Iodine deficiency during pregnancy: a national cross-sectional survey in Latvia.
OBJECTIVE
Low iodine intake during pregnancy may cause thyroid dysfunction, which results in inadequate fetal brain development. In the absence of a universal salt iodization programme, we conducted a nationwide survey of iodine deficiency in pregnant women in Latvia.


METHODS
A countrywide twenty-cluster survey, with at least twenty women per cluster. Participants completed a questionnaire on dietary habits concerning iodine intake (n 739). Thyroid function (thyroid-stimulating hormone, free thyroxine and thyroperoxidase antibodies) was measured (n 550). Urinary iodine was measured using the ammonium persulfate method (n 696).


METHODS
The survey was performed in all regions of Latvia during the spring and autumn seasons in 2013.


METHODS
Pregnant women (n 829).


RESULTS
The median creatinine (Cr)-standardized urinary iodine concentration (UIC) was 80·8 (interquartile range (IQR) 46·1-130·6) µg/g Cr or 69·4 (IQR 53·9-92·6) µg/l during pregnancy, and 81% of pregnant women had UIC levels below the WHO recommended range of 150-250 µg/g Cr. The UIC was lowest during the first trimester of pregnancy, 56·0 (IQR 36·4-100·6) µg/g Cr, reaching higher concentrations of 87·5 (IQR 46·4-141·7) µg/g Cr and 86·9 (IQR 53·8-140·6) µg/g Cr in the second and third trimesters, respectively. Women taking supplements containing ≥150 µg iodine (6·8% of respondents) had non-significantly higher UIC than did women without supplementation (96·2 v. 80·3 µg/g Cr, respectively, P=NS). Thyroperoxidase antibody concentration did not correlate significantly with UIC: Spearman's ρ=-0·012, P=0·78.


CONCLUSIONS
The median UIC indicates iodine deficiency in pregnant women in Latvia. Iodine supplementation (150 µg daily) and regular UIC monitoring should be suggested to overcome iodine deficiency and to reach the recommended levels without inducing autoimmune processes.
1Riga Stradins University,Riga,Latvia.
Ilze
I
Konrade
1Riga Stradins University,Riga,Latvia.
Ieva
I
Kalere
1Riga Stradins University,Riga,Latvia.
Ieva
I
Strele
1Riga Stradins University,Riga,Latvia.
Marina
M
Makrecka-Kuka
1Riga Stradins University,Riga,Latvia.
Anna
A
Jekabsone
1Riga Stradins University,Riga,Latvia.
Elina
E
Tetere
1Riga Stradins University,Riga,Latvia.
Vija
V
Veisa
4E. Gulbis Laboratory,Riga,Latvia.
Didzis
D
Gavars
1Riga Stradins University,Riga,Latvia.
Dace
D
Rezeberga
5University of Latvia,Riga,Latvia.
Valdis
V
Pīrāgs
1Riga Stradins University,Riga,Latvia.
Aivars
A
Lejnieks
1Riga Stradins University,Riga,Latvia.
Maija
M
Dambrova
D000328:Adult; D003430:Cross-Sectional Studies; D003677:Deficiency Diseases / Q000453:epidemiology* / Q000652:urine; D004032:Diet; D004034:Diet Surveys; D019587:Dietary Supplements; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D007455:Iodine / Q000172:deficiency* / Q000652:urine; D007844:Latvia / Q000453:epidemiology; D009752:Nutritional Status; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology* / Q000652:urine; D011264:Pregnancy Trimesters; D017673:Sodium Chloride, Dietary; D013961:Thyroid Gland / Q000276:immunology / Q000502:physiology
D017673:Sodium Chloride, Dietary; C034024:iodized salt; D007455:Iodine
Iodine deficiency; Iodine supplementation; Pregnancy