Sharma V.1, Shukla N.2
1Dr. Varuni
Sharma, Department of Obstetrics & Gynaecology, 2Dr. Navin
Shukla, Department of Otorhinolaryngololgy & Head & Neck Surgery, both
authors are affiliated with Subharti Medical College, Dehradun, Uttarakhand,
India.
Correspondence Author: Dr. Varuni Sharma,
Department of Obstetrics & Gynaecology, Subharti Medical College, Dehradun,
Uttarakhand, India. E-mail: drvarunishukla@gmail.com
Background:
Thyroid disorders are among the
most common endocrine disorders in pregnant females. Hypothyroidism is more
common during pregnancy than hyperthyroidism. The overall prevalence of subclinical
hypothyroidism in general population has been reported to be 4% -8.5% while overt
hypothyroidism is 0.2 – 0.3% (2). Objective: To evaluate the prevalence of hypothyroidism in pregnancy and to
determine association of feto-maternal outcome with hypothyroidism. Material
and Methods: A Prospective study conducted over 120 patients who came to routine
antenatal care and/or admitted in labour room of Subharti Hospital, Dehradun over a
period of 01 year. Women with singleton pregnancy irrespective of the period of
gestation were randomly selected for the study. Patients thus selected were
divided into two groups: Control Group:
This comprised of pregnant females in whom serum TSH and FT4 levels were found
to be within normal range on estimation. Study
Group: This group included pregnant females who were diagnosed as cases of
subclinical hypothyroidism on the basis of raised TSH and normal TF4 levels and
overt hypothyroidism on basis of raised TSH and decreased TF4. Results:
The prevalence of hypothyroidism came out to be 24.29%. Higher
rate of still births, hyperbilirubinemia and admission to neonatal ICU (foetal
distress, meconium stained liquor) in the hypothyroid group were observed. Conclusion:
Hypothyroidismcontinues to be an important medical condition in pregnancy with
significant feto-maternal morbidity. Due to the adverse effect of maternal
thyroid disorder on maternal and fetal outcome, timely diagnosis and initiation
of treatment of hypothyroid disorders is essential.
Keywords:
Thyroid
Dysfunction, Thyroid disorder, Pregnancy, Hypothyroidism, Outcome
Thyroid disorders are among
the most common endocrine disorders in pregnant females. Hypothyroidism is more
common during pregnancy than hyperthyroidism [1]. Pregnancy is associated with
significant but reversible changes in maternal thyroid physiology that can lead
to confusion on the diagnosis or evaluation of thyroid abnormalities.
Subclinical
hypothyroidism is defined as increase in serum TSH usually (4-10Mu/L)
associated with normal concentration of serum thyroxine and
triiodothyronine.Overt hypothyroidism is diagnosed when high serum thyrotropin
level is accompanied by abnormal low thyroxine level.
The overall prevalence of
subclinical hypothyroidism in general population has been reported to be 4%
-8.5% while overt hypothyroidism is 0.2 – 0.3 %[2]. Women with hypothyroidism
can still conceive, although infertility rates are higher and failure of in
vitro fertilization is more likely. Pregnant women with hypothyroidism have a
greater risk of early and late obstetric complications such as miscarriage,
anaemia, gestational hypertension, placental abruption, premature delivery, post-partumhaemorrhage
and admission of their baby to neonatal intensive care (particularly for RDS)[3].
The detrimental effects of
maternal thyroid deficiency on foetal development are thought to depend on the
severity and early onset of a reduced availability of maternal thyroid hormones.
Recent studies indicate that undiagnosed (and hence untreated) hypothyroidism
during the first half of pregnancy is associated with a risk of poorer neurodevelopment
outcome in the progeny [4].
Considering the
wide-spread clinical implications of gestational sub & - clinical
hypothyroidism and its sequelae, this study was planned to know the prevalence
of hypothyroidism in pregnant women attending the antenatal care at Department of Obstetrics & Gynaecology of Subharti
Hospital, Dehradun.
Thestudy was conducted
over 120 patientswho came to routine antenatal care or were admitted in labour
room of Subharti Hospital, Dehradun over a period of one year (from 1st May 2015
to 30th April 2016).
Study design: Prospective study
Inclusion
criteria
Among the pregnant women
who attended antenatal clinic or were admitted in labour room, women with
singleton pregnancy irrespective of the period of gestation were randomly
selected for the study. Patients were divided into two groups:
1.
