Research Article
Open Access
The Prevalence of Thyroid Dysfunction among Sudanese
Pregnant Women
Amel K. Saeed1, Khalid Yassin2, Elmahdi M A. Elmahdi3, Druce Maralyn4, AbdelAziem A. Ali5*
1Faculty of Medicine, Department of Medicine, Alneelain University, Sudan
2Faculty of Medicine, Department of Obstetrics and Gynecology, Alneelain University, Sudan
3Faculty of Medicine, Department of Medicine, Khartoum University, Sudan
4Bart's and the London school of Medicine, Department of Endocrinolgy, UK
5Faculty of Medicine, Department of Obstetrics and Gynecology, Kassala University, Sudan
*Corresponding author: Abdel Aziem A. Ali, P.O. Box 496, Department of Obstetrics and Gynecology, Faculty of Medicine, Kassala University, Kassala, Sudan,
Tel: +249912351175; Fax: +249411823501; E-mail:
@
Received: April 21, 2015; Accepted: May 25, 2015; Published: June 15, 2015
Citation: Saeed AK, Yassin K, Elmahdi EMA, Maralyn D, Ali AA (2015) The Prevalence of Thyroid Dysfunction among Sudanese
Pregnant Women. SOJ Gynecol Obstet Womens Health 1(1): 5. DOI:
http://dx.doi.org/10.15226/2381-2915/1/1/00103
Background: Thyroid dysfunctions are most prevalent in
women during their most fertile years (15-35), and for a long time
thyroid dysfunctions have been linked with poor reproductive health
and pregnancy outcomes.
Methods: All pregnant ladies- aged 15 to 45 years- who attended
ante-natal clinics in Al Amal National hospital and Ribat University
hospital, Khartoum, Sudan during the period of May-July 2014
were included to investigate the prevalence and risk of thyroid
dysfunctions, to determine trimester-specific reference ranges for
free Tri-Iodothyronine (FT3), Free Thyroxin (FT4) and Thyrotrophin
(TSH) among healthy pregnant Sudanese women. Chi square test and
logistic regression analyses were performed. Confidence intervals of
95% were calculated and P < 0.05 was considered significant.
Findings: During the study period a total of 500 pregnant women
were included, their mean age, duration of marriage and parity was
(26.43 ± 5.1) year, (5.378 ± 4.2) year and (2.8 ± 0.2) respectively. The
prevalence of thyroid dysfunctions among the respondents was 9.4%
(47/500). On further analysis and with regard to thyroid dysfunctions
3.4% of the women were found having hyperthyroidism, 2.8% was
hypothyroid, 1.8% had simple goitre and 1.4% were diagnosed and
treated as thyroiditis. Additionally, we found that 3% (15/500) of
our studied group have thyroid disorders which were discovered for
the first time after testing their thyroid functions during this study
while 6.4% (32/500) were diagnosed prior to our study. The average
ranges of TSH was (0.08-4.77 mIU/L), T3 (0.30-5.42 nmol /L) and T4
(0.16 - 4.70 pg ml) and there was slight fluctuation of the mean values
of thyroid hormones according to trimester in Euthyroid pregnant
women. Family history of autoimmune diseases (AID) (OR=11;
CI=, 1.1-66.5; P =0.033) and rural residence (OR=13.8; CI=3.5-56;
P =0.000) were significantly associated with thyroid dysfunctions
among our respondents.
Conclusions: We recommend investigation for thyroid function
test during pregnancy and in preconception clinics.
Keywords: Prevalence; Thyroid disease; Pregnancy; Sudan
Introduction
The thyroid gland plays a vital role in body metabolism,
through the production of thyroid hormones, which are known
to have important actions in controlling many of the human
reproductive functions [1]. Thyroid dysfunctions are most
prevalent in women during their most fertile years (15 - 35), and
for a long time thyroid dysfunctions have been linked with poor
reproductive health and pregnancy outcomes [2]. When a female
with an uncorrected thyroid dysfunction becomes pregnant, this
may have terrible adverse effects on fetal and maternal wellbeing,
particularly the neuro-intellectual development of the fetus
[3]. Thyroid gland diseases vary according to the environment,
diet, heredity and social background [4]. Iodine deficiency is
one of the commonest environmental factors responsible for
thyroid diseases, More than one billion persons are at risk of
iodine deficiency worldwide and 200 million have goitre [5].
