Table 1.
Japanese studies dealing with factors that influence the duration of breastfeeding
| Factors | Authors (Year) | Study design | Sample size (n) | Definition of breastfeeding | Exclusive Breastfeeding rate (%) | Crude OR (95% CI) (subgroup) | Adjusted OR (95% CI) (subgroup) | Study details |
|---|---|---|---|---|---|---|---|---|
|
Maternal age |
Kaneko et al. (2006) [20] |
Cross-sectional |
45,569 |
1. Breastfed |
22.4 at 6m |
1.2 (1.14,1.26) (30-39 years old) |
0.89 (0.84,0.94) (30-39 years old) |
Mothers who are between 20-29 years old = 1 (reference) |
| 2. Only colostrum | ||||||||
| 3. Not breastfeed | ||||||||
| Yokoyama et al. (2006) [21] |
Cross-sectional |
15262 |
1. Breastfeeding only |
N/A |
N/A |
N/A |
|
|
| 2. Mixed-feeding (mainly breast with some bottle or mainly bottle with some breast) | ||||||||
| 3. Bottle feeding with formula milk only | ||||||||
| Otsuka et al. (2008) [22] |
Cross-sectional |
262 |
1. Exclusive Breastfeeding (i.e. breastmilk only) |
40 at 4wks |
5.37 (1.18,24.40) |
N/A |
|
|
| 2. Partial breastfeeding (i.e. breastmilk and formula) | ||||||||
| 3. Bottle-feeding (i.e. no breastmilk at all) | ||||||||
| Sasaki et al (2009) [23] |
Longitudinal |
908 |
1. Only breastfeeding |
27.6 at 3-4m |
N/A |
N/A |
Not statistically significant (p = 0.93) |
|
| 2. Breastmilk and infant formula | ||||||||
| 3. Only infant formula | ||||||||
|
Marital status |
Otsuka et al. (2008) [22] |
Cross-sectional |
262 |
1. Exclusive Breastfeeding (i.e. breastmilk only) |
40 at 4wks |
N/A |
N/A |
Not statistically significant (p = 0.88) |
| 2. Partial breastfeeding (i.e. breastmilk and formula) | ||||||||
| 3. Bottle-feeding (i.e. no breastmilk at all) | ||||||||
|
Socioeconomic status |
Kaneko et al. (2006) [20] |
Cross-sectional |
45,569 |
1. Breastfed |
19 at 6m (< 3.9 million yen) 22 at 6m (> 8.0 million yen) |
0.85 (0.80,0.90) (< 3.9 million yen) 1.03 (0.97,1.08) (> 8.0 million yen) |
0.93 (0.88,0.99) (< 3.9 million yen) 1.03 (0.97,1.09) (> 8.0 million yen) |
4.0-7.9 million yen of annual income = 1 (reference) |
| 2. Only colostrum | ||||||||
| 3. Not breastfeed | ||||||||
| Otsuka et al. (2008) [22] |
Cross-sectional |
262 |
1. Exclusive Breastfeeding (i.e. breastmilk only) |
40 at 4wks |
1.0 (0.26,3.55) (>2,000,000 yen) |
N/A |
Not statistically significant (p = 0.96) |
|
| 2. Partial breastfeedin (i.e. breastmilk and formula) | ||||||||
| 3. Bottle-feeding (i.e. no breastmilk at all) | ||||||||
|
Educational status |
Otsuka et al. (2008) [22] |
Cross-sectional |
262 |
1. Exclusive Breastfeeding (i.e. breastmilk only) |
40 at 4wks |
1.3 (0.66,2.49) (High school or less) |
N/A |
Not statistically significant (p = 0.47) |
| 2. Partial breastfeeding (i.e. breastmilk and formula) | ||||||||
| 3. Bottle-feeding (i.e. no breastmilk at all) | ||||||||
|
Maternal employment status |
Kaneko et al. (2006) [20] |
Cross-sectional |
45,569 |
1. Breastfed |
25.0 at 6m |
1.17 (1.09,1.26) (Full time and child care leave for 6m or more) |
1.14 (1.05,1.23) (Full time and child care leave for 6m or more) |
Non-workers = 1 (reference) |
| |
2. Only colostrum |
|||||||
| 3. Not breastfeed | ||||||||
| Sasaki et al. (2009) [23] |
Longitudinal |
908 |
1. Only breastfeeding |
27.6 at 3-4m |
N/A |
N/A |
Not statistically significant (p = 0.12) |
|
| 2. Breastmilk and infant formula | ||||||||
| 3. Only infant formula | ||||||||
|
Multiple births |
Kaneko et al. (2006) [20] |
Cross-sectional |
46,569 |
1. Breastfed |
1.3 at 6m |
0.05 (0.03,0.09) |
0.07(0.04,0.12) |
Single birth = 1 (reference) |
| 2. Only colostrum | ||||||||
| 3. Not breastfeed | ||||||||
| Yokoyama et al. (2006) [21] |
Cross-sectional |
15,262 |
1. Breastfeeding only |
N/A |
N/A |
N/A |
Multiple births was associated with breastfeeding cessation (adjusted OR = 0.07, 95% CI = 0.04,0.12) |
|
