The available reports regarding iodine status in the Saudi population are scarce, their results are controversial, and none investigated iodine adequacy among vulnerable groups, including pregnant women. To the best of our knowledge, this study is the first to measure iodine adequacy in reproductive age and pregnant Saudi women. The data showed that the majority of non-pregnant women (73%) were using iodised salt, 2.8% were using iodine supplements, and the median UIC was at the lowest WHO recommended limit for iodine adequacy in reproductive age women . In contrast, the pregnant group median UIC was below the WHO minimal level for iodine sufficiency despite that iodised salt and/or daily iodine supplements were used by 71.5% and 27.6% of the participants, respectively. Our findings infer that the reproductive age Saudi women were marginally iodine sufficient, while the pregnant population had mild deficiency that could denote a public health burden [25-28].
The IGN report (2019) has classified the general Saudi public as iodine sufficient based on the outcomes of a 2012 national SAC survey [5, 16]. Others also showed an enhancement of SAC iodine status after the execution of USI in the Southwestern of KSA, a previously classified severe iodine deficient region . Contrariwise, a research group has disclosed severe iodine deficiency (median UIC 17 μg/L) in 3046 SAC from the same region, and 24% of the children had goitre . Moderate iodine deficiency (median UIC 84 μg/L) has also been reported in 1887 SAC from Makkah province, and 7.4% of the participants were goitrous . Another national survey has shown that 69% of local salt samples were adequately iodised (15 – 40 ppm). Nevertheless, only 70% of the Saudi households were using iodised salt, which did not reach the USI target of ≥ 90% coverage . The present study is aligned with the prior national studies proclaiming iodine adequacy in the general Saudi population since the non-pregnant women were iodine sufficient [5, 16, 34]. However, the levels were at the lowest margin of adequacy, thus providing additional sustenance for the prior demands to ban non-iodised salt in order to enhance iodine intake in KSA .
On the other hand, mild iodine deficiency was detected in our pregnant population across the different trimesters. The daily iodine requirements increase immensely during pregnancy to supply the demands of growing foetus as well as to compensate the physiological increase in iodine renal excretion . An explanation for the observed iodine deficiency in our study could be related to inappropriate nutrition during prengancy as many studies have indicated that most of Saudi pregnant women were malnourished, and their consumption of essential nutrients were below the recommended daily requirements [35-38]. Saudi women from the Western region also had significantly low micronutrients intake, thus their offspring had a higher risk of developing birth defects [39-41]. Our findings agree with the earlier studies since the use of iodine supplements was only confirmed by a minority (27.6%) of the enrolled pregnant population. Accordingly, this study reinforces the many calls for improving awareness regarding the importance of iodine intake from dietary and supplement sources during pregnancy [42-45]. Moreover, iodine insufficiency during pregnancy could precipitate maternal thyroid disorders alongside poor foetal neurodevelopment [1-4]. We have previously reported that 26.8% and 4.8% of 500 pregnant Saudi women from the Western region had hypothyroidism and isolated hypothyroxinaemia, respectively . However, little is currently known in KSA about the links between iodine intake and thyroid diseases during pregnancy. Hence, more studies to measure the associations between iodine status and thyroid hormones in pregnant Saudi women are still needed.
Additionally, this study further supports the notion that SAC median UIC could be an imprecise approach for estimating iodine status in pregnant women [7-11]. In consolidation, The IGN has revealed that 29 countries reported iodine deficiency in pregnant women, whereas their SAC populations were sufficient . The most recent UNICEF guidelines have likewise stated that measuring UIC in SAC may conceal suboptimal iodine intake in subsets of vulnerable groups, including pregnant women . Studies from Austria , Denmark , China  and the United States  have also demonstrated marked iodine insufficiency among pregnant women despite using iodised salt and/or iodine supplements. Taken together, our study and the prior reports advocate that the health authorities in each country should consider measuring iodine intake in pregnant women independently from SAC to accurately evaluate iodine adequacy in this vulnerable group [7-11]. Educational programs should also be developed to increase the awareness of pregnant women, or those who are planning for conception, about the significance of iodine for them as well as for their offspring wellbeing [48, 49].
Iodine adequacy in reproductive age and pregnant women could be influenced by numerous factors . Herein, the risk of iodine deficiency in the non-pregnant population increased with multiparity, which agrees with studies from the United States , Denmark , Germany  and Italy . A possible construal for the associations between parity and iodine intake could be illustrated by the findings of Ratondi et al. who have proclaimed a cumulative, non-reversible goitrogenic effect for each pregnancy, which may require increasing iodine supply for preventing thyroid abnormalities . Additionally, earning below the Saudi minimal wage also increased the odds of inadequate iodine in our non-pregnant women. Likewise, a linkage between poverty and iodine inadequacy has been reported by several community studies, which could be due poor adherence of low-income populations to appropriate micronutrients and iodised salt intake [56, 57]. Numerous population-based studies have also demonstrated the negative impact of smoking on thyroid functions and iodine adequacy in reproductive age and pregnant women [50, 52, 53, 58, 59]. In agreement, our data showed that passive, but not active, smoking was an independent factor that significantly increased the risk of iodine inadequacy in both the non-pregnant and pregnant groups. Accordingly, the present study strengthens the numerous requests to employ the necessary policies for smoking cessation as well as to encourage pregnant women to avoid staying in rooms where others have smoked .
Our results also revealed 2-fold and 3-fold higher risks of iodine insufficiency for consuming non-iodised salt by the reproductive age and pregnant women, respectively. 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 USI target of 90% usage by the general population to avoid deficiency . More recently, the WHO has also recommended salt reduction to 5 gram/day for adults, including reproductive age and pregnant women, to reduce the likelihood of developing cardiovascular 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 recommendations post-fortification [62, 63]. Therefore, the reported inadequate use of iodised salt in KSA alongside the advised reduction of salt intake accentuate the importance of developing other vehicle(s) for delivering iodine, thus decreasing the incidence of iodine deficiency disorders [62, 63]. Furthermore, reproductive age (150 µg/day) and pregnant (250 µg/day) women could temporarily benefit from using daily iodine supplements till developing a solid and effective national salt/bread iodisation program [27, 62, 63].
The present study also showed a weak positive association between BMI and UIC, which correlates with previous reports from Bangladesh and Romania [64, 65]. 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 . On the contrary, several other studies either have reported negative association between BMI and UIC [9, 67] or have shown no correlation between body weight and iodine intake [8, 42]. 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 [68, 69].
The present study has several limitations. Although the number of participants is larger compared with several other reports on pregnant women [7-9], our participants were enrolled from a single site, and other cities from the same region were not included. Additionally, we did not measure the dietary habits and intake alongside the thyroid function parameters to investigate their correlations with iodine status. However, this is a phase 1 study and we will conduct further research to measure the interactions between nutritional habits, iodine intake and thyroid functions in pregnant women.