In Sudan, iodine deficiency and endemic goitre and variable
thyroid dysfunctions are persistent health problems, with the
prevalence of goitre reaching up to 22% in some areas, (with a
range of 13% to 87% ) [5]. Although the salt iodination program
was introduced in Sudan as early as the 1970s the problem is still
there, and it is expected to affect mainly neonates, children and
young females. However, only a few studies have been conducted
on this issue in Sudan, most of them many years ago [5]. The
investigation and management of thyroid dysfunctions are not
considered in routine screening protocols of pregnant women,
or of those planning to get pregnant, even though missing the
diagnosis and the delay in managing the thyroid dysfunctions
has been proved to have a deleterious effect on the wellbeing
of mother and offspring. Thus this study was designed and
directed to investigate the prevalence of thyroid dysfunctions in
pregnancy and to provide the health planner with fundamental
data necessary for appropriate intervention.
Material and Methods
This was a cross sectional hospital based study designed to
investigate the prevalence and spectrum of thyroid dysfunctions among pregnant Sudanese females aged 15-45 years, to determine
the common types of thyroid dysfunctions among pregnant
ladies and to determine trimester-specific reference ranges
for free Tri-Iodothyronine (FT3), Free Thyroxine (FT4) and
Thyrotropin (TSH) among healthy pregnant Sudanese women.
All pregnant ladies- aged 15 to 45 years- who attended antenatal
clinics in Al Amal National hospital and Ribat University
hospital, Khartoum, capital city of Sudan during the period of
May-July 2014 and who agreed to participate in the study were
included. According to these criteria the total number of patients
attended the antenatal clinics during the period of the study were
518, but 12 declined to participate in the study, 6 patients were
excluded due to incomplete data and 500 were the final number
of participants. After we obtained signed informed consent
the data has been collected by direct interview with patients,
by four trained data collectors, using a detailed structured
questionnaire, covering socio-demographic information (age,
residence, education, and occupation), history of thyroid disease
and past medical history (diabetes mellitus, auto-immune
disease, hypertension...etc.). Also the questionnaire included
the obstetric (parity, history of miscarriage, stillbirth delivery,
preterm birth...etc.) and gynaecological (delay of conception,
irregular menstrual period) data. This was followed by, systemic
clinical examination and examination of the thyroid gland. 5 ml
of venous blood sample were collected from each participant to
evaluate the thyroid function; serum was separated immediately
by a fine centrifugation machine and sent for thyroid function
test. TSH, free T3 and free T4 were quantitatively determined
using Microparticle Enzyme Immunoassay (MEIA). We compared
the obstetric and gynaecological data and socio-demographic
characteristics between the women who were suffering
from thyroid dysfunction and those who were euthyroid. All
participants were under multidisciplinary care and were treated
according to their diagnosis.
The different variables were compared between the women
with thyroid dysfunction and euthyroid women. Proportions
were compared between the two groups of the study using
chi-square test. Univariate and multivariate analyses were
performed. Thyroid dysfunction was the dependent variable;
socio-demographic characteristics, obstetric and gynaecological
data were independent variables. Confidence intervals of 95%
were calculated and P < 0.05 was considered significant. In case of
discrepancy between the results of the univariate and the results
of multivariate analyses, the later was taken as final.
Results
Baseline Characteristics
During the study period a total of 500 pregnant women were
included, their mean age, duration of marriage and parity was
(26.43 ± 5.1) year, (5.378 ± 4.2) year and (2.8 ± 0.2) respectively.
The vast majority had completed university education (72.4%),
most of the women were housewives (85.4%) and the largest
group was coming from the urban regions of Sudan (55%).
