Profilaktik tibbiyot va salomlatlik
–
Профилактическая
медицина
и
здоровье
–
Preventive Medicine
and Health
Journal home page:
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The association between high hemoglobin levels and
pregnancy complications, gestational diabetes and
hypertension
Zukhra BEKTEMIROVA
1
Tashkent Pediatric Medical Institute
ARTICLE INFO
ABSTRACT
Article history:
Received September 2022
Received in revised form
10 October 2022
Accepted 25 November 2022
Available online
15 December 2022
Gestational diabetes mellitus (GDM) and hypertensive
disorders of pregnancy (HDP) are the principal causes of
maternal morbidity and mortality. The maternal morbidity and
mortality burden for women is relatively high, suggesting a
substandard quality of care. Therefore, an early diagnosis of
GDM and gestational hypertension (GH) can improve prenatal
care for pregnant women and improve pregnancy outcomes.
Previous studies demonstrated that elevated Hb levels in the
first trimester indicate possible pregnancy complications and
should not only be considered as good iron status. However,
ethnic differences could play a role in determining the
magnitude of the association. We hypothesized that high Hb
levels (≥12.5 g/dl) in the first trimester (6
-13 gestational
weeks, GW) are associated with an increased risk of fasting
blood sugar (FBS) ≥126 mg/dl, systolic blood pressure (SBP)
≥140 mmHg, and diastolic blood pressure (DBP) ≥90 mmHg
among pregnant women visiting prenatal clinics.
2181-3663
/©
2022 in Science LLC.
https://doi.org/10.47689/2181-3663-vol1-iss1-pp6
This is an open-access article under the Attribution 4.0 International
(CC BY 4.0) license (
https://creativecommons.org/licenses/by/4.0/deed.ru
Keywords:
maternal mortality,
maternal morbidity, fasting
blood sugar, high
hemoglobin level,
gestational hypertension,
gestational diabetes.
Yuqori gemoglobin darajasi va homiladorlik asoratlari,
homiladorlik diabeti va gipertenziya o'rtasidagi bog'liqlik
ANNOTATSIYA
Kalit so
‘
zlar:
onalar o'limi, onalar
kasallanishi, ochlik qon
Homiladorlik qandli diabet (GDM) va homiladorlikning
gipertonik kasalliklari (HDP) onalar kasallanishi va o'limining
asosiy sabablari hisoblanadi. Ayollar uchun onalar kasallanishi
1
Student, Tashkent Pediatric Medical Institute, Tashkent, Uzbekistan
E-mail: bektemirovazuxra741@gmail.com
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shakar, yuqori gemoglobin
darajasi, homiladorlik
gipertenziyasi, homiladorlik
qandli diabet.
va o'lim darajasi nisbatan yuqori, bu esa tibbiy xizmat sifatining
pastligidan dalolat beradi. Shuning uchun, GDM va homiladorlik
gipertenziyasi (GH) ning erta tashxisi homilador ayollarga
prenatal yordamni yaxshilash va homiladorlik natijalarini
yaxshilash mumkin. Oldingi tadqiqotlar shuni ko'rsatdiki,
birinchi trimestrda Hb darajasining oshishi homiladorlikning
mumkin bo'lgan asoratlarini ko'rsatadi va nafaqat yaxshi temir
holati deb hisoblanishi kerak. Biroq, etnik tafovutlar
uyushmaning hajmini aniqlashda rol o'ynashi mumkin. Birinchi
trimestrdagi yuqori Hb darajalari (≥12,5 g / dl) (6
-13
homiladorlik haftasi, GVt) ochlikdagi qon shakarining (FBS)
≥126 mg / dl, sistolik qon bosimi (SBP) xavfini oshirishi bilan
bog'liq deb taxmin qildik. Prenatal klinikalarga tashrif buyurgan
homilador ayollar orasida ≥140 mmHg va diastolik qon bosimi
(DBP) ≥90 mmHg
Связь между высоким уровнем гемоглобина и
осложнениями
беременности,
гестационным
диабетом и артериальной гипертензией
АННОТАЦИЯ
Ключевые слова:
материнская смертность,
материнская
заболеваемость, уровень
сахара в крови натощак,
высокий уровень
гемоглобина,
гестационная
гипертензия,
гестационный диабет
.