| 2. Mixed-feeding (mainly breast with some bottle or mainly bottle with some breast) | ||||||||
| 3. Bottle feeding with formula milk only | ||||||||
| Ooki (2008) [24] |
Cross-sectional |
4,023 |
1 Full breastfeeding |
6.6 at 6m (Full breastfeeding) |
N/A |
N/A |
Sample were mother who had twin. Any Breastfeeding and formula feeding at 6m were 36.1 and 54.1%, respectively |
|
| 2. Partial breastfeeding (mixed feeding) | ||||||||
| 3. Formula feeding | ||||||||
|
Maternal smoking status |
Kaneko et al. (2006) [20] |
Cross-sectional |
46,324 |
1. Breastfed |
11.5 at 6m |
0.40 (0.31,0.95) |
0.44 (0.34,0.57) |
Nil smoking of the mothers and fathers = 1 (reference) |
| 2. Only colostrum | ||||||||
| 3. Not breastfeed | ||||||||
| Sasaki et al. (2009) [23] |
Longitudinal |
908 |
1. Only breastfeeding |
27.6 at 3-4m |
N/A |
N/A |
Not statistically significant (p = 0.25) |
|
| 2. Breastmilk and infant formula | ||||||||
| 3. Only infant formula | ||||||||
|
Delivery methods |
Nakao et al. (2008) [25] |
Cross-sectional |
318 |
1. Fully breastfeeding (breastmilk was given and infant formula was not given, regardless of whether other liquids and/or solid food were given) |
N/A |
N/A |
1.02 (0.41,2.59) |
Not statistically significant (p = 0.96) |
| 2. Any Breastfeeding (breastmilk and infant formula were given regardless of whether other liquids and/or solid food were given) | ||||||||
| 3. Infant formula feeding (formula was given and breast milk was not given regardless of whether other liquids and/or solid food were given) | ||||||||
| Sasaki et al. (2009) [23] |
Longitudinal |
908 |
1. Only breastfeeding |
N/A |
N/A |
N/A |
Not statistically significant (p = 0.14 for chi square test) |
|
| 2. Breastmilk and infant formula | ||||||||
| 3. Only infant formula | ||||||||
|
Parity |
Kaneko et al. (2006) [20] |
Cross-sectional |
45,569 |
1. Breastfed |
24.5 at 6m (Second times) 26.1at 6m (Third times or more) |
1.57 (1.49,1.65) (Second times) 1.71 (1.60-1.81) (Third times or more) |
1.72 (1.63,1.81) (Second times) 2.06 (1.91-2.22) (Third times or more) |
Primipara = 1 (reference) |
| 3. Not breastfeed | ||||||||
| 2. Only colostrum | ||||||||
| Otsuka et al. (2008) [22] |
Cross-sectional |
262 |
1. Exclusive Breastfeeding (i.e. breastmilk only) |
40 at 4wks |
N/A |
N/A |
Not statistically significant (p = 0.90) |
|
| 2. Partial breastfeeding (i.e. breastmilk and formula) | ||||||||
| 3. Bottle-feeding (i.e.no breastmilk at all) | ||||||||
| Sasaki et al. (2009) [23] |
Longitudinal |
908 |
1. Only breastfeeding |
N/A |
N/A |
N/A |
Not statistically significant (p = 0.55) |
|
| 2. Breastmilk and infant formula | ||||||||
| 3. Only infant formula | ||||||||
|
Current intake of alcohols |
Sasaki et al. (2009) [23] |
Longitudinal |
908 |
1. Only breastfeeding |
N/A |
N/A |
1.37 (1.02,1.86) |
Not intake of alcohols = 1 (reference) (p = 0.04) |
| 2. Breastmilk and infant formula | ||||||||
| 3. Only infant formula | ||||||||
|
Early initiation of breastfeeding |
Nakao et al. (2008) [25] |
Cross-sectional |
318 |
1. Fully breastfeeding (breastmilk was given and infant formula was not given, regardless of whether other liquids and/or solid food were given) |
N/A |
N/A |
2.45 (1.21,4.95) |
Initiating breastfeeding within 120 minutes after birth was positively associated with duration of breastfeeding at 4 months (p = 0.01) |
| 2. Any Breastfeeding (breastmilk and infant formula were given regardless of whether other liquids and/or solid food were given) | ||||||||
| 3. Infant formula feeding (formula was given and breast milk was not given regardless of whether other liquids and/or solid food were given) | ||||||||
|
Intention to breastfeed |
Nakamura et al. (2002) [26] |
Cross-sectional |
105 |
1. Breastfeeding |
73.9 at 3m |
N/A |
N/A |
|
| 2. Breast & Bottle feeding | ||||||||