Control Group: This comprised of
pregnant females in whom serum TSH and FT4 levels were found to be within
normal range on estimation.
2.
Study Group: This group included
pregnant females who were diagnosed as cases of subclinical hypothyroidism on
the basis of raised TSH and normal TF4 levels and overt hypothyroidism on basis
of raised TSH and decreased TF4.
10 cases were diagnosed as
hypothyroid but had pregnancy loss were dropped out from the study as they
could not be followed for maternal and fetal outcome
Exclusion criteria
1. Already diagnosed hypothyroidism.
2. Multiple pregnancy
3. Women on treatment for
thyroid dysfunction
4. Any medical co morbidity
Study Protocol- All patients were registered at their
first antenatal visit. At the time of registration detailed history was taken and
general examination was done.
Blood was taken for
estimation of S.TSH and FT4. Hb, ABO, Rh, RBS, HIV, HBsAg and urine R/M were
done as a part of routine test.
Normal values taken in the
present:
TSH:0.465-5.68 mIU/ml
FT4:10.0-28.2 pmol/L
After
registering the patients, theywere followed up with routine antenatal visits up
to delivery and records were reviewed for any signs of development of PIH,
preterm delivery, low birth weight, placental abruption, recurrent pregnancy
losses, still birth, congenital anomalies, admission of baby to neonatal ICU,
foetal distress in labour and hyperbilirubinemia.
Estimation of TSH- The TSH assay was performed using the
TSH reagent Pack and Immuno diagnostic products TSH Calibrators on the ECi.
Immunodiagnostic System. An immunometric assay technique was used.
Serum, EDTA or heparin plasma was recommended.
Estimation of free T4- The free T4 assay was performed using
the free T4 calibrators on the ECi Immunodiagnostic system.
Statistical Analysis- For
statistical analysis Percentage, Proportion, Chi square test were used.Once the
values of chi square-tests are calculated the corresponding values of 'p' will
be obtained using the standard tales are per degree of freedom and the
significance graded as:
p value Results significance
<
0.05 to 0.01 statistically
significant
Results
Table-1: Distribution of cases according to
association with PIH in patients
|
Variable |
Control group (n=81) |
Study group (n=19) |
P Value |
|
|
PIH |
Present |
17 (20.9%) |
9 (47.36%) |
0.01 |
|
Not present |
64 (79.1%) |
10 (52.63%) |
||
The patients (n=100) were
divided into 2 groups: Control group & Study group. In control group, 17
(20.90%) of patients had PIH whereas in study group 9 (47.36%) had PIH. The
difference between both groups was statistically significant in relation to the
presence/absence of PIH.
Table-2: Association
of hypothyroidism with Bad Obstetric History & Diabetes
|
Risk Factor |
Control group (n=81) |
Study group (n=19) |
P Value |
|
|
Bad obstetric history |
Present |
13 (16.04%) |
7 (36.84%) |
0.04 |
|
Not present |
68 (83.95%) |
12 (63.16%) |
||
|
Diabetes |
Present |
1 (1.23%) |
2(10.5%) |
<0.05 |
|
Not present |
80 (98.76%) |
17(89.47%) |
||
Table 2 shows the
relationship of screening for detection of hypothyroidism with high risk
factor. Out of 100 patient underwent screening, 13patients from control group
and 7 patients from study group showed risk factor such as, bad obstetrics
history such as still birth or recurrent abortions. Diabetes was present in 1
patient from control group and in 2 patients from study group.
On statistical analysis
the correlation was found to be significant (p<0.05) patients with history
of Type-I DM and BOH.
