the role of the thyroid gland in pregnancy and the impact of thyroid disorders on the course of pregnancy and development of the offspring have drawn a considerable interest in the recent years , both in the medical and in the general society . about 2 and 4%
a growing body of evidence suggests that subclinical hypothyroidism may be associated with in vitro fertilization failure , subfertility , infertility , spontaneous abortion , placental abruption , gestational hypertension , preeclampsia , preterm delivery , postpartum thyroid dysfunction , depression ( including postpartum depression ) , conversion to overt hypothyroidism , and impaired cognitive and psychomotor child development .
american thyroid association in its recently published guidelines have stated against universal screening of pregnant women for hypothyroidism .
it seems that prevalence of hypothyroidism is more in asian countries compared to the west . in a recent study by dhanwal et al .
looking at these data the purpose of the study was to know whether routine screening would prove to be beneficial in our country .
the study was an out - patient department ( opd ) based prospective cohort , observational study in which 305 women were randomly selected and screened on opd basis by thyroid - stimulating hormone ( tsh ) levels ( cutoff level 0.10 - 2.50 miu / ml ) as per recent guidelines .
these women were followed till term and subsequent delivery to study the effect on maternal and perinatal outcome .
known cases of other medical disorders and women who did not give consent for tsh estimation were excluded from the study .
0.10mu / l , the reference values for tsh were 0.1 - 2.5miu / l , 0.2 - 3.0 miu / l and 0.3 - 3.0 miu / l in the first , second , and third trimesters of pregnancy respectively , considering the recent literature . the statistical difference between variables
in the study following are the observations made : the mean age of women was 24.46 years ( sd = 2.00 ) . the mean gestational age at time of screening 9.09 weeks .
( sd = 4.09 ) 38.68% of women were of gestational age less than 9 weeks and 61.31% were with gestational age 913 weeks .
cut off of 9 weeks was taken to identify those who presented early in first trimester , 55.08% women were nullipara , 31.14% were primipara , 11.47% were para 2 , 2.2% women were para 3 and more . it was seen that 4.9% women were already having symptoms of thyroid diseases ( main symptoms seen were weakness , lethargy , loss of appetite , weight gain ) , 4.2% had history of previous thyroid diseases ( which is either hypo or hyperthyroidism ) , 0.65% women had history of other autoimmune diseases ( apla syndrome ) 4.9% women had history of previous caesarean section , 1.6% women had family history of thyroid diseases , 0.3% had history of irradiation , 1.6% had history of medication ( thyroxine for hypothyroidism ) . on this screening
. however , the incidence of hypothyroidism in high risk population was 20.58% and in normal population was 6.7% which shows a significant association of thyroid disorders with high risk factors ( p < 0.001 ) . in the euthyroid women 7.2% had an adverse perinatal outcome , 92.7% had normal outcomes .
this shows statistically significant association abnormal tsh values with adverse pregnancy outcomes ( p < 0.001 ) . considering the route of delivery , 88.85% women had normal delivery , out of them 0.36% were hyperthyroid , 5.5% were hypothyroid rest were euthyroid .
in abnormal perinatal outcomes 6.2% women had lower segment caesarean section ( lscs ) out of them 73.68% were euthyroid and 26.31% were hypothyroid .
the main indications for lscs in these cases were fetal distress , maternal cephalopelvic disproportion ( cpd ) , contracted pelvis , and failed induction .
1.9% had preterm labour , out of them 50% were euthyroid , 50% were hypothyroid .
in all , there was only one preterm fresh still birth in a euthyroid woman .
out of 2.2% spontaneous abortions 28.5% were in euthyroid group while 71.4% were in hypothyroid group .
this study shows significant association between abnormal tsh values and adverse perinatal outcomes ( p < 0.001 ) .
this prospective screening of thyroid function in a cohort of unselected pregnant women shows that high - risk women ( with a personal or family history of thyroid disorders or a personal history of other autoimmune diseases ) have more significant ( p < 0.001 ) increased risk of hypothyroidism ( subclinical or overt ) during early pregnancy .
however , testing only the high - risk pregnant women , as the consensus guidelines recommend , would miss about one- of women with hypothyroidism .
therefore with the growing evidence for an association between maternal subclinical hypothyroidism and adverse pregnancy outcomes but lack of intervention trials showing beneficial effect of thyroxine ( t4 ) in preventing these adverse outcomes , the controversy between targeted high - risk case finding and universal screening continues .
the consensus guidelines recommend the use of t4 in pregnant women with subclinical hypothyroidism , justified on the basis of potential benefit to risk ratio .
our study shows that , without universal screening , a significant number of such pregnant women with thyroid dysfunction will not be picked up .
free thyroxine ( ft4 ) increases with suppression of tsh in response to placental human chorionic gonadotrophin during the first trimester , whereas ft4 tends to decrease in late gestation .
this is likely to be the cause for the high prevalence of suppressed tsh in this cohort .
furthermore increased serum thyroid - binding globulin and decreased albumin during pregnancy result in assay - dependent variations in ft4 levels .
these observations have led to the call for using trimester and assay - specific reference ranges for thyroid function tests in pregnancy .
if the trimester specific reference range is used , 9.8% pregnant women in this cohort will be considered to have hypothyroidism .