Significant medical history and co-morbidity was found in 10 patients as follow: 6 (1.2%) patients with diabetes mellitus and 4
(0.8%) patients with hypertension. Thirteen women gave family
history of auto-immune disease.
Thyroid function among the investigated women
From the study, we found that the prevalence of thyroid
dysfunctions among Sudanese pregnant females evaluated for
thyroid dysfunction was 9.4% (47/500). On further analysis
and with regard to thyroid dysfunctions 3.4% of the women
were found having hyperthyroidism, 2.8% having hypothyroid,
1.8% having simple goitre and 1.4% were diagnosed and treated
as thyroiditis. Additionally, we found that 3% (15/500) of our
studied group have thyroid disorders which were discovered
for the first time after testing their thyroid functions during this
study while 6.4% (32/500) were diagnosed prior to our study.
Of the newly diagnosed group 80% (12/15), 13.3% (2/15) and
6.7% (1/15) has hyperthyroid, hypothyroid and simple goitre
respectively. Most of the respondents who were suffered from
thyroid dysfunction prior to this study had not had their thyroid
functions rechecked or corrected prior to conception (21/32,
65.6% ), and many were not on regular follow up or treatment at
the time of the study, and were still having active or uncontrolled
disease (19/32, 59.4% ). As one of our objectives was to try to
estimate the mean average of thyroid hormone levels among
healthy pregnant Sudanese females who have normal thyroid
function (according to the international values), we found the
average ranges of TSH was (0.08-4.77 mIU/L), T3 (0.30-5.42
nmol /L) and T4 (0.16 - 4.70 pg ml) Table 1. Also there was slight
fluctuation of the mean values of thyroid hormones according to
trimester in Euthyroid pregnant women as follow: T4 increased
by 0.2267 pg ml in the second trimester and by 0.0913 pg ml in
the third trimester while T3 dropped by 0.7814 nmol /L in the
second trimester and by 0.8867 nmol /L in the third trimester,
again TSH slightly dropped by 0.298 mIU/L and 0.2818 mIU/L in
the second and third trimesters respectively, Figure 1.
Obstetric and gynaecological data associated with
thyroid dysfunction
Among the patients with thyroid dysfunction (47 women)
17 (36.1%) gave history of miscarriage, 3 (6.4%), 1 (2.1%), 1
(2.1%), 6 (12.6%) and 4 (8.5%) gave history of preterm birth
delivery, stillbirth delivery, delivery of mentally retarded baby,
delay of conception and irregular menstrual cycle respectively.
In comparison with euthyroid women the study revealed that
the history of miscarriage was significantly associated with
thyroid dysfunction (36.1% Vs 18.3%, P=0.006), however our
study failed to demonstrate any statistical association between,
preterm birth delivery, stillbirth delivery, history of delivering
mentally retarded baby, history of delay to conceive (described
as inability to conceive for one year or more of unprotected
sexual intercourse) and history of irregular menstrual cycle and
thyroid disorders Table 2.
Risk factors for thyroid dysfunction
On trying to point out the possible risk factors for thyroid
Table 1: Thyroid hormone levels among Sudanese pregnant females with normal thyroid function – Sudan- 2014.
|
|
Test |
Mean ±SD |
Minimum |
Maximum
|
Level of thyroid hormones in all Euthyroid females |
|
TSH |
1.70±.89 |
0.08 |
4.77 |
T3 |
3.41 ±.89 |
0.30 |
5.42 |
T4 |
0.83±0.61 |
0.16 |
4.70 |
Level of thyroid hormones in Euthyroid females per trimester |
1st |
TSH |
1.793 ±0.89 |
0.30 |
4.24 |
T3 |
4.4469± 0.99 |
0.30 |
4.94 |
T4 |
0.803±0.8 |
0.44 |
4.70 |
2nd |
TSH |
1.4413±1.0 |
0.06 |
4.77 |
T3 |
3.6653±0.9 |
0.50 |
5.00 |
T4 |
1.03±.54 |
0.16 |
4.00 |
3rd |
TSH |
1.4575 ±1.03 |
0.06 |
9.34 |
T3 |
3.56±0.89 |
0.80 |
5.42 |
T4 |
0.8946± 0.58 |
0.27 |
4.70 |
Figure 1: Shows the fluctuation of the mean values of thyroid hormones according to trimester in Euthyroid pregnant Sudanese females- Sudan 2014.
