A Study to Assess the Risk Factors of Thyroid Functions among Bangladeshi Women during 1st Trimester of Pregnancy

Background: In recent years many researches has centered on the inuence of thyroid disease on pregnancy and the consequence of offspring. Aim: The present study was conducted to evaluate the relationship of multiple risk factors and thyroid functions among Bangladeshi young women during 1st half of the pregnancy. Material and methods: This cross-sectional study was done in in the Department of Obstetrics & Gynecology of Dhaka Medical College Hospital, Dhaka on 200 pregnant women in their 1st half of pregnancy attending antenatal clinic, DMCH from December 2018 to December 2019. Where inclusion criteria were healthy singleton pregnant women up to 20 weeks of gestation. Results: According to this study, 10.5% subclinical hypothyroidism group and 36.8% from overt hypothyroidism patients had family history of thyroid dysfunction. 6.5% had stage-1 hypertension and 11% patients had stage-2 hypertension. Also, abnormal blood pressure level is highly correlated with thyroid dysfunction status. The rate of iron disfunction strongly correlated with thyroid dysfunction. 6% patients had mid-level of iron deciency and 13.5% had iron deciency anemia. Also, 62.5% had mild hemoglobin level and 37.5% had moderate- severe mild hemoglobin level. Conclusion: The results indicate that, iron deciency, hypertension can be seen in hypothyroidism during the 1st half of pregnancy. Hence, routine thyroid monitoring, checkup and appropriate management is necessary for hyperthyroidism in the 1st half of pregnancy to avoid more adverse outcome. This cross-sectional study has been performed over 200 pregnant women in their 1 st half of pregnancy attending antenatal clinic. In this study, the risk factors those were comparatively higher in correlation with thyroid disfunction, were hemoglobin level, iron deciency, genetic inheritance, blood pressure, TSH and FT4 level.


Introduction
Among women of childbearing age, thyroid disorder is especially severe. Estimates indicate a degree of hypothyroidism among 2.5 percent of all pregnant people. The second most prevalent endocrine disorder in pregnancy is thyroid dysfunction. 1 Maternal thyroid function changing activity during pregnancy result in thyroid disease and poor tolerance to these shifts. During pregnancy, maternal thyroid function changes and inadequate adaptation to these changes causes thyroid dysfunction.
Such changes are the result of multiple causes such as an increase in thyroglobulin because of elevated estrogen and human Chorionic gonadotrophin, decreased iodine losses from renal disorders attributable to the growth of glomerular ltration, modi cations in peripheral metabolism of maternal thyroid hormone and alterations in iodine transfer to placenta. During pregnancy, the development of thyroid Page 3/9 hormone and iodine rises by 50%. In people with low thyroid reserve or iodine de ciency, pregnancy is a stress check for thyroid, which contributes to hypothyroidism. 2 In pregnancy thyroid dysfunction was linked with adverse obstetric and fetal outcome. Most of these complications are miscarriage, anaemia, hypertension, preeclampsia, placental abruption, preterm labor, congestive heart failure, postpartum hemorrhage and the fetal complications are prematurity, birth asphyxia, low birth weight, low Apgar score, still birth, perinatal death, increased neonatal respiratory distress and decreased childhood cognitive function. 3 Therefore, thyroid dysfunction (sub-clinical or overt) during early pregnancy is of utmost importance for clinician to detect thyroid dysfunction. 4 A safe and accurate examination of thyroid function during the pregnancy is thus important, since maternal thyroid de ciency can in uence maternal safety, fetal well-being and obstetric results. 5 The only way of evaluating the pathophysiologic features of thyroid dissolution during pregnancy, which can also detect minor thyroid abnormalities, is the detection of the thyroid function by using serum TSH during pregnancy. 4 Therefore, early pregnancy screening for people at high risk is mandatory. But we would lose 4% of patients that we could have diagnosed and treated earlier if we only scan the community with a high risk. It is thus important for all pregnant women to be checked for compulsory in the rst trimester of pregnancy. 6 The objective of the study was to assess the relationship of multiple risk factors and thyroid functions among Bangladeshi young women during 1 st half of the pregnancy. With aseptic precaution 5 ml. of venous blood drawn from each patient and taken into a sterile test tube which kept in standing position up to full formation of clot then serum was separated and taken into two eppendorf's. After that send to the laboratory for measurement of serum TSH, FT 3 and FT 4. Serum sample will be immediately assayed for the levels of serum TSH and serum samples were stored at 4°C for levels of FT 3 and FT 4 . However, the serum FT 3 and FT 4 were estimated only in those women who exhibit abnormal serum TSH levels. Estimation was carried out by ADIVA centaur CP and Radioimmunoassay.

Materials And Methods
Written consent was taken from those who agreed to participate in the study. Date were collected in a structured questionnaire by the history taking, clinical examination and biochemical investigations.
Data analysis: Data were processed and analyzed using SPSS (statistical Package for social sciences), window version 21.0. The test statistics was used to analyze the data are chi-square(x 2 ) test and unpaired student's t-test with its 95% con dence interval (CI). For all analytical tests, the level of signi cance will be set at 0.05 and p value of < 0.05 will be considered statistically signi cant. Ethical clearance was obtained from appropriate authority. Privacy and con dentiality were strictly maintained.