whereas there will be less of a controversy to use the trimester - specific reference range in titrating the dose of t4 in pregnant women on t4 replacement , further studies are needed to determine the threshold level of tsh at which initiation of t4 replacement should be considered .
clinical studies have confirmed that the increased requirement for t4 ( or exogenous lt4 ) occurs as early as 4 - 6 weeks of pregnancy .
such requirements gradually increase through 16 - 20 weeks of pregnancy , and thereafter plateau until time of delivery .
these data provide the basis for recommending adjustments to thyroid hormone in affected women once pregnant and for the timing of follow - up intervals for tsh in treated patients .
the levothyroxine ( lt4 ) adjustment , when necessary , should be made as soon as possible after pregnancy is confirmed to reduce the probability of hypothyroidism .
a prospective , randomized study has recently provided evidence in support of one dose adjustment strategy for women receiving lt4 who are newly pregnant . for women who are euthyroid while receiving once - daily dosing of lt4 ( regardless of amount ) , a recommendation to increase by two additional tablets weekly ( nine tablets per week instead of seven tablets per week ; 29% increase ) can effectively prevent maternal hypothyroidism during the first trimester and mimic gestational physiology .
this augmented dose should occur immediately after a missed menstrual cycle or suspected pregnancy occurs .
a separate option is to increase the dosage of daily lt4 by approximately 25 - 30% .
there is also an uncertainty regarding the most appropriate initial screening test for thyroid dysfunction in pregnancy .
the consensus guidelines recommend using tsh as the initial test , whereas others have stressed the importance of testing ft4 by highlighting the fact that ft4 ( and ft3 ) is responsible for thyroid hormone action and that maternal hypothyroxinemia ( normal tsh but low ft4 ) is associated with neuropsychological deficit in the offspring . in our study ,
the cause of maternal hypothyroxemia is not fully understood , but iodine deficiency is thought to be a major factor although urinary iodine was not analyzed in the present cohort , a previous study in this same population has shown that 7 and 40% pregnant women have urinary iodine excretion of less than 50 g / l ( suggestive of dietary iodine deficiency ) and 50 - 100
nearly one - quarter of hypothyroid women on t4 replacement in this study had raised tsh at their first antenatal visit .
given the fact that the fetus relies entirely on maternal thyroid hormones for its development until about 13 week of gestation , it is critical to ensure adequate t4 replacement in pregnant women during the first trimester .
hypothyroid pregnant women on t4 require an increased dose from as early as the fifth week of gestation to maintain optimum t4 replacement .
some recommend a 30% increase in the t4 dose as soon as the pregnancy is confirmed , with further dose adjustments based on tsh measurements .
in addition , through education of all hypothyroid women in the reproductive age , every attempt should be made to ensure an adequate t4 replacement before a planned pregnancy .
so screening of thyroid disorders should be done in early pregnancy . it will help to diagnose the cases at the earliest and to carry out timely intervention to prevent adverse perinatal outcomes .
but still there is a controversy regarding universal thyroid function screening or high - risk screening in early pregnancy .
but if we screen only high risk population we would miss 4.6% cases which could have been diagnosed and treated earlier .
so this study emphasizes high risk screening in early pregnancy but also supports that universal screening should be a part of our screening protocols so that all thyroid disorders are screened and treated at the earliest .
so in our country we must follow indian thyroid society guidelines which clearly recommend that  all pregnant women should be screened at 1 antenatal visit by measuring tsh levels  , and highlight that  ideally screening should be carried out during prepregnancy evaluation or as soon as pregnancy is confirmed . 
 objective : to determine the importance of screening for thyriod disorders in the first trimester of pregnancy.materials and methods : the study was conducted on 305 patients which were were randomly selected and screened on opd basis by tsh levels ( cut off level 0.10 - 2.50 miu / ml).results : in the 305 women screened mean age was 24.46 years , mean gestational age was 9.09 weeks , 89.83% were euthyroid , 9.8%were hypothyroid , 0.32% were hyperthyroid . 
 incidence of hypothyroidism in high risk population was 20.58% and in normal population was 6.7% . 
 there was significant association of thyroid disorders with high risk factors ( p < 0.001 ) . 
 in hypothyroid women 46% had adverse perinatal outcomes and 53.33% had normal outcomes . 
 this shows statistically significant association abnormal tsh values with adverse pregnancy outcomes ( p < 0.001 ) . in abnormal perinatal outcomes 6.2% women had caesarean section out of them 73.68% were euthyroid , 26.31% were hypothyroid 1.9% had preterm labour , out of them 50% were euthyroid , 50% were hypothyroid . out of 2.2% spontaneous abortions 
 28.5% were in euthyroid group while 71.4% were in hypothyroid group . 
 there was 1 term stillbirth in hypothyroid group . 
 this study showed significant association between abnormal thyroid stimulating hormone ( tsh ) values and adverse perinatal outcomes ( p < 0.001).conclusion : there is significant correlation between risk factors and hypothyroidism . 
 so high risk screening is mandatory in early pregnancy . 
 but if we screen only high risk population we would miss 4.6% cases which could have been diagnosed and treated earlier . 
 therefore it is important to screen all pregnant women in the first trimester , it should be made mandatory . 
I
M
R
D
C