Table-3: Distribution of cases according to
association with placental abruption
|
Variables |
Control group (n=81) |
Study group (n=19) |
P Value |
|
|
Placental abruption |
Present |
7 (8.68%) |
4 (21.1%) |
0.119 |
|
Absent |
74 (91.35%) |
15 (78.9%) |
||
|
Mode of delivery |
Vaginal delivery |
65 (80.24%) |
11 (57.89%) |
<0.05 |
|
Caesarean |
16 (19.76%) |
8 (42.11%) |
||
|
Gestational age of delivery |
<34 weeks |
8 (9.87%) |
8 (42.11%) |
0.03 |
|
>34 weeks |
73 (90.12%) |
11 (57.89%) |
||
|
Incidence of low birth weight |
<2 kg |
5 (6.17%) |
6 (31.6%) |
<0.002 |
|
2-2.5kg |
46 (56.8%) |
9 (47.1%) |
<0.005 |
|
|
>2.5 kg |
30 (37.1%) |
4 (21.1%) |
P > 0.05 |
|
Comparing the control
group and study group on the basis of distribution of cases, Placental
abruption was present in 7 (8.68%) patients of control group and 4 (21.1%)
patients of study group. There was a statistically significant difference
observed in Vaginal delivery and
Caesarean of both groups with p value<0.05 also, the difference was
significant for gestational age of delivery <34 weeks &>34 weeks in
both groups. As per the incidence of low birth weight, 5 patients of
Control group& 6 patients of study group has weight <2 kg, 46 patients
of Control group & 9 patients of study group has weight 2-2.5kg, 30
patients of Control group & 4 patients of study group has weight >2.5
kg.
Table-4: Relationship of hypothyroidism with foetal
distress in labour
|
Variables |
Control group (n=81) |
Study group (n=19) |
P Value |
|
Foetal distress, MSAF & other |
25 (30.86%) |
9 (47.36%) |
<0.05 |
|
No foetal distress |
56 (69.13%) |
10 (52.63%) |
Foetal distress, MSAF was
observed in 25 patients of control group and in 9 patients of study group. On
statistical analysis the result was found to be significant P < 0.05.
Table-5: Neonatal outcomes in patients with
hypothyroidism in comparison to normal patients
|
Outcome |
Control group (n=81) |
Study group (n=19) |
P Value |
|
Still birth |
2 (2.46%) |
3 (15.8%) |
<0.05 Z = 1.81 |
|
Congenital anomaly |
0 (0%) |
1 (5.3%) |
>0.05 |
|
Admission to ICU |
14 (17.3%) |
8 (42.1%) |
<0.05 Z = 2.03 |
|
Hyperbilirubinemia |
9 (11.11%) |
6 (31.57%) |
<0.05 |
On statistical analysis
the incidence of still births and ICU admission rates &hyperbilirubinemia
were found to be significant between two groups.
Considering the widespread
clinical implications of gestational hypothyroidism and its sequelae, the
present study was aimed to study the prevalence of hypothyroidism in pregnancy
and its feto-maternal outcomes. The study was carried out on 107 patients, who
presented to antenatal care in Subharti Hospital Dehradun over a period of one
year from 1st May 2015 to 30thApril 2016. The women were
followed up till delivery. The study population consisted of 81 normal patients
and 19 hypothyroid patients diagnosed and followed up. 7 hypothyroid patients
were dropped out from study. In our study, the prevalence of hypothyroidism
came out to be 24.29% while in a study by Saki F et al. found the prevalence of
hypothyroidism13.7% out of which 2.4% was clinical and 11.3% was sub-clinical [5].
Another study by Sahu HT et al. noted that the prevalence of thyroid
dysfunction was high, with subclinical hypothyroidism in 6.47% and overt
hypothyroidism in 4.58% women [6]. The variation in prevalence of
hypothyroidism may be due to difference in defined normal range of TSH.
Considering
the distribution of cases in study population, in the study group, 19 women were included,
these were the women who were diagnosed
as hypothyroid on the basis of serum TSH and Free T4 levels. In
control group, 81 women who had normal thyroid function test on screening. They
included the remaining 81 patients of study population.
Distribution
of cases according to association with PIH
The present study shows
47.36% cases of PIH in patients diagnosed as hypothyroidism patients in study
group compared to 20.9% incidence of PIH in patients in control group (P value
0.01- significant). Similar results were observed by Sahu HT, Das V Mittal et al
(2010), Aziz Nuzhat et al. in 2006,Kumar Ashok, Ghosh B.K. et al [6,7,8].
Relationship
of Screening for hypothyroidism with individual high risk factors
Positive correlation was
found between risk factors as bad obstetric history and Type - I diabetes. 35%
with BOH developed hypothyroidism which was statistically significant with
P<0.05.16 patients, out of 19 hypothyroid patients in the study group had
one or the other risk factor, whereas 3 patients (15.78%) were without any risk
factors.De vivo et al also found that the occurrence and timing of pregnancy
loss is related to hypothyroidism [9]. Bijay Viadyaet al. showed that the
prevalence of raised TSH was higher in the high risk group [10].