Table 2: Comparison showing the obstetric outcome and gynecological
data between pregnant women with thyroid dysfunctions and euthroid
women, Sudan, 2014 using chi-square test.
Variable |
|
With thyroid dysfunction
(47) |
|
|
Euthroid
(N=453) |
|
P |
Miscarriage |
|
17(36.1%) |
|
|
83 (18.3%) |
|
0.006 |
|
|
|
|
|
|
|
|
Preterm birth |
|
3(6.4%) |
|
|
28 (6.1%) |
|
0.723 |
|
|
|
|
|
|
|
|
Stillbirth delivery |
|
1(2.1%) |
|
|
13(2.8%) |
|
0.272 |
|
|
|
|
|
|
|
|
Mentally retarded baby |
|
1 (2.1%) |
|
|
1 (0.2%) |
|
0.108 |
|
|
|
|
|
|
|
|
Delay of conception |
|
6 (12.6%)
|
|
|
42 (9.2%) |
|
0.140 |
|
|
|
|
|
|
|
|
Irregular cycle
|
|
4 (8.5%)
|
|
|
5 (1.1%)
|
|
0.001
|
dysfunctions among our patients, family history of autoimmune
diseases (AID) (OR=11; CI=, 1.1-66.5; P =0.033) and rural
residence (OR=13.8; CI=3.5-56; P =0.000) were significantly
associated with thyroid dysfunctions among our respondents,
Table 3.
Discussion
In this study we aimed to detect the prevalence of thyroid
dysfunctions during pregnancy, also, we tried to find out the
mean values and range of thyroid hormones in general and also
trimester specific levels in euthyroid healthy pregnant females.
The hypothyroidism which this study describes (2.8%) is in line
with what was observed in Gaza population (2.2%) and similar
to the prevalence rate of hypothyroidism among European
(2.2%) and American pregnant women (2.5%) [6]. On the other
hand, the prevalence of hyperthyroidism in our study was very
high (3.4%) as compared with other studies (Gaza 1.0 %) and
(1.3%) in Tunisia, but it is similar to review done by Daniel
(3-4% in all pregnant women) [7,8]. It might not be valid to
compare our results with results in the industrialized countries
because the magnitude and effect of iodine deficiency and other
environmental or genetic factors on thyroid function of pregnant
Sudanese females has never been studied seriously [5].
Although we found that 68.1% of patients with thyroid disease had been diagnosed previously, most of them had not had their
thyroid functions rechecked or corrected prior to conception, and
many were not on regular follow up or treatment at the time of
the study, and were still having active or uncontrolled disease. It
is highly recommended that all females with pre-existing thyroid
diseases should have their thyroid function rechecked and
normalized prior to conception, and thyroid functions monitored
throughout pregnancy, especially during the first 12 gestational
weeks when the maternal thyroid is solely responsible for
delivering thyroid hormone to the growing fetus, which is crucial
for its normal brain development [9].
