Hypertension and Salt-Restrictive Diet Promotes Low Urinary Iodine Concentration in High-Risk Pregnant Women: Results from a Cross-Sectional Study Conducted After Salt Iodination Reduction in Brazil

During pregnancy, the demand for daily iodine increases by 50–70% which occurs to reach around 250 μg/day. Limited information is available on the association of high-risk pregnancy (HRP) with urinary iodine concentration (UIC) and variables such as socioeconomic factors. To analyze iodine nutritional status and socioeconomic, demographic and anthropometric characteristics among women with HRP screened at the main referral public health center at Bahia, Brazil, a cross-sectional study was conducted in 241 women with HRP (15–46 years old) in Salvador, Bahia, Brazil. The median UIC (MUIC) was 119 μg/L (25–75th, 58.7–200.4 μg/L), indicating mild iodine deficiency. Low UIC (< 150 μg/L) was detected in 61.8% ( n = 149) – 18.3% between 100 and 150 μg/L, 24.5% between 50 and 100 μg/L, and 19.1% with UIC < 50 μg/L. Overall, 53% ( n = 128) of our population adhered to a low-salt diet, and 32.5% ( n = 77) had hypertension. Among the 73% of hypertensive women adhering to a salt-restricted diet, there was a 112% increased risk of iodine deficiency observed (OR = 2.127; 95% confidence interval [1.178–3.829]; p = 0.011). Adhering to a salt-restricted diet was associated with iodine deficiency (OR = 1.82; 95% confidence interval [1.073–3.088], p = 0,026). Hypertension and salt restriction diet significantly increased susceptibility for iodine deficiency in HRP. Therefore, low-salt diet when prescribed to pregnant women (PW) might be carefully followed by iodine nutritional status assessment or universal preconception iodine supplementation.