the incidence of preeclampsia (21). In another
clinical trial by Negro et al in 2007, the efficacy
of selenium (Se) supplementation on reducing
pregnancy complications and postpartum thyroid
dysfunction was compared for the first time with
placebo. In this study, not only no significant reductions
were observed in preterm labor and preeclampsia
rates as primary outcomes, but also the
incidence of miscarriage did not decreased significantly
using Se (22). According to two mentioned
studies of Negro et al, application of LT or Se would
not lead to significant reduction of pre-eclampsia
in TPOAb-positive pregnant women. It can be also
concluded that application of LT might be able to
reduce the rate of preterm labor in TPOAb-positive
pregnancies unlike the application of Se.
According to the study of Negro et al in 2007, postpartum
thyroid dysfunction can be decreased significantly
(RR 0.59; 95% CI 0.38 to 0.90)-(RD -0.20;
95% CI -0.35 to -0.05) by using Se supplementation
for TPOAb-positive pregnant women (22).
In both of the studies of Negro et al by using LT
or Se, significant reduction was only observed in
miscarriage rate and no significant reduction was
revealed in gestational hypertension or placental
abruption as the secondary outcomes.
The efficacy of pre-pregnancy LT therapy in
hypothyroidism cases to reduce the gestational
complications during pregnancy was also
evaluated in one prospective study (23). In this
study, preconception suppressive LT therapy
in hypothyroidism cases was considered to be
effective in thyroid function during pregnancy,
which was similar to the results obtained by
Negro et al in 2006 (23). Initiating the application
of increased doses of LT before the 11 weeks
of gestation would significantly decrease the
possibility of maternal hypothyroidism and
further complications (24).
In conclusion, although iodine deficiency and thyroid
disorders are among the public health dilemmas,
there are not adequate country-based epidemiological
studies about the prevalence of thyroid
dysfunction. Although LT and Se are two common
treatments in women with hypothyroidism anticipating
pregnancy, further trials are needed to
establish the efficacy of these treatment effects on
improving the pregnancy outcomes.