Dietary diversity, socioeconomic status and maternal body mass index (BMI): quantile regression analysis of nationally representative data from Ghana, Namibia and Sao Tome and Principe.
OBJECTIVE
To (a) assess the association between dietary diversity (DD) score, socioeconomic status (SES) and maternal body mass index (BMI), and (b) the variation of the effects of DD and SES at different points of the conditional distribution of the BMI.


METHODS
The study used Demographic and Health Surveys round 5 data sets from Ghana, Namibia and Sao Tome and Principe. The outcome variable for the analysis was maternal BMI. The DD score was computed using 24-hour dietary recall data. Quantile regression (QR) was used to examine the relationship between DD and SES, and maternal BMI, adjusting for other covariates. The QR allows the covariate effects to vary across the entire distribution of maternal BMI.


RESULTS
Women who consumed an additional unit of DD achieved an increase of 0.245 in BMI for those in the 90th quantile in Ghana. The effect of household wealth increases for individuals across all quantiles of the BMI distribution and in all the 3 countries. A unit change in the household wealth score was associated with an increase of 0.038, 0.052 and 0.065 units increase in BMI for individuals in the 5th quantile in Ghana, Namibia and Sao Tome and Principe, respectively. Also, 0.237, 0.301 and 0.174 units increased for those in the 90th quantile in Ghana, Namibia and Sao Tome and Principe, respectively. Education had a significant positive effect on maternal BMI across all quantiles in Namibia and negative effect at the 5th, 10th and 90th quantiles in Sao Tome and Principe.


CONCLUSIONS
There is heterogeneity in the effects of DD and SES on maternal BMI. Studies focusing on the effects of diet and socioeconomic determinants on maternal BMI should examine patterns of effects at different points of the conditional distribution of the BMI and not just the average effect.
African Population and Health Research Center, Nairobi, Kenya.
Dickson A
DA
Amugsi
African Population and Health Research Center, Nairobi, Kenya.
Zacharie T
ZT
Dimbuene
African Population and Health Research Center, Nairobi, Kenya.
Pauline
P
Bakibinga
African Population and Health Research Center, Nairobi, Kenya.
Elizabeth W
EW
Kimani-Murage
African Population and Health Research Center, Nairobi, Kenya.
Tilahun Nigatu
TN
Haregu
African Population and Health Research Center, Nairobi, Kenya.
Blessing
B
Mberu
PUBLIC HEALTH
Eur J Clin Nutr. 1994 Nov;48 Suppl 3:S45-53; discussion S53-5
7843160
Soc Sci Med. 2006 Nov;63(10):2533-45
16876925
Am J Clin Nutr. 2006 Sep;84(3):633-40
16960179
Proc Nutr Soc. 2008 Feb;67(1):105-8
18234138
Public Health Nutr. 2008 Feb;11(2):132-41
17565760
Lancet. 2013 Aug 3;382(9890):427-51
23746772
Am J Clin Nutr. 2011 Feb;93(2):413-21
21068343
Eur J Clin Nutr. 1994 May;48(5):349-57
8055851
Obes Rev. 2012 Nov;13(11):1067-79
22764734
J Nutr. 2006 Oct;136(10):2625-32
16988137
J Biosoc Sci. 1993 Jan;25(1):31-8
8425883
Eur J Clin Nutr. 2006 Jul;60(7):815-22
16452917
BMJ. 2000 Nov 25;321(7272):1311-5
11090512
Nephrol Dial Transplant. 2008 Jan;23(1):47-51
17890752
Public Health Nutr. 2007 Jan;10(1):71-8
17212836
Eur J Clin Nutr. 1994 Nov;48 Suppl 3:S141-7
7843151
Eur J Clin Nutr. 2005 May;59(5):703-16
15867942
Public Health Nutr. 2000 Mar;3(1):39-47
10786722
Lancet. 2008 Jan 19;371(9608):243-60
18207566
J Nutr. 2013 Jul;143(7):1176-83
23658424