title: Effects of maternal iodine supplementation during pregnancy. Neurological damage to the fetus resulting from severe iodine deficiency during pregnancy. A randomized trial for the treatment of mild iodine deficiency during pregnancy: maternal and neonatal effects. Prevention of iodine deficiency disorders by oral administration of lipiodol during pregnancy. The effects of iodoprophylaxis on thyroid size during pregnancy.
abstract: Reduced maternal thyroid hormone concentrations during pregnancy can adversely affect fetal neurological development . In the context of national iodine supplementation programmes , concern has been expressed over the theoretical possibility that iodine supplementation during pregnancy might adversely affect fetal development as a result of maternal thyroid inhibition from the Wolff-Chaikoff effect . In a double blind controlled trial in five villages in Papua New Guinea , several measures of motor and cognitive function showed no significant differences at either age 11 or 15 years between those children whose mothers had received supplementary iodine during pregnancy and the control children whose mothers had received the placebo Abstract Endemic cretinism is characterised by multiple neurological defects including deaf-mutism , diplegia , squint , and mental deficiency . The condition is widely prevalent in the Highl and s of New Guinea in association with severe iodine deficiency . Previous studies have shown that iodised oil provides a very satisfactory correction of severe iodine deficiency in New Guinea . A controlled trial on the use of intramuscular iodised oil in the prevention of endemic cretinism was carried out in the Western Highl and s of New Guinea and involved a population of approximately 8000 . Subsequent follow-up over four years revealed 26 endemic cretins out of a total of 534 children born to mothers who had not received iodised oil ; the mothers of 5 of these cretins were pregnant at the start of the trial . In comparison , 7 cases of endemic cretinism occurred among 498 children born to mothers who had been treated with iodised oil ;  in 6 of these 7 cases , the mother was pregnant when the trial commenced . It is concluded that intramuscular iodised oil is effective in the prevention of endemic cretinism and that , for it to be effective , it should be given prior to conception . This suggests that severe iodine deficiency in the mother produces neurological damage during fetal development One hundred and eighty euthyroid pregnant women were selected at the end of the first trimester of gestation on the basis of biochemical criteria of excessive thyroid stimulation , defined as supranormal serum thyroglobulin ( TG > 20 micrograms/L ) associated with a low normal free T4 index ( < 1.23 ) and /or an increased T3/T4 ratio ( > 25 x 10(-3 ) ) . Women were r and omized in a double blind protocol into three groups and treated until term with a placebo , 100 micrograms potassium iodide (KI)/day , or 100 micrograms iodide plus 100 micrograms L-T4/day . Parameters of thyroid function , urinary iodine excretion , and thyroid volume were monitored sequentially . Neonatal thyroid parameters , including thyroid volume by echography , were also assessed in the newborns from mothers of the three groups . In women receiving a placebo , the indices of excessive thyroid stimulation worsened as gestation progressed , with low free T4 levels , markedly increased serum TG and T3/T4 ratio . Serum TSH doubled , on the average , and was supranormal in 20 % of the cases at term . Urinary iodine excretion levels were low , around 30 micrograms/L at term . The thyroid volume increased , on the average , by 30 % , and 16 % of the women developed a goiter , confirming the goitrogenic stimulus associated with pregnancy . Moreover , the newborns of these mothers had significantly larger thyroid volumes at birth as well as elevated serum TG levels . In both groups of women receiving an active treatment , the alterations in thyroid function associated with pregnancy were markedly improved . The increase in serum TSH was almost suppressed , serum TG decreased significantly , and changes in thyroid volume were minimized ( group receiving KI ) or almost suppressed ( group receiving KI combined with L-T4 ) . Moreover , in the newborns of the mothers in the two groups receiving an active treatment , serum TG was significantly lower , and thyroid volume at birth was normal . The effects of therapy were clearly more rapid and more marked in the group receiving a combination of T4 and KI than in the women receiving KI alone . The differences could be partly attributed to the slightly higher amount of iodine received by women in the combined treatment . However , the main benefits of the combined treatment were almost certainly attributable to the hormonal effects of the addition of L-T4 . Furthermore , the study demonstrated that the administration of T4 did not hamper the beneficial effect of iodine supplementation . In conclusion , the present work emphasizes the potential risk of goitrogenic stimulation in both mother and newborn in the presence of mild iodine deficiency . ( ABSTRACT TRUNCATED AT 400 WORDS The prevalence of iodine deficiency disorders and the thyroid status of the population were studied in an endemic goitre area in Algeria . After oral administration of lipiodol ( 0.5 ml ) , three treated groups of mother-newborn couples were compared to an untreated group : group A , mothers treated 1 - 3 months before conception ; group B , mothers treated during the first month of pregnancy ; group C , mothers treated during the third month of pregnancy . Untreated mothers were used as a control ( group D ) . After lipiodol treatment , all newborn babies and mothers were clinical ly euthyroid . All tested newborn babies were full term and no goitre was observed in the four groups . In the mothers , goitre prevalence and thyrotrophin levels decreased significantly , whereas maternal milk and urinary iodine and serum-free thyroxine levels were significantly higher after treatment . The rate of prematurity , stillbirths and abortions in the treated groups was reduced when compared to the untreated group , whereas placental and birth weights were significantly higher . In group D two cases of neonatal hypothyroidism were detected . Their re-evaluation confirmed that hypothyroidism was transient . Groups A , B and C were statistically different from group D with regard to neonatal thyrotrophin and thyroxine . Positive correlations were found between neonatal thyroxine and birth weights and placental weights on the one h and , and maternal urinary iodine and free thyroxine on the other . Consequently , these data indicate that oral administration of lipiodol before or during the first trimester of pregnancy normalizes thyroid function in newborn babies and mothers , increases placental and birth weight and reduces the frequency of iodine deficiency disorders . ( ABSTRACT TRUNCATED AT 250 WORDS Thyroid gl and size was ultrasonographically determined in 35 pregnant women who live in an area with moderate iodine deficiency .  Iodide salt was administered to group A ( n = 17 ) , whereas group B ( n = 18 ) was used as a control . Each group was tested for thyroid-stimulating hormone serum levels , iodine excretion , and thyroid volume . In both groups thyroid-stimulating hormone levels were similar and did not change throughout pregnancy . The iodine excretion at the third trimester in the treated group was significantly ( p less than 0.01 ) higher than that of group B ( 100.0 + /- 39.0 versus 50.0 + /- 37.0 micrograms iodine per 24 hours , respectively ) . Initially , thyroid volume did not differ between the two groups . At the end of pregnancy , no difference was found in thyroid size in group A , whereas in the untreated women it increased significantly ( p less than 0.0001 ) with a mean increase of 1.6 + /- 0.6 ml ( 16.2 % + /- 6.0 % ) . These results show that the increased thyroid size in the control group was mainly a result of relative iodine deficiency and that iodoprophylaxis should be warranted even in areas with moderate iodine deficiency to prevent the increase in thyroid size and , probably , to avoid the risk of maternal and fetal hypothyroidism
target: REVIEW ER 'S CONCLUSIONS Iodine supplementation in a population with high levels of endemic cretinism results in an important reduction in the incidence of the condition with no apparent adverse effects
background: BACKGROUND Iodine deficiency is the leading preventable cause of intellectual impairment in the world .
  Although iodine supplementation is generally considered to be safe , there is a possibility of high doses of iodine suppressing maternal thyroid function .
  OBJECTIVES The objective of this review was to assess the effects of iodine supplementation before or during pregnancy in areas of iodine deficiency .