Low Iodine Intake From Food May Increase Perinatal Depression Risk

Perinatal emotional distress and depression may be related to low iodine intake from food, according to results of a study published in Journal of Affective Disorders.

Researchers from the Norwegian Institute of Public Health sourced data for this analysis from the Norwegian Mother, Father, and Child Cohort Study, which was a large prospective population-based pregnancy study. Pregnant women (N=77,927) recruited between 2002 and 2008 were evaluated for food intake and the presence of perinatal emotional distress and depression using the Hopkins Symptoms Checklist-5 (HSCL-5) and Edinburgh Postnatal Depression Scale (EDPS) instruments.

Most of the women in the study population were aged 25 to 34 years at delivery (72%), had a prepregnancy body mass index (BMI) of 18.5 to 24.9 kg/m² (66%), did not smoke during pregnancy (79%), and did not have a chronic illness (90%). The median iodine intake from food was 121 µg/day.

Over a third of women (37%) endorsed using an iodine supplement between gestational weeks 0 and 22. Using an iodine supplement was associated with the presence of a chronic illness (odds ratio [OR], 1.18; 95% CI, 1.12-1.23), more than 16 years of education (OR, 1.17; 95% CI, 1.12-1.22) and 13 to 16 years of education (OR, 1.16) compared with 12 years or fewer of education, age of at least 35 years compared with 25 to 34 years (OR, 1.16; 95% CI, 1.12-1.21), and prepregnancy BMI below 18.5 kg/m² compared with 18.5 to 24.9 kg/m² (OR, 1.14; 95% CI, 1.04-1.24).

Risk for HSCL-5 score of at least 2 at gestational week 17 (6.3%) and 6 months postpartum (5.5%) scaled with the amount of iodine obtained from food (both P <.001) in which women who consumed 25 µg/day had an adjusted OR of 1.57 (95% CI, 1.30-1.90) at gestational week 17 and 1.65 at postpartum month 6; women who consumed 300 µg/day had an adjusted OR of 0.89 (95% CI, 0.76-1.03) at gestational week 17 and 0.96 at postpartum month 6 compared with women who consumed 160 µg/day (95% CI, 0.91-1.01).

Researchers observed a similar trend in the relationship between iodine consumption from food and EDPS score of at least 1.3 (10.1%) at 6 months postpartum (P <.001).

Among the women who had high HSCL-5 scores at gestational week 17 (n=1980) and a group of matched controls (n=30,087), risk for depression was associated with any iodine supplement use (OR, 1.17; 95% CI, 1.07-1.28; P =.001) and supplementation during gestational weeks 0 to 12 (OR, 1.17; 95% CI, 1.04-1.31; P =.010), before pregnancy (OR, 1.14; 95% CI, 1.01-1.28; P =.040), and after gestational week 12 (OR, 1.14; 95% CI, 1.00-1.30; P =.046) compared with women who did not supplement with iodine.

Limitations of the study include the fact that iodine intake was based on the food frequency questionnaire which may be vulnerable to misreporting.

Study authors concluded, “This study is the first to indicate that insufficient maternal habitual iodine intake is associated with symptoms of perinatal emotional distress and depression. However, use of iodine supplements provided no benefit but was associated with higher prevalence of emotional distress and depression. Thus, the results must be interpreted with care. The study needs to be replicated by other well-powered studies in mild-to-moderately iodine deficient populations.”

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.