Effects of prolonged and exclusive breastfeeding on child height, weight, adiposity, and blood pressure at age 6.5 y: evidence from a large randomized trial.
BACKGROUND
The evidence that breastfeeding protects against obesity and a variety of chronic diseases comes almost entirely from observational studies, which have a potential for bias due to confounding, selection bias, and selective publication.


OBJECTIVE
We assessed whether an intervention designed to promote exclusive and prolonged breastfeeding affects children's height, weight, adiposity, and blood pressure at age 6.5 y.


METHODS
The Promotion of Breastfeeding Intervention Trial (PROBIT) is a cluster-randomized trial of a breastfeeding promotion intervention based on the WHO/UNICEF Baby-Friendly Hospital Initiative. A total of 17,046 healthy breastfed infants were enrolled from 31 Belarussian maternity hospitals and their affiliated clinics; of those infants, 13,889 (81.5%) were followed up at 6.5 y with duplicate measurements of anthropometric variables and blood pressure. Analysis was based on intention to treat, with statistical adjustment for clustering within hospitals or clinics to permit inferences at the individual level.


RESULTS
The experimental intervention led to a much greater prevalence of exclusive breastfeeding at 3 mo in the experimental than in the control group (43.3% and 6.4%, respectively; P < 0.001) and a higher prevalence of any breastfeeding throughout infancy. No significant intervention effects were observed on height, body mass index, waist or hip circumference, triceps or subscapular skinfold thickness, or systolic or diastolic blood pressure.


CONCLUSIONS
The breastfeeding promotion intervention resulted in substantial increases in the duration and exclusivity of breastfeeding, yet it did not reduce the measures of adiposity, increase stature, or reduce blood pressure at age 6.5 y in the experimental group. Previously reported beneficial effects on these outcomes may be the result of uncontrolled confounding and selection bias.
Department of Pediatrics, McGill University Faculty of Medicine, Montreal, PQ, Canada. michael.kramer@mcgill.ca
Michael S
MS
Kramer
Lidia
L
Matush
Irina
I
Vanilovich
Robert W
RW
Platt
Natalia
N
Bogdanovich
Zinaida
Z
Sevkovskaya
Irina
I
Dzikovich
Gyorgy
G
Shishko
Jean-Paul
JP
Collet
Richard M
RM
Martin
George
G
Davey Smith
Matthew W
MW
Gillman
Beverley
B
Chalmers
Ellen
E
Hodnett
Stanley
S
Shapiro
D050154:Adiposity / Q000502:physiology; D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D001824:Body Constitution / Q000502:physiology*; D001827:Body Height / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D001942:Breast Feeding; D002648:Child; D002657:Child Development / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D002094:Republic of Belarus