Table 4 Included studies on maternal obesity and duration of breastfeeding

Amine et al 1989 [51] Kuwait, Year of study not given

Multistage, stratified sample, mothers of children < 3 years old n = 2833

Height and weight recorded at interview Results expressed as % of reference standard weight for height (Nutrition Institute in Cairo, Egypt)

Mean duration of breastfeeding (month):

Weight as % reference median:

80% 4.48 (sd 2.3)

85–119% 5.46 (sd 3.1)

120% 6.36 (sd 3.6)

Baker 2004 [50] Denmark, 1996 onwards

National Birth Cohort Excluded infants <2500 g, <37w gestation, illnesses or conditions expected to negatively affect growth, mother <18y, never breastfeed, mother diabetic n = 3768

BMI calculated from pre-pregnant weight and height

WHO definition of obesity

Full breastfeeding

Underweight 15.5 wk

Normal weight 16.3 wk

Overweight 15.6 wk

Obese 14.9 wk

Any breastfeeding

Underweight 29.5 wk

Normal weight 31.3 wk

Overweight 29.2 wk

Obese 27.3 wk

NS

Chapman & Perez-Escamilla 2000 [46] USA, 1997–1998

Connecticut Healthy mothers with a healthy, single, term infant, Caesarean section n = 57

Definition of obesity: at least 2 of 3:

1. BMI at 72 h > 30,

2. subscapular skin fold thickness at 72 h > 33.7 mm (> 85%ile)

3. heavy/obese build on day 1

Multivariate analysis, likelihood of not bf:

Non-obese: OR 2.28 (95%CI: 1.02, 5.11) compared with obese women

(adjusted for maternal intention, milk transfer and other variables, Table 3, model 1)

{Sample too small for multivariate analysis}

Donath & Amir 2000 [13] Australia, 1992–1995

National Health Survey, 1995 Children up to 4 years old Multivariate analysis: n = 1991

BMI calculated at time of interview

WHO definition of obesity

Mean duration % (95% CI)

Normal 28.7 (27.7, 29.8)

Overweight 26.1 (24.3, 28.0)

Obese 22.7 (20.1, 25.2)

Multivariate analysis

Normal 1

Overweight 1.15 (1.01, 1.31)

Obese 1.36 (1.15, 1.61)

p < 0.05

(adjusted for maternal education, marital status, low income, home ownership)

Forster et al 2006 [48] Australia, 1999–2001

Cohort of public patients, Melbourne n = 764

BMI calculated from self-reported height and weight

WHO definition of obesity

Any breastfeeding at 6 months:

Underweight 60.0%

Normal 57.0%

Overweight 51.9%

Obese 37.2%

Multivariate analysis: OR (95% CI)

Underweight 1.15 (0.70, 1.88)

Normal 1

Overweight 0.70 (0.43, 1.12)

Obese 0.49 (0.28, 0.85)

(adjusted for intention, breastfed as a baby, maternal age, smoking, region of birth, attended childbirth education, had formula in hospital, maternal anxiety/depression)

Grjibovski et al 2005 [43] Russia, 1999

Community-based cohort, all pregnant women at antenatal clinics, Severodvinsk n = 1078

Pre-pregnancy weight

Defined as under-, normal and over-weight based on "doctor's diagnosis" [82]

Median duration (months, 25th, 75 ^th percentile):

Underweight 5.50 (3.00, 12.00)

Normal 5.00 (3.00, 9.00)

Overweight 4.25 (2.00, 8.00)

NS

Multivariate analysis NS

Hilson et al 1997 [12] USA, 1992–1994

Medical record review. Bassett Hospital, Cooperstown, NY Healthy singleton infant n = 1109

BMI calculated from pre-pregnancy weight and height

IOM definition of obesity

Exclusive breastfeeding:

Proportional hazards regression:

Overweight RR 1.42, p < 0.04

Obese 1.43, p < 0.02

Any breastfeeding:

Proportional hazards regression:

Overweight RR 1.68, p < 0.006

Obese 1.73, p < 0.001

(adjusted for maternal age, smoking, education, gestation, WIC, parity, birth weight, C. section, diabetes)

Hilson et al 2004 [42] USA, 1998

Bassett Hospital, Cooperstown, NY

Intended to bf, singleton infant. n = 114

BMI calculated from pre-pregnancy weight and height

IOM definition of obesity

Exclusive breastfeeding (wks, mean, sd)

Underweight/normal 3.6 (3.9)

Overweight 2.6 (3.2)

Obese 2.7 (2.3)

Any breastfeeding (wks, mean, sd)

Underweight/normal 7.3 (8.9)

Overweight 5.6 (5.4)

Obese 4.6 (4.6)

RR discontinuing bf: obese 2.43 (95%CI: 1.40, 4.20, p = 0.002) cf to underweight/normal wt women

Exclusive bf: NS

Multivariate analysis: RR = 2.03 (95%CI: 1.07, 4.5, p = 0.03)

(adjusted for infant feeding intention, work/school, satisfaction with appearance, indifference to bf)

Hilson et al 2006 [39] USA, 1988–1997

Expanded previous review of medical records [12].