Гестационный сахарный диабет (ГСД) и гипертензивные
расстройства беременности (ГБН) являются основными
причинами материнской заболеваемости и смертности.
Бремя материнской заболеваемости и смертности среди
женщин относительно велико, что свидетельствует о низком
качестве медицинской помощи. Таким образом, ранняя
диагностика ГСД и гестационной гипертензии (ГГ) может
улучшить дородовой уход за беременными женщинами и
улучшить исходы беременности. Предыдущие исследования
показали, что повышенный уровень гемоглобина в первом
триместре
указывает
на
возможные
осложнения
беременности и не должен рассматриваться только как
хороший
статус железа. Однако этнические различия могут
играть роль в определении величины ассоциации. Мы
предположили, что высокие уровни Hb (≥12,5 г/дл) в первом
триместре (6
-
13 недель гестации, ГВ) связаны с повышенным
риском повышения уровня сахара в крови натощак (FBS)
≥126 мг/дл, систолического артериального давления (САД)
≥140 мм рт.ст. и диастолическое артериальное давление
(ДАД) ≥90 мм рт.ст. у беременных, посещающих женские
консультации
.
Introduction
Gestational diabetes mellitus (GDM) and gestational hypertension (GH)
significantly contribute to maternal, fetal, and neonatal morbidity and mortality [1].
The prevalence of GDM is rising worldwide and ranges from 1% to 20% [2]. During
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normal pregnancy, progressive insulin resistance develops during mid-pregnancy and
progresses through the third trimester [3]. Globally, hypertensive disorders of
pregnancy (HDP) are one of the leading causes of peripartum morbidity and mortality
[4]. HDP complicates up to 2.73% of all pregnancies and is responsible for 10-15% of
all maternal mortality [5]. It is associated with a spectrum of severity, ranging from
mild pregnancy-induced hypertension to eclampsia [5]. Moreover, it is among the most
significant and intriguing problems in obstetrics [5]. Women are at higher risk of
pregnancy complications due to the stressful life they live [6,7]. The burden of
maternal morbidity and mortality for women is relatively high, suggesting a problem
of substandard quality of care [6,7]. Moreover, HDP is under-treated among women
and is associated with an increased risk of cesarean section, preeclampsia (PE),
antepartum hemorrhage, postpartum hemorrhage, and chronic hypertension [8]. Early
diagnosis of GDM and GH can improve prenatal care for pregnant women during
pregnancy and result in a satisfactory pregnancy outcome [1].
Hemoglobin (Hb) measurement is a routine standard test for evaluating physical
status among pregnant women on their first visit to primary health care clinics [9].
Throughout normal pregnancy, blood volume expands by an average of 50%
compared with the non-pregnant state [10]. This rapid expansion of blood volume
starts in the first trimester of pregnancy [11]. Moreover, plasma volume increases
more than the increase in red blood cell (RBC) mass, which produces a net decline in
hemoglobin concentration during the first half of pregnancy. This is known as the
physiologic anemia of pregnancy [11]. Hb concentration reaches the nadir in the
second trimester of pregnancy because a concurrent increase does not match the
increase in plasma volume in RBC mass increase [12]. Based on the World Health
Organization (WHO), anemia in pregnancy has different cutoffs based on the trimester
(first trimester: <11.0 g/dl; second trimester: <10.5 g/dl; and third trimester: <11
g/dl) [13] while normal values are assigned from 11 to <12.5 g/dl [14]. Physicians and
health care providers give more attention to maternal anemia than high blood levels.
