||||||
[58] | 1997 | PCC | 522 | 484 | USA | Maternal smoking | Adjusted for age, study site, family history of breast cancer, breast biopsy, a combination variable including number of full-term births and age at first full-term pregnancy, age at menarche, menopausal status, body mass index, average lifetime alcohol consumption, and the number of mammograms | ||
No | Referent | ||||||||
Yes | 1.1 (0.8–1.4) | ||||||||
[33] | 1998 | PCC | 507 | 433 | USA | Maternal smoking | Crude ORs | ||
No | Referent | ||||||||
Yes | 1.1 (0.9–1.5) | ||||||||
[43] | 2001 | LCC | 319 | 768 | USA | Maternal smoking | Adjusted for attained age | ||
No | Referent | ||||||||
Yes | 2.7 (1.1–6.3) | ||||||||
[35]a | 2002 | PCC | 1,535 | 1,534 | USA | Smoking | Adjusted for age and residential regions (states) | ||
No | Referent | ||||||||
Paternal smoking | 1.00 (0.88–1.13) | ||||||||
Maternal/parental smoking | 1.10 (0.84–1.42) | ||||||||
[20] | 2005 | PCC | 2380 | 2,497 | Poland | Maternal smoking | Unadjusted; recalculated | ||
No | Referent | ||||||||
Yes (any exposure) | 1.19 (0.97–1.47) | ||||||||
Paternal smoking | |||||||||
No | Referent | ||||||||
Yes (any exposure) | 0.90 (0.77–1.05) | ||||||||
Cohort studies | [31] | 2006 | Cohort | 249 | 1,024 | USA | Maternal smoking | Referent | Adjusted for age at diagnosis, diagnosis year, stage at diagnosis, and birth order, with exception of birth order, which is adjusted for maternal age Crude relative rates |
No | 0.8 (0.5–1.1) | ||||||||
Yes (any exposure) | |||||||||
[68] | 2005 | Cohort | 42 | (3,989) | USA | Maternal smoking | |||
No | Referent | ||||||||
Yes (any exposure) | 0.49 (0.29–1.03) | ||||||||
≤ 15 cigarettes a day | 0.33 (0.12–0.94) | ||||||||
>15 | 0.68 (0.26–1.73) |