Table 3: Risk factors for thyroid dysfunction among Sudanese pregnant women, 2014, using univariate and multivariate analyses
Variable |
Univariate analyses |
Multivariate analyses |
|
OR |
95% CI |
P-value |
OR |
95% CI |
P-value |
Age ≥ 35 |
1.0 |
1.0-1.1 |
0.043 |
1.1 |
1.0-1.1 |
0.034 |
Parity ≥ 5 |
1.1 |
0.9-1.2 |
0.221 |
0.9 |
0.6-1.2 |
0.771 |
Rural residence |
7.2 |
2.8-22 |
0.001 |
13.8 |
3.5-56 |
0.000 |
Comorbidity, yes |
1.1 |
0.4-2.8 |
0.758 |
1.7 |
0.4-6.4 |
0.403 |
Family history of AID |
7.5 |
1.6-36.1 |
0.010 |
11.0 |
1.1-66.5 |
0.033 |
In this study, we found that T3 dropped by 0.7814 nmol
/L in the second trimester and by 0.8867 nmol /L in the third
trimester. This is similar to the results found in a study done in
China where they found the highest level of FT3 was during the
first trimester [10], and in concordance with some other studies
in this field such as that done by Kurioka and his colleagues, who
reported significantly reduced levels of free T3 and free T4 during
pregnancy [11]. The mean T4 levels were estimated at 0.8033 in
the first trimester, increased to 1.03 in the second trimester and
to 0.8946 in the third trimester in the euthyroid group. Mean
TSH levels were 1.793 microlU/ ml in the first trimester, 1.4413
microlU/ml in the second trimester and 1.4575 microlU/ml in the
third trimester of pregnancy. Although slightly higher during first
trimester, these levels are still within the recommended levels of
the American Thyroid Association Task force on Thyroid Disease
during Pregnancy 2011 [12]. The reference range for TSH is
lower throughout pregnancy, in that both the lower normal limit
and the upper normal limit of serum TSH are decreased by about
0.1-0.2 mIU/L, and they recommended that if trimester-specific
reference ranges for TSH are not available in the laboratory,
the reference ranges recommended are: first trimester, 0.1-
2.5 mIU/L; second trimester, 0.2–3.0 mIU/L; third trimester,
0.3–3.0 mIU/L [12]. During normal pregnancy, significant but
reversible changes in thyroid function might occur as a result
of the normal physiological and hormonal changes, such as the
influence of the Human Chorionic Gonadotropin (HCG) as a weak
stimulus of thyroid hormones production resulting in subclinical
hyperthyroidism. Also, the high estrogen level increases serum
thyroid hormone binding proteins, with a consequent increase
of the total level of thyroid hormones. These possible changes
should be considered when interpreting the thyroid function test
during pregnancy [9]. In agreement with our results Stricker et al.
(Switzerland) and Soldin et al. (USA) observed similar fluctuation
in the trimester specific levels of thyroid hormones [13, 14]. Although there is still no strong evidence concerning the
effect of the thyroid disease on pregnancy there are clear data
confirmed that with thyroid dysfunction there is increase risk of
miscarriage, premature delivery, preeclampsia, low birth weight
[15-18]. Our study demonstrated significant association between
thyroid dysfunction and history of miscarriage. This fact might
be changed if the patients were adherent to the follow up and
preconception management. Interestingly thirteen women with
thyroid dysfunction gave family history of auto-immune disease
and there were 4 cases claimed that their menstrual period was
irregular. The immune system may produce antibodies against
the ovarian tissue, harming the egg-containing follicles and
damaging the egg [19]. What triggers the immune response is
unclear, but may be explained by being a multiple endocrinological
dysfunction. Among the different socio-demographic and risk
factors rural residence was found significantly associated with
thyroid disorders among the investigated pregnant women. This
might be attributed to change in diet and iodine intake; however
more research is needed to conclude an evidence for this factor.
Limitations
Limitation of this study is partly due to the small size sample
and being confined to only two hospitals which underestimate
the actual burden the problem. Also the study didn't consider the
iodine as an important element in thyroid function test.
Conclusions
Thyroid dysfunction is highly prevalent among Sudanese
pregnant women. There is slight fluctuation of thyroid hormones
during pregnancy in euthyroid women and thyroid dysfunction is
affected by rural residence and history of auto-immune disorder.
We recommend more researches in this field and advice routine
investigation for thyroid function test during pregnancy and in
preconception clinics.
Acknowledgement
We sincerely thank all women who participated in this study.
Ethical approval
The study approved and received ethical clearance from the
Research Board at Alneelain University, Sudan.
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