Bassett Hospital, Cooperstown, NY

Intended to bf, singleton infant.

No contraindications to bf, no diabetes.

n = 2783

BMI calculated from pre-pregnancy weight and height

IOM definition of obesity

EBF = last time mother feed only breast milk, without adding non human milk, juice, solids

ABF = last feeding of any breast milk to infant

Median duration of EBF (wks):

Underweight 1.7

Normal 2.0

Overweight 1.7

Obese 1.1

p < 0.05

Median duration of ABF (wks):

Underweight 8.0

Normal 8.0

Overweight 7.0

Obese 2.0

p < 0.05

Multivariate analysis: HR of stopping bf:

Obese 1.50 (95%CI 1.11, 2.03) for normal wt gain in pregnancy

(adjusted for education, smoking, maternal age, parity, WIC, birth)

Kugyelka et al 2004 [40] USA, Hispanic women: 1998–2000; Black women: 1999–2000

Medical record review, upstate New York, all women of 'Hispanic ethnicity' (mainly Puerto Rican) (n = 235) or 'Black race' (n = 263) Healthy mothers who attempted to breastfeed with healthy single, term infant

BMI calculated from pre-pregnancy height and weight recorded on New York State prenatal form (could be measured or self-reported)

IOM definition of obesity

EBF = last time mother feed only breast milk, without adding non human milk ABF = last feeding of any breast milk to infant

Hispanic women:

Obesity assoc with shorter duration of EBF (RR: 1.5; 95%CI: 1.1, 2.0) and ABF (RR: 1.6; 95%CI: 1.1, 2.1) compared to normal wt women

Black women:

No effect of BMI on duration of EBF or ABF

Li et al 2002 [83] USA 1988–1994 (exclusive bf: Phase II, 1991–1994)

The Third National Health and Nutrition Survey (NHANES III) n = 7712

BMI calculated from self-reported ht and wt at time of interview

WHO definition of obesity

Exclusive breastfeeding at 2 months:

Normal 35.4%

Overweight 28.2%

Obese 25.9%

Breastfeeding at 6 months:

Normal 25.0%

Overweight 17.3%

Obese 16.9%

Breastfeeding at 12 months:

Normal 10.0%

Overweight 5.7%

Obese 5.6%

Li et al 2003 [49] USA 1996–1998

Pediatric Nutrition Surveillance System and the Pregnancy Nutrition Surveillance System Children aged < 5 years n = 124,151 (n for multivariate analysis of women who initiated breastfeeding = 13,234)

BMI calculated from self-reported pre-pregnancy weight

IOM definition of obesity

Adjusted breastfeeding duration (weeks):

Underweight 13.3

Normal weight 13.6

Overweight 13.1

Obese 11.8

(p < 0.01)

(adjusted for gestational weight gain, birth weight, gestation, parity, maternal age, education, marital status, race, smoking, prenatal care, poverty-income ratio)

Oddy et al 2006 [44] Australia 1989–1991

Western Australian Pregnancy Cohort Study. Antenatal cohort, King Edward Memorial Hospital, Perth, WA n = 1803

BMI calculated from pre-pregnancy weight and height (measured by research midwives) WHO definition of obesity

Breastfeeding < 2 months:

Normal weight 24.0%

Overweight 33.6%

Obese women 41.6%

p < 0.0005

Breastfeeding < 4 months:

Normal weight 37.9%

Overweight 50.2%

Obese women 57.5%

p < 0.0005

Breastfeeding < 6 months:

Normal weight 49.0%

Overweight 59.7%

Obese women 62.8%

p = 0.001

Multivariate Cox hazards regression model:

HR (adj) = 1.18 (95%CI 1.05, 1.34) for breastfeeding per month (adjusted for education, maternal age, pregnancy problems, older siblings, smoking, solids before 4 months).

Rutishauser & Carlin 1992 [11] Australia 1984–1985

Primiparas breastfeeding > 14 days Barwon region, Victoria n = 739

(N for multivariate analysis between 570 and 600)

BMI calculated from maternal ht and wt recorded at 1 month postpartum Normal = BMI < 26, Above normal = BMI > 26

Duration of breastfeeding associated with BMI (p < 0.05)

Multivariate analysis (Cox proportional hazards):

HR 1.50 (95%CI 1.11, 2.04)

(adjusted for smoking, maternal age, time to first breastfeed)

Scott et al 2006 [84] Australia 2002–2003

2^nd Perth Infant Feeding Study, cohort of women recruited in hospital. n = 587

Measurement of maternal weight and height not reported

WHO definition of obesity

Any breastfeeding at 6 months (other time periods also given):

Normal 49.0, sd 5.2

Overweight 48.3, sd 9.5

Obese: 35.7, sd 10.1

p < 0.05

Multivariate analysis NS