Maternal iron supplementation in pregnancy and asthma in the offspring: follow-up of a randomised trial in Finland

Maternal iron status during early pregnancy and school‐age, lung function, asthma, and allergy: The Generation R Study

“…anemia. 10 Differences with our results might be due differences in the populations, a selected or mono-ethnic population versus our multi-ethnic population, timing of iron status assessment in pregnancy, higher ferritin levels at baseline, and potential unmeasured confounders in our population. Additionally, it could be that only maternal iron deficiency below a certain threshold affects child's respiratory and allergy outcomes.…”

“…In a Mendelian randomization study among 6002 subjects, maternal genetic proxies for a lower iron status were associated with a lower school age FEV 1 and FVC, but only in children whose mothers did not receive iron supplementation in late pregnancy, and not in case of asthma or inhalant allergic sensitization 8 . A follow‐up of a randomized controlled trial, limiting unmeasured and residual confounding, found that children of mothers who received routine supplementation of 100 mg iron per day had a lower risk of an asthma diagnosis between 10 and 32 years of age, as compared to children of mothers who received only two times a day 50 mg of iron supplementation if the mother was diagnosed with anemia 10 . Differences with our results might be due differences in the populations, a selected or mono‐ethnic population versus our multi‐ethnic population, timing of iron status assessment in pregnancy, higher ferritin levels at baseline, and potential unmeasured confounders in our population.…”

“…In addition, we previously found a relation of higher maternal hematocrit concentrations during pregnancy with a lower lung function 9 . A randomized control trial showed that, as compared to selective iron supplementation, routine maternal iron supplementation during pregnancy reduced the risk of asthma diagnosis in the children 10 . However, the number of studies on maternal iron status during pregnancy with childhood respiratory and allergy outcomes are scarce, small sample‐sized, used genetic variants or hematocrit as a proxy for maternal iron status, or were limited in asthma diagnosis ascertainment.…”

“…9 A randomized control trial showed that, as compared to selective iron supplementation, routine maternal iron supplementation during pregnancy reduced the risk of asthma diagnosis in the children. 10 However, the number of studies on maternal iron status during pregnancy with childhood respiratory and allergy outcomes are scarce, small sample-sized, used genetic variants or hematocrit as a proxy for maternal iron status, or were limited in asthma diagnosis ascertainment. Therefore, the present study aimed to examine among 3825 children and their mothers participating in a populationbased prospective cohort study, the associations of maternal iron status during early pregnancy with lung function, asthma, inhalant allergic sensitization, and physician-diagnosed inhalant allergy in school-aged children.…”

The Role of Nutritional Factors in Asthma: Challenges and Opportunities for Epidemiological Research

“…Evidence for a protective role of maternal intake of vitamins E and D, zinc, fruits, vegetables, omega-3 polyunsaturated fatty acids (PUFAs) or an overall healthy diet (assessed using the Mediterranean diet score or a negative DII score) during pregnancy has been found with regard to the risk of wheezing in the first years of life [45][46][47][48][49][50], but evidence for a lower risk of actual asthma, or even wheezing later in childhood, is lacking [45][46][47][48]51,52]. Recent studies have suggested a protective effect of maternal iron supplementation [53] and deleterious effects of high maternal free sugar, fructose and sugar-sweetened beverage (SSB) intake [54,55] and of a pro-inflammatory diet [56] during pregnancy on asthma development in mid-or late-childhood.…”