Previous studies demonstrated that elevated Hb levels in the first trimester indicate
possible pregnancy complications and should not be mistaken for good iron status [15-
22]. They also indicated that Hb levels during early pregnancy play a role in predicting
the risk of GDM and PE [16-19]. Studies which investigated the association between
high maternal Hb levels and adverse pregnancy outcomes are scarce and controversial,
with no absolute cut-off values for high Hb levels [15-22]. The cutoffs used to define
low or high hemoglobin concentrations in these studies differed considerably, which
may have affected the likelihood of detecting relations with the outcomes [21]. Most
often, only the most extreme cutoffs were significantly associated with pregnancy
complications.
Further research is necessary to study and better understand the heterogeneity in
the suggested cutoffs and risk factors associated with pregnancy outcomes. Moreover,
it was suggested that ethnic differences could play a role in determining the magnitude
of the association between high Hb and pregnancy complications [16]. Therefore,
further investigation in different ethnicities was recommended. Based on the literature
review, the assessment of high hemoglobin levels by which cutoff should be taken as
standard is still not clear. Taking into consideration the limitations of these studies, the
existing literature is insufficient. The adverse effects of high Hb at registration among
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pregnant women have not been previously investigated. Therefore, we conducted a
retrospective study to investigate the association between maternal Hb levels in the
first trimester (6-13 gestational weeks, GW) and adverse pregnancy outcomes (i.e.,
gestational hypertension and diabetes) among pregnant women. We hypothesized that
high Hb levels (≥12.5 g/dl) in the first trime
ster (6-13 GW) are associated with an
increased risk of fasting blood sugar (FBS) ≥126 mg/dl, systolic blood pressure (SBP)
≥140 mmHg, and diastolic blood pressure (DBP) ≥90 mmHg among pregnant women
visiting prenatal clinics from January 2018 to December 2019. The results of this study
could have important clinical implications for early screening, and improving
preventive and curative health services to promote healthy pregnant women.
Materials and methods
A cross-sectional study was performed in 2021 at primary healthcare centers. Low
Hb levels were defined according to WHO and CDC definition (Hb <11.0 g/dl) [13]
while normal Hb was defined as Hb ranging between 11.0 and 12.49 g/dl and high Hb
concentration ≥12.5 g/dl [14]. Based on WHO definition, fastin
g plasma glucose during
pregnancy ≥92 to <126 mg/dl (gestational diabetes) or fasting plasma glucose ≥126
mg/dl (diabetes mellitus) [23]. Other high biochemical and medical levels were
defined as the following: high systolic blood pressure ≥140 mmHg, and h
igh diastolic
blood pressure ≥90 mmHg. All medical records (N=5263) were reviewed for pregnant
women who attended primary healthcare centers of the MoH in these governorates in
the years 2018 and 2019. The year 2020 was excluded from the study due to the
COVID-19 pandemic and quarantine. Out of 5263 records, 2698 medical records were
excluded from this study as they met the exclusion criteria. Women were excluded if
they had a history of a current or previous diabetes mellitus (DM), GDM, abnormal
FBS, hypertension, GH, HDP, multi-pregnancies, and smoking during pregnancy. This
includes women who had: FBS ≥92 mg/dl or missing values for FBS (N=2096), blood
systolic blood pressure ≥140, diastolic blood pressure ≥90, or missing values for blood
pressure (N=292), missing hemoglobin values (N=21), ultrasound-based gestational
age more than 13 weeks (N=49), or who were previously diagnosed with
DM/GDM/hypertension/gestational hypertension, or taking drugs for these conditions
(N=240; Figure Figure11).
