A number of lifestyle factors are associated with preterm births and foetal growth restrictions including cigarette smoking, black race, a low body mass index (BMI) and nulliparity. Preterm births and growth restrictions are of concern because they considerable increase the risk of neonatal death. Evidence suggests that poor nutrition is also a major factor in increasing the risk of pregnancy problems and the risk of premature neonatal deaths, and that improving the micronutrient content of the diet through use of a multivitamin and mineral formula may be beneficial. For example, it is well known that pregnant women are recommended to take an additional supplement of folic acid in order to prevent neural tube defects in the developing foetus. Because vitamins and minerals require time to improve health, it is suggested that long-term use of a multivitamin and mineral formula before conception, would provide the best benefit.
Researchers1 have investigated the use of multivitamin and mineral supplements for associations with small-for-gestational-age (SGA) and preterm births in a cohort of 35,897 Dutch women. Women were asked to report the number of weeks of multivitamin and mineral formula use and then Cox regression was used to estimate the association between the use of the supplement and the risk of preterm births. The results showed that the effect a multivitamin and multimineral formula had on birth outcomes was dependent on the weight status of the mother. Use of a multivitamin and multimineral formula in non-overweight women (<25kg/m2) was associated with a 16% reduced risk of preterm births and labour. However, in overweight women, there was no such association. The risk of a SGA birth was reduced with multivitamin and mineral use regardless of the BMI of the mother during and before pregnancy (hazard ratio 0.83).
The contents of the most popular multivitamin and mineral formula used in the study are shown in figure 1. There is always a difficulty with interpretation of the data as presented here, because those who use multivitamin and mineral formulas tend to have healthier lifestyles compared to those who do not supplement. Therefore unmeasured factors may cofound these results. Other studies have found that preconcenptional vitamin use is beneficial in improving pregnancy outcomes. For example one study has shown that sufficient periconceptional vitamin B6 and B12 intakes are associated with a 50 to 60% reduction in preterm births. Just why overweight status should modify the outcomes of the association between multivitamin and mineral use and preterm births in not clear. However, it is possible that sequestration of the micronutrients into the larger adipose tissue pool in overweight subjects may play a role in this effect.
Figure 1. The content of the most popular multivitamin and mineral formula taken by the women in the study1.
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