Prevention of intrauterine growth retardation by food supplementation in rural Burkina Faso

Ondertitel:Preventie van intra-uteriene groeiachterstand door middel van voedingssupplementatie in ruraal Burkina Faso

Infants born with a low birth weight are at higher risk of neonatal morbidity and mortality, and possibly chronic diseases in adulthood. In developing countries it was found that low birth weight was mainly caused by intrauterine growth retardation. Maternal nutrition is widely recognised as a key determinant for optimal foetal development, which ultimately results in a higher birth weight. However, at present nutritional intervention studies during pregnancy showed only modest and sometimes conflicting results regarding their effect on birth size. A possible explanation could be that the previous nutritional interventions addressed only partially the additional nutritional needs during pregnancy. Therefore a randomised controlled trial in the rural health district of Houndé, Burkina Faso, was conducted to evaluate the effect of a balanced energy/protein (<25% of the energy from protein) fortified food supplement (FFS) enriched with multiple micronutrients on birth size. We compared this supplementation with a control group of mothers receiving a daily multiple micronutrients supplement (MMN). Dietary supplementation, however, is not an isolated intervention and is expected to interact with the dietary intake during pregnancy. Therefore, dietary assessment studies were performed to assess, first, the influence of pregnancy on dietary intake and, second, to study the effects of the used food supplement on the daily diet of the participating pregnant women. In order to study the dietary intake of mothers in rural Sub-Saharan Africa, validated tools to obtain accurate estimates of the consumed portion sizes of staple foods are essential. In affluent countries, good results were obtained using food photographs for this purpose. Chapter 3 presents the results of a validation study of food photographs of the most frequently consumed dishes, to be used in 24h dietary recall study of pregnant women in a rural Burkina. A food photograph album containing four photographs of food portions per food item was compiled for eight selected food items. Subjects (n = 257) were presented two food items each in the morning and two in the afternoon. These foods were weighed to the exact weight of one of the photos in the same recipients as depicted on the photographs. The day after another field worker presented the food photographs to the subjects to test their ability of choosing the correct photograph. The results of this study showed that the correct photo out of the four proposed, was chosen in 55% of 1028 estimations. On a group level, mean differences between served and estimated portion sizes were between -8.4% and 6.3%. These results indicated that in a West-African rural setting, food photographs can be a valuable tool for the quantification of food portion size on group level. While nutritional requirements increase during pregnancy, it was previously reported in other developing countries that future mothers restricted their dietary intake due to cultural beliefs. Chapter 4 presents the results of two studies: a qualitative study, including in-depth interviews, was undertaken in sample of 37 pregnant women to analyse specific perceptions and attitudes regarding food consumption during pregnancy. In addition, an interactive 24-h dietary recall survey was used to compare the food intake of 218 pregnant and 176 non-pregnant women to verify the effect of possible pregnancy-related modified dietary behaviours. The results of these studies indicated the existence of dietary restrictions during pregnancy but no consistent pattern of avoided food types was found. Most of the mentioned ‘forbidden’ foods were related to physical discomfort during gestation. Interviewees also admitted to ignoring culturally determined food prohibitions/prescriptions. The results of the quantitative food intake study, however, showed no differences food intake, food choice and nutrient intake between the group of pregnant and non-pregnant women. Therefore, it was concluded that, although the knowledge of pregnancy-related food beliefs exist, pregnant women in this rural area of Burkina Faso did not seem to modify their dietary intake as compared with non-pregnant women. The additional nutritional requirements of pregnancy are not accounted for in their dietary practises. Chapter 5 presents the results of a second cross-sectional dietary assessment study evaluating the food and nutrient intake of women participating in the RCT. The aim of this study was to assess if the introduction of energy-dense FFS (372 kcal per day) would lead to dietary substitution in the participant’s daily diet. The usual dietary intake of 128 pregnant women receiving a daily food supplement was compared to the diet of 132 pregnant women receiving a daily multiple micronutrient tablet by multiple 24h-dietary recalls. The study could not find any difference in food group consumption between women receiving FFS or MMN. Moreover, on nutrient level, it was shown that the provided FFS was not compensated for by the home diet, thus resulting in a net increment of energy intake by 406 kcal (P < 0.001) for mothers receiving daily FFS. This study provided evidence that the evaluated energy-dense fortified food supplement is able to provide an additional nutritional support to pregnant women and thus suitable for a controlled intervention study. In Chapter 6 the results of the main intervention study are presented and discussed. It was hypothesized that providing FFS would result in a higher birth weight and birth length than would a daily MMN supplementation alone. Between 2006 and 2008, a non-blinded, individually randomised controlled trial was conducted including 1296 pregnant women from 2 health sectors in the rural sanitary district of Houndé, Burkina Faso. Supplements were provided on a daily basis, and compliance was closely verified by using a community-based network of home visitors. Anthropometric measures at birth were available for analysis for 87% of the 1175 live singleton deliveries enrolled. After adjustment for gestational age at birth, the FFS group had a significantly higher birth length (+4.6 mm; P = 0.001). FFS supplementation resulted in a modestly higher birth weight (+31 g; P = 0.197). Also, placental weight was found higher in the FFS group (15.6; P = 0.044). Subgroup analyses showed clinically important treatment effects on birth length (+12.0 mm; P = 0.005) and on birth weight (+111 g; P = 0.133) for underweight [body mass index (in kg/m²) <18.5] pregnant women. Women with early pregnancy anaemia who received FFS gave birth to taller newborns (+7.3 mm; P = 0.002) than did those who received MMN supplementation. In conclusion, this study demonstrated that prenatal supplementation with FFS resulted in taller infants than did MMN supplementation. For women with a sub-optimal pre-pregnancy nutritional status, MMN supplementation should be complemented with a balanced energy and protein supplement to produce a clinical effect on birth size. The results from the intervention study showed that prenatal FFS increased birth length and placental weight. Insulin, Insulin-like growth factors (IGF) and their binding proteins are known to influence foetal and placental growth. In Chapter 7, results from a sub-study are presented that compared the effect of prenatal FFS with MMN supplementation on cord hormone concentrations in a sub-sample of the randomised controlled trial as presented in Chapter 6. Insulin-like growth factors I (IGF-I) and II (IGF-II), their binding proteins IGFBP-1 and IGFBP-3, leptin, cortisol and insulin were quantified in cord sera in a random sub-sample of 205 singleton pregnancies. The results did not demonstrate that there was no overall effect of FFS, relative to MMN, on the analysed cord hormone concentrations. However, sub-group analysis showed that cord blood leptin was significantly higher in primigravidae, but not in multigravidae, receiving FFS. Also mothers with a higher mid-upper arm circumference at study inclusion who received FFS had higher cord leptin concentrations. The observed changes in cord leptin coincided with changes in ponderal index at birth which suggests that the observed changes in cord leptin are associated with changes in body composition at birth. In conclusion, it could not be demonstrated that the previously observed effect of prenatal FFS on birth length or placental weight was mediated by changes in cord hormone concentrations. The causality of the observed association between cord leptin and possibly modified foetal body composition in function of maternal diet warrants confirmation by further research. In conclusion, this PhD research added to the present evidence on the effect of maternal nutrition on foetal growth in a rural Sub-Sahara African setting. In Chapter 8 the importance of the findings are discussed and some recommendations for further research are formulated. Follow-up studies of the infants that were born in the framework of this research will elucidate further the importance of the present results.

ISBN:9789059893580

Jaar van publicatie:2010

Toegankelijkheid:Closed