| 3. Artificial milk | ||||||||
| Otsuka et al. (2008) [22] |
Cross-sectional |
262 |
1. Exclusive Breastfeeding (i.e. breastmilk only) |
40 at 4wks |
N/A |
N/A |
Intention to Exclusive Breastfeeding = 1 (reference) |
|
| 2. Partial breastfeeding (i.e. breastmilk and formula) | ||||||||
| |
|
3. Bottle-feeding (i.e. no breastmilk at all) |
||||||
|
Maternal attachment |
Sasano et al. (2005) [27] |
Cross-sectional |
182 |
1. Breastfeeding |
53.4 at 3m |
N/A |
N/A |
|
| 2. Mix and infant formula feeding | ||||||||
|
Breastmilk insufficiency |
Yoshitome et al. (2003) [28] |
Cross-sectional |
246 |
1 Breastfeeding only |
38.5 at 3-4m |
N/A |
N/A |
|
| 2. Mix feeding | ||||||||
| 3. Infant formula only | ||||||||
|
Low birth weight |
Kaneko et al. (2006) [20] |
Cross-sectional |
46,557 |
1. Breastfed |
11.4 at 6m |
0.46 (0.42,0.51) |
0.67 (0.60,0.76) |
≥ 2500g =1 (reference) |
| 2. Only colostrum | ||||||||
| 3. Not breastfeed | ||||||||
|
Maternal confidence |
Awano et al. (2010) [29] |
quasi-experimental |
117 |
1 Fully breastfeeding (no formula was given) |
72.2 at 4 wks (Full breastfeeding) |
N/A |
N/A |
Breastfeeding self-care program is effect to improve maternal confidence |
| Otsuka et al. (2008) [22] |
Cross-sectional |
262 |
1. Exclusive Breastfeeding (i.e. breastmilk only) |
40 at 4wks |
N/A |
N/A |
Maternal confidence level is related to their perception of insufficient breast milk flow. |
|
| 2. Partial breastfeeding (i.e. breastmilk and formula) | ||||||||
| 3. Bottle-feeding (i.e.no breastmilk at all) | ||||||||
|
Sucking difficulty |
Yokoyama et al. (2006) [21] |
Cross-sectional |
15,262 |
1. Breastfeeding only |
N/A |
N/A |
N/A |
Infants with poor sucking ability are 1.56 times more like to be given infant formula (95% CI = 1.12,2.18) |
| 2. Mixed-feeding (mainly breast with some bottle or mainly bottle with some breast) | ||||||||
| 3. Bottle feeding with formula milk only | ||||||||
|
Support from health professionals |
Sasaki et al. (2009) [23] |
Longitudinal |
908 |
1. Only breastfeeding |
N/A |
N/A |
0.83 (0.61,1.12) (Midwives) |
Without support from midwives = 1 (reference) (p = 0.83) |
| 2. Breastmilk and infant formula | ||||||||
| 3. Only infant formula | ||||||||
| Kaneko et al. (2006) [20] |
Cross-sectional |
45,569 |
1. Breastfed |
29.7 at 6m |
1.63 (1.50,1.78) |
1.76 (1.60,1.94) |
Advice on child care from birth attendant/nurse |
|
| 2. Only colostrum | ||||||||
| 3. Not breastfeed | ||||||||
|
Support from husbands/partners |
Kaneko et al. (2006) [20] |
Cross-sectional |
45,569 |
1. Breastfed |
21.8 at 6m |
1.28 (1.21,1.37) |
1.07 (1.00,1.14) |
Support = advice on child care from husbands. No advice =1 (reference) |
| 2. Only colostrum | ||||||||
| 3. Not breastfeed | ||||||||
| Ninomiya et al. (1997) [30] |
Cross-sectional |
264 |
1. Breastfeeding but exclusion of mix breastfeeding |
37.5 at 3m |
N/A |
N/A |
Father’s attendance to an antenatal class is correlated to full breastfeeding duration (p < 0.01). |
|
| Ninomiya et al. (1995) [31] |
Cross-sectional |
719 |
1. Breastfeeding but exclusion of mix breastfeeding |
N/A |
N/A |
N/A |
Father’s involvements in childcare are associated with full breastfeeding duration for three months postpartum (p < 0.05). |
|
|
Family smoking environment |
Kaneko et al. (2006) [20] |
Cross-sectional |
45,569 |
1. Breastfed |
22.6 |
0.90 (0.86,0.95) |
0.92 (0.88,0.97) |
Non-smoking fathers and mothers = 1 (reference) |
| 2. Only colostrum | ||||||||
| 3. Not breastfeed | ||||||||
|
Breastfeeding during night |
Sasaki et al. (2009) [23] |
Longitudinal |
908 |
1. Only breastfeeding |
N/A |
N/A |
2.62(1.85,3.73) |
Not breastfeeding during night =1 (reference) (p < 0.01) |
| |
|
|
|
2. Breastmilk and infant formula |
|
|
|
|
| 3. Only infant formula |
Note: N/A = Not Applicable, wks = weeks postpartum, m = months postpartum.