Maternal iron intake at mid-pregnancy is associated with reduced fetal growth: results from Mothers and Children’s Environmental Health (MOCEH) study

Abstract

BackgroundIron supplementation is a common recommendation for pregnant women to prevent iron deficiency during pregnancy. There is an increasing concern about excessive iron consumption as a general iron prophylaxis by pregnant women without any due consideration about their dietary iron intake or iron status. Our present study investigated the association between total iron intake from diet and supplements and fetal growth in 337 pregnant women at mid-pregnancy in South Korea.MethodsIron intake from diet and supplements was examined by a 24-hour recall method. Subjects were divided into three groups based on tertiles of total iron intake levels. Fetal biometry was assessed by ultrasonography at mid-pregnancy.ResultsAbout 99% of the non-supplement users had iron intake below the recommended nutrient intake (RNI) for pregnant women (24 mg), whereas 64.9% of supplement users had iron intake above the upper level (UL) (45 mg). In the babies of mothers in the third tertile of iron intake (>17.04 mg), biparietal diameter, abdominal circumference, and femur length were lower by 0.41 cm (P =0.019), 0.41 cm (P = 0.027), and 0.07 cm (P = 0.051), respectively, than the babies of mothers in the second tertile of iron intake (11.49 ~ 17.04 mg).ConclusionThese results suggest that excessive maternal iron intake at mid-pregnancy is associated with reduced fetal growth. Iron supplementation for pregnant women should be individualized according to their iron status. Appropriate diet education is needed for pregnant women so that they can consume adequate amounts of iron from food and supplements.

Maternal intake of omega-3 and omega-6 polyunsaturated fatty acids during mid-pregnancy is inversely associated with linear growth

“…It is also possible that our findings stem from the inverse correlation between intake of PUFA and intake of animal and dairy products during the second trimester. Given that animal-based foods contain key nutrients for fetal growth and development (e.g., protein, calcium, iron and zinc [40][41][42] ), our observed associations may be due to lower maternal intake of animal-based food, which have been previously related to higher to fetal growth and size at birth, 43 rather than higher intake of PUFA. The fact that we detected associations with second and third trimester, but not first trimester, is likely related to the fact that midpregnancy is a critical period for linear growth since peak length gain velocity occurs by 20 weeks.…”

Diet and Lifestyle Before and During Pregnancy – Practical Recommendations of the Germany-wide Healthy Start – Young Family Network

“…Iron supplementation in pregnancy improves maternal status and protects against anaemia; however, as regards the benefit to the child of general supplementation of all pregnant women, the data are inconclusive 123 , 124 , 125 . In addition, there is evidence that additional iron intake in well-supplied pregnant women can increase the risk of premature births and low birth weight 126 , 127 . Against this background, general prophylactic iron supplementation is not recommended for pregnant women in Germany.…”

Maximising benefits and minimising adverse effects of micronutrient interventions in low- and middle-income countries

“…In iron-replete infants and young children, exposure to iron fortified foods has been associated with decreased growth (54,55) , impaired cognitive development (56,57) and increased diarrhoea possibly due to altered gut microbiota to more pathogenic bacteria (58,59) . In pregnant women, there is emerging evidence that suggest that high iron status as reflected by high haemoglobin or serum ferritin values can be associated with adverse effects including preterm birth, impaired fetal growth and gestational diabetes (60)(61)(62)(63)(64)(65) . More research in this area is urgently needed to better understand the emerging evidence coming largely from observational studies.…”