Study by Brain M. Casey,
Jodi S. Dash et al in 2005 showed that pregnancy in women with subclinical
hypothyroidism was three times more likely to be complicated by placental
abruption when compared with healthy pregnant women [11]. Similar results were
shown by Goel P, et al in their study on 30 patients with subclinical
hypothyroidism in 2005. They found an incidence of 0.3% placental abruption in
their study group which was not significant[12].
Comparison
of mode of delivery in the control and study groups
In the present study, we
found that 8 out of 19 (42.11%) in the study groupcompared to 16 of 81 (19.76%)
patients in the control group were delivered by caesarean section as on
statistical analysis the difference was significant (p<0.05). Comparable
results were shown in a study by Sahu HT, Das V Mittal et al (2010), Iskandar
Idris, Ramalingam Srinivasan et al. in 2005 [6,13].
Comparison
of preterm birth in control and study group
The present study showed
preterm birth defined as delivery before 34 weeks42.11% in the study group
compared to 9.87% of controls, which was found to be statistically significant
with p<0.05 (p value 0.003). Study by Brain M. Casey, Jodi S et al in 2005Aziz
Nuzhat, Reddi Pranathi et al in 2006 also showed increased incidence of preterm
delivery in hypothyroid group [7,14].
Comparison of cases according to birth weights
The present study showed
significant proportion of babies having low birth weight 31.6% of infants
weighed <2.0kg in the study group as compared to 6.17% of the control group
(p value 0.002). Similar results were observed in studies conducted by Aziz
Nuzhat et al., Idris I., Srinivasan et al[7,13]. Another similar study by Goel
P et al. showed 13.3% incidence of low birth weight with 20% evidence of foetal
distress[12].
Comparison of cases according to fetal distress
The present study showed
47.36% of study group having foetal distress in labour, 3 babies out of 19 had
still birth that is 15.8% and 1 out of 19 had congenital anomalies i.e.5.3%.
The foetal distress was found to be significant (p<0.05) in relation to the
control group and were comparable to the studies by Brain M Casey et al.which showed
that admission to the neonatal intensive care nursery and respiratory distress
were twice as likely in infants delivered of women with sub clinical
hypothyroidism [14]. Another similar study by Goel P et al. observed 13.3%
incidence of low birth weight and 20% had evidence of foetal distress [12].
Considering the above
feto-maternal complications the most practical approach is to screen all
pregnant women for hypothyroidism as early in pregnancy as possible (on before
conception). In the case of the mother, screening would result in early
diagnosis and treatment of hypothyroidism. The implications are staggering when
one considers that there is a significant increase in intrauterine deaths,
spontaneous abortions, premature births and pre-eclampsia in women with
gestational hypothyroidism.
In the infant, major
malformation and loss of IQ could be prevented by early diagnosis and treatment
of the mother. It is believed that if screening of all pregnant women in
implemented, the mother, the infant and society will all benefit.
A total of 107 patients
were included in the study and were screened by estimation of serum TSH and FT4
to determine the presence of hypothyroidism. Only 100 women were followed up
from their antenatal visit up till delivery Feto-maternal outcome of these
patients was recorded, while 7 were dropped out because of early pregnancy
loss. The salient observations made in this study are as follows:
·
The prevalence of hypothyroidism was 24.29% in this study.
·
The present study concluded that history of recurrent
pregnancy loss and diabetes are significantly associated with hypothyroidism.
·
The study showed that there was increased rate of gestational
hypertension, preeclampsia, preterm delivery and low birth weight babies in
hypothyroid group which was statistically significant.
·
The study also showed that rate of foetal distress during
labour (47.36% Vs 30.86%) was also high and hence rate of emergency caesarean
section (42.11 Vs 19.76%) was high in hypothyroid group. This value is also
statistically significant.
·
The study also showed that there was higher rate of still
births, hyper bilirubinaemia and admission to neonatal ICU (foetal distress,
meconium stained liquor) in the hypothyroid group.
What this study adds to
existing knowledge
The present study
therefore concludes that hypothyroidism continues to be an important medical
condition in pregnancy with significant feto-maternal
morbidity. This study therefore recommends that early identification and proper
management of this condition is the only intervention to ameliorate and
decrease is attendant morbidity and mortality.
How to cite this article?
Sharma V, Shukla N. Prevalence of hypothyroidism in pregnancy and its feto-maternal outcome. Obg Rev:J obstet Gynecol 2019;5(1):7-12.doi: 10.17511/jobg.2019.i1.02.