The daily requirements of nutritional iodine increase immensely during pregnancy to supply the demands of the growing foetus as well as the increase in iodine clearance by the kidney . Therefore, insufficient iodine intake in women, especially during pregnancy, represents a major worldwide health concern . To the best of our knowledge, this study is the first to measure iodine adequacy in a cohort of reproductive age Saudi women and the results were compared between the pregnant and non-pregnant participants. The data showed that the median of 24-hr UIE in the non-pregnant population was at the lowest recommended limit, whereas it was markedly inferior in the pregnant women than the minimal cut-off for iodine sufficiency advocated by the WHO . Although the majority of non-pregnant (73%; n = 292/400) and pregnant women (71.5%; n = 874/1222) reported the use of iodised salt, the rates of iodine deficiency were 49.7% (n = 199) and 62.5% (n = 764), respectively. Moreover, only 2.8% of the non-pregnant and 27.6% of the pregnant women were using iodine supplements.
The currently available reports regarding iodine nutritional state among the Saudi population are controversial and national surveys are rare. The general Saudi public is considered by the latest IGN report in 2019 as iodine sufficient based on the findings of a 2012 national survey of SAC [5, 16]. Additionally, another study that included 311 SAC enrolled from a previously reported severe iodine deficient region in the Southwestern of KSA showed a significant enhancement in iodine status following the implementation of salt iodisation program . Conversely, a more recent report from the same geographical region has revealed in 2015 severe iodine deficiency (median UIC 17 μg/L) in 3046 SAC among whom 24% had goitre . Another study on 1887 SAC from Al-Taif city in Makkah province has also demonstrated a rate of 71% for nutritional iodine deficiency (median UIC 84 μg/L) and 7.4% of the study population were goitrous . Coherently, a more recent national survey has shown that 70% of the Saudi households were using iodised salt, which does not meet the target of 90% set by the WHO . Additionally, we have previously reported 26.8% hypothyroidism and 4.8% isolated hypothyroxinaemia in 500 pregnant Saudi women from the Western region . The present study correlates with the prior reports that have underscored the magnitude of iodine deficiency in several regions of KSA, including Makkah province, as well as thyroid disorder in pregnant women [24–27].
Our results also suggest that the Saudi women of childbearing age, at least in the Western region, appear to suffer from mild to moderate iodine deficiency and the rates could increase significantly during pregnancy. Additionally, this study provides further support to the notion that the levels of UIC in SAC may not accurately reflect iodine status for pregnant women [7–11]. In consolidation, the IGN has revealed that 29 countries have reported iodine deficiency in pregnant women, whereas their SAC population was sufficient . Studies from the United States have also demonstrated a significant increase in the rates of iodine insufficiency among pregnant women despite the use of iodised salt . Furthermore, a research group from Austria has similarly reported that 86.3% of 246 pregnant women were iodine insufficient even with the use of iodised salt and/or iodine supplements . Coherently, the median of estimated 24-hr UIE in a Danish pregnant population was below the WHO limits with or without the use of daily supplements containing 175 μg/L of iodine . More recently, another Israeli group has exposed that the median UIC was 61 μg/L in 1074 pregnant women and 85% of them were classified as iodine insufficient . Likewise, a study from a Chinese province with iodine adequacy following the implementation of salt iodisation has shown that 50% of the enrolled 8159 pregnant women had iodine insufficiency . Taken together, our study and the earlier reports advocate that the health authorities in each country should consider measuring iodine intake in women of reproductive age independently from SAC to precisely estimate the deficiency rates in this vulnerable group [7–11]. Furthermore, educational programs should be developed to increase the awareness of women of childbearing age, especially those who are pregnant or planning for pregnancy, about the significance of iodine for them as well as for their offspring wellbeing [34, 35].
The status of nutritional iodine could be influenced by numerous factors in reproductive age women [36–38]. Herein, the risk of developing iodine deficiency was highest during the first trimester of pregnancy. Although the risk decreased as pregnancy progressed, women in the 2nd and 3rd trimesters showed > 3.5-fold increase in the risk of iodine inadequacy. In harmony, a recent Irish study has equally unveiled that the median of UIC was significantly lowest during the first trimester and despite an increase in the urine levels during the following trimesters, the UIC remained markedly below the WHO recommended levels . An explanation for the observed higher risk of iodine deficiency during the first trimester could also be related to inappropriate nutrition intake due to loss of appetite and/or increase vomiting . Several studies conducted among the Saudi population have also indicated that most of pregnant women were malnourished and their consumption of essential nutrients were below the recommended daily requirements [41–44]. Saudi women from the Western region had also significantly lower intake of micronutrients during the first trimester, thus their offspring had an increased risk of developing birth defects [45–47]. Our findings agree with the earlier observations since they showed that only 27.6% of the enrolled pregnant population were using iodine supplements, which was associated with significantly lower risk of developing iodine deficiency during pregnancy. Accordingly, this study reinforces the many calls for improving awareness regarding the importance of iodine intake from dietary and/or supplement sources, especially at the early stages of pregnancy [39, 48–50].
The present results also revealed that the pregnant women consuming non-iodised salt had a 2-fold increase in the risk of developing inadequate iodine intake, whereas they showed > 50% decrease in the risk of taking iodine above their requirements during pregnancy. The WHO and UNICEF have adopted the USI policy since 1994 to ensure that the general public adequately consume sufficient iodine . Although the salt iodisation is implemented in KSA, the household consumption of iodised salt (70%) was found to be lower than the WHO recommendations of 90% usage by the general population to avoid iodine deficiency . More recently, the WHO has also recommended salt reduction to 5 gram/day for adults, including pregnant and lactating women, to lessen the likelihood of developing hypertension and heart diseases . Suggested plans to simultaneously maintain iodine adequacy with decreasing salt intake include fortifying salt with higher amounts of iodine . Alternatively, Australia and New Zealand have adopted a different strategy by fortifying bread to ensure the delivery of adequate iodine and several studies have reported that the median UIC in adults, including pregnant women, met the WHO recommended intervals post-fortification [52, 53]. Therefore, the reported lower use of iodised salt in KSA as well as the advised reduction of salt intake accentuate the importance of developing other vehicle(s) for iodine to decrease the incidence of iodine deficiency disorders [52, 53]. Furthermore, women of reproductive age (150 µg/day) and pregnant women (250 µg/day) could benefit from daily iodine supplements as a temporarily method till developing a solid and effective national salt/bread iodisation program [26, 52, 53].
The present study also showed a weak positive association between BMI and UIC, which correlates with previous reports from Bangladesh and Romania [54, 55]. A possible explanation could be that pregnant and non-pregnant women with high BMI were consuming higher foods rich in iodine than lean individuals. Additionally, pregnant women often change their dietary habits and eat more fish and milk, the richest sources of iodine, and the tendency for consuming these foods is higher in obese than lean women . Opposingly, several other studies either have reported negative association between BMI and UIC [9, 57] or have shown no correlation between body weight and iodine intake [8, 39]. These discrepancies between the studies could be linked to differences in eating habits and dietary patterns between the different populations as well as between cities of each country [58, 59].
There are several limitations for your study. Although the number of participants is larger compared with several other reports on pregnant women [7–9], our study participants were enrolled only from a single site. Additionally, we did not measure the dietary intake and the thyroid function parameters to correlate them with the iodine status in the study population. However, this is a phase 1 study and we have plans to conduct further research with a special focus on pregnant women to measure the interactions between nutritional habits, thyroid functions and iodine intake.