Results
The demographic characteristics of 200 thyroid pregnant women in the rst half of pregnancy where, most of the patients belong to 20-25 years age group. From euthyroid group 87.8% patients completed their graduation where as in subclinical and overt hypothyroidism group it was 4.9% and 7.3%. From subclinical and overt hypothyroidism group 6.3% pregnant women were underweight and 1.4%, 15  In table-4 shows comparison of thyroid function among different groups according to iron status where serum TSH concentrations were higher and FT4 concentrations were lower in IDA group than Mid iron de ciency and normal group. The following table is given below in detail:

Discussion
This cross-sectional study has been performed over 200 pregnant women in their 1 st half of pregnancy attending antenatal clinic. In this study, the risk factors those were comparatively higher in correlation with thyroid disfunction, were hemoglobin level, iron de ciency, genetic inheritance, blood pressure, TSH and FT4 level.
Moreover, according thyroid status and their 1st half of the pregnancy we divided patients into three group. We found that most of the patients belong to 20-25 years age group, where 8.4% belong subclinical hypothyroidism group, 14.3% were hypothyroidism and 77.35% patients were euthyroid group.
In a study in Poland, 10.4% of the pregnant women screened for thyroid dysfunction in their 1st trimester exhibited (hypothyroidism), which is quite close to this study ndings. 7 In a similar study conducted in Bangladesh where, clinical and subclinical hypothyroidism together comprised 8% of the pregnant women and clinical and subclinical hyperthyroidism together formed 7.5% thus constituting a total 15.5% with abnormal thyroid function which compares well with the ndings of the present study. 4 According to other report, in contrast to hyperthyroidism, hypothyroidism is quite common in pregnancy, which correlated with this study where subclinical hypothyroidism was 13% in comparison to subclinical hyperthyroidism(3%). 8 However, in another study of screening for subclinical hypothyroidism in pregnant women demonstrated a much lower proportion of hypothyroid status (1 in 40 antenatal mothers screened). 9 According to our study, we didn't nd any association between age and thyroid function alteration. Which is supported by one study. 4 In this study neither gravidity of women nor their gestational age was found to be associated with their thyroid function status. While an Indian study reported no variations in serum TSH and serum FT3 between trimesters, but there is a signi cant variation in FT4 between trimesters with values decreasing with advancing gestational age. 10 But we found that genetic inheritance is signi cantly associated with thyroid dysfunction. Where 10.5% subclinical hypothyroidism group and 36.8% from overt hypothyroidism patients had family history of thyroid dysfunction. In one study said that, autoimmune thyroid disease commonly runs in families, and the search for genes which increase susceptibility has identi ed several good candidates, particularly those involved in immune regulation and thyroid function. 11 From our study, we also found that the rate of iron disfunction strongly correlated with thyroid dysfunction. 6% patients had mid-level of iron de ciency and 13.5% had iron de ciency anemia. Also, 62.5% had mild hemoglobin level and 37.5% had moderate-severe mild hemoglobin level. Lower hemoglobin level is signi cantly associated with thyroid dysfunction too. In one report said that, Hemoglobin levels of less than 11 g/dL at any time during pregnancy are considered abnormal. Once anemia is recognized, the possibility of iron de ciency should be considered. 12 Up to 52% of pregnant women in the developing world are affected. 13 Lowered iron stores in their newborn baby will increase the risk of subsequent iron de ciency anemia. Prematurity and early weaning off breastfeeding increases the risk further, because of reduced iron stores. 14 Hypertension is the world's leading preventable risk for early death and disability, affecting 26.4% of the world's adult population. [15][16] Apart from the majority of patients with main (essential) elevated blood pressure, the secondary hypertension subgroup of ~10 % is affected. Among the underlying diseases several are of endocrine origin and thyroidal impairments represent an even smaller percentage of the secondary hypertension cases; their incidence and form of presentation varies with age and studied population. 17 Thyroid dysfunctions, both hypo-and hyperthyroidism may increase the risk of hypertension. [18][19] In our study we found similar type of result where 6.5% had stage-1 hypertension and 11% patients had stage-2 hypertension. Also, abnormal blood pressure level is highly correlated with thyroid dysfunction status.
Another article mentioned that, Hypothyroid patients have other atherosclerotic cardiovascular disease risk factors and an apparent increase in risk of stroke as well. [20][21] The blood pressure changes, alterations in lipid metabolism, decreased cardiac contractility, and increased SVR that accompany hypothyroidism are caused by decreased thyroid hormone and action on multiple organs such as the heart, liver, and peripheral vasculature and are potentially reversible with thyroid hormone replacement. 22 In present study serum FT4 concentrations were lower and TSH concentrations were higher in subjects with iron de ciency, which quite similar to other studies. [23][24] Also, in our study changes of FT4 and TSH level were highly correlated with thyroid dysfunction.

Conclusion
From the ndings of the study and discussion thereof it can be concluded that almost one and half (1.53) in every ten overweight women may have thyroid disorder (overt hypothyroidism) in the rst half of pregnancy. Besides, there can be a link between family history and thyroidism because around three and half in every ten-patient had family history of thyroid dysfunction. None of the rest demographic and obstetric characteristics plays any role in the development of abnormality in thyroid function. Euthyroid hypothyroidism is far more common than the subclinical and overt hyperthyroidism. The proportion of iron de ciency, hemoglobin and hypertension is strongly correlated with thyroid dysfunction too. So, if feasible routine screening at least serum TSH level can be done in all pregnant women attending antenatal visit. Routine thyroid monitoring, checkup and appropriate management is necessary for hyperthyroidism and especially in the very 1 st half of pregnancy to avoid more adverse outcome Declarations Ethical clearance was obtained from appropriate authority. Privacy and con dentiality were strictly maintained.