Infant growth and health outcomes associated with 3 compared with 6 mo of exclusive breastfeeding.
BACKGROUND
Opinions and recommendations about the optimal duration of exclusive breastfeeding have been strongly divided, but few published studies have provided direct evidence on the relative risks and benefits of different breastfeeding durations in recipient infants.


OBJECTIVE
We examined the effects on infant growth and health of 3 compared with 6 mo of exclusive breastfeeding.


METHODS
We conducted an observational cohort study nested within a large randomized trial in Belarus by comparing 2862 infants exclusively breastfed for 3 mo (with continued mixed breastfeeding through >/= 6 mo) with 621 infants who were exclusively breastfed for >/= 6 mo. Regression to the mean, within-cluster correlation, and cluster- and individual-level confounding variables were accounted for by using multilevel regression analyses.


RESULTS
From 3 to 6 mo, weight gain was slightly greater in the 3-mo group [difference: 29 g/mo (95% CI: 13, 45 g/mo)], as was length gain [difference: 1.1 mm (0.5, 1.6 mm)], but the 6-mo group had a faster length gain from 9 to 12 mo [difference: 0.9 mm/mo (0.3, 1.5 mm/mo)] and a larger head circumference at 12 mo [difference: 0.19 cm (0.07, 0.31 cm)]. A significant reduction in the incidence density of gastrointestinal infection was observed during the period from 3 to 6 mo in the 6-mo group [adjusted incidence density ratio: 0.35 (0.13, 0.96)], but no significant differences in risk of respiratory infectious outcomes or atopic eczema were apparent.


CONCLUSIONS
Exclusive breastfeeding for 6 mo is associated with a lower risk of gastrointestinal infection and no demonstrable adverse health effects in the first year of life.
Kramer
Michael S
MS
Department of Pediatrics, McGill University Faculty of Medicine, Montreal. michael.kramer@mcgill.ca
Guo
Tong
T
Platt
Robert W
RW
Sevkovskaya
Zinaida
Z
Dzikovich
Irina
I
Collet
Jean-Paul
JP
Shapiro
Stanley
S
Chalmers
Beverley
B
Hodnett
Ellen
E
Vanilovich
Irina
I
Mezen
Irina
I
Ducruet
Thierry
T
Shishko
George
G
Bogdanovich
Natalia
N
D000328:Adult; D001942:Breast Feeding; D015331:Cohort Studies; D004522:Educational Status; D005260:Female; D005767:Gastrointestinal Diseases / Q000453:epidemiology / Q000517:prevention & control; D006128:Growth; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D012141:Respiratory Tract Infections / Q000453:epidemiology / Q000517:prevention & control; D013997:Time Factors; D015430:Weight Gain