Figure 1
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Results
A total of (N=5263) medical records for pregnant women were collected, and 2698
records were excluded. The final number of eligible records was 2565. At registration,
the mean values for maternal age were 26.9±5.8 years, ultrasound
-based gestational
age (8.18 ±2.34 weeks), Hb level (11.87 ±1.17 g/dl), FBS (79.7 ±8.60 mg/dl), systolic
blood pressure (110.31 ±11.22 mmHg), and diastolic blood pressure (70.6 ±9.52
mmHg). At registration, 32.4% of the women had high Hb levels, 47.0% had normal Hb
levels, and 20.5% had low Hb levels. At 24 GW, 32.4% of the women had high Hb
levels, 45.5% had normal Hb levels, and 22.1% had low Hb levels. The percentage of
high FBS (≥126 mg/dl) at 24 GW was 4.4% and FBS (92 to <126 mg/dl) was 37.7%
while 58.2% had normal FBS (<92 mg/dl). As previously mentioned, women who had
FBS ≥92 mg/dl or systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90
mmHg either at registration or before that were excluded from this study.
Discussion
Management of pregnancy complications includes identifying and early
management of these complications and identifying high-risk patients. This study
aimed to investigate the association between high Hb levels at maternity care
registration and various adverse health outcomes later in pregnancy (GDM and high
blood pressure) among women attending primary care centers. In agreement with
previous studies, our results indicated that women who had high Hb (≥12.5 g/dl) at
registration were at higher risk to have high FBS (≥126 mg/dl) at 24 GW (OR 3
.39, p-
value <0.001) [16]. This association suggests that having a high Hb at registration in
the first trimester increases the risk of developing GDM later in pregnancy. The reason
for choosing 24 GW as a cutoff is that pregnant women at primary care centers get
screened for GDM at that gestational age, which is consistent with the international
recommendations [24]. These results could contribute to detecting high-risk
pregnancies at registration in the first trimester among women, therefore prompting
more intensive GDM risk factors modification and closer follow-ups than those with
normal Hb levels. Moreover, the biochemical basis of this association is probably due
to the effect of iron on decreasing insulin sensitivity by altering the expression of
insulin receptors in hepatocytes [25]. Further research exploring the impact of high Hb
in the first trimester on GDM will help better understand the etiology and
pathophysiology of GDM. This will ultimately lead to decreasing the consequences of
GDM, including high birth weight, shoulder dystocia, birth injuries, neonatal
hypoglycemia, and jaundice [26]. Moreover, pregnant women with high Hb in the first
trimester are three times more likely (OR=3.048) to have an increased risk of having
high systolic blood pr
essure (≥140 mmHg) at 24 GW (p
-value=0.014) but not high
diastolic blood pressure (p-value >0.05). This association between high Hb at
registration in the first trimester and increased risk of gestational hypertension is
consistent with a previous meta-analysis study [27]. However, that study confirms the
association without specifying the type of HDP (systolic/diastolic/mixed) [27].
Hypertensive disorders in pregnancy remain the leading cause of maternal mortality
worldwide [5]. Previous studies showed that high Hb levels during pregnancy result
from hypovolemia or hemoconcentration, which is usually the result of PE or
pregnancy-induced hypertension [10, 11]. An obvious mechanism for blood pressure
increase with increased Hb levels would be a result of the increased blood viscosity. It
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has been reported that the elevation of hematocrit and Hb levels increases blood
viscosity and that increased viscosity through an effect on blood pressure may partly
worsen cardiovascular function [28].
Conclusions
Women who have a high hemoglobin level in their first trimester are at a higher
risk of developing GDM and hypertension. Our findings suggest that the Hb level at
registration could be utilized in predicting the risk of GDM and HDP among women
who never had a previous history of these conditions. This early detection of high-risk
pregnancies could lead to more intensive follow-ups or interventions, ultimately
leading to decreased incidence and the adverse consequences of these conditions on
pregnant women. We recommend considering high Hb at registration among women
as a risk factor for having GDM and HDP later in pregnancy. Moreover, we recommend
conducting further research investigating the difference in adverse pregnancy
conditions prognosis (GDM and HDP) when considering high Hb at registration as a
risk factor compared to currently considered risk factors. Furthermore, since Hb
measurements are an inexpensive and widely available test, we recommend
conducting further research on the association between high maternal Hb and other
adverse outcomes and fetal complications among women. Further research is
warranted about the exact pathophysiology of high Hb-induced isolated systolic
hypertension and diabetes in pregnancy
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