hCG is a hormone of great importance in maintenance and establishment of human pregnancy. It is composed of 2 subunits and exists in four forms. It is mainly secreted from syncytiotrophoblast and also from the pituitary gland. It play a very crucial role in maintaining the pregnancy, promote angiogenesis and placental growth as well. If some sort of disturbances occur in the level of hCG it promote a lot of problem like preeclampsia, miscarriages and fetal growth retardation etc.

1. University of Chakwal, Pakistan

2. Topic: Disturbances in hCG Hormone
Secretion
Department of Zoology
Presented By: Shamza Shahid
Roll no# 20M-UOC/ZOL-42
BS Zoology
Session: 2020-2024
Subject: Endocrinology
Instructor Name: Dr. Syeda Nadia Ahmad

3. Introduction
• hCG stands for Human chorionic gonadotropin hormone.
• It is the hormone of great importance in establishment and
maintenance of human pregnancy.
• hCG exerts a lots of endocrine, autocrine and paracrine functions
on variety of cells and tissues ( Paulesu et al. 2018).

4. Structure
• hCG is glycoprotein hormone and ranges from 36 to 41kDa.
• It consists of 2 subunits, one is α subunit and other is β subunits
that are linked with non-covalent bond.
• The hormone hCG is specifically present in humans, while eCG
is specific for equines species.
• In other mammals, this hormone is replaced by LH hormone
(d’Hauterive et al., 2022).

5. Figure: 1.1: Structure of hCG Hormone
(https://www.mdpi.com/1422-0067/23/3/1380)

6. Isoforms
• It exists in four forms:
➢Classical hCG
➢Hyperglycosylated hCG
➢Free β unit of hyperglycosylated hCG
➢Sulphated hCG
• All these forms have different functions ( d’Hauterive et al.,
2022).

7. Figure: 1.2: Functions of four different hCG isoforms in pregnant and
non-pregnant women (https://www.mdpi.com/1422-0067/18/10/2037).

8. Brief History
• 1912, Aschner stimulate guinea pig’s genital tract with some
water-soluble extracts that are taken from human placenta.
• 1913, Fellner induce the process of ovulation in rabbits that are
immature with saline extract that are also taken from human
placenta.
• 1919, through human placental tissues Hirose stimulate ovulation
and luteal function in immature rabbits ( Cole, 2010).

9. Brief History
• 1927, Ascheim and Zondek found that pregnant women stimulate
some gonad stimulating substance.
• They experiment on immature mice and inject this substance into
the body of that mice and the because of this substance ovulation
and some other processes start working.
• Through this it is named as human chorionic gonadotropin,
chorion comes form latin word chordata and gonadotropin is
because it is some gonad stimulating substance ( Cole, 2010).

10. Secretions
• hCG hormone is mainly secreted by
syncytiotrophoblast after implantation.
• Its concentration can be measured in
maternal blood 10 days after the
ovulation process.
• During first trimester, its level rises.
• At the 19th week its level decreases
downward ( Gridelet et al., 2020).
Figure:1.3: Beta hCG secretions
(https://labpedia.net/beta-hcg-level-%CE%B2-
hcg-human-chorionic-gonadotropin-hcg/)

11. Figure:1.4: Beta hCG Formation (https://labpedia.net/beta-hcg-
level-%CE%B2-hcg-human-chorionic-gonadotropin-hcg)

12. Hypothalamus Pituitary hCG Axis
Figure: 1.5: Hypothalmic-Pituitary-hCG Axis (https://www.researchgate.net/figure/Pituitary-
hCG-production-The-release-of-hCG-from-the-pituitary-gland-may-be-due-to_fig1_5821758).

13. hCG Tests
• There are two tests for checking
the level of hCG in women:
i. hCG Urine Test
ii. hCG Blood Test.
(https://www.mountsinai.org/health-
library/tests/hcg-blood-test-
quantitative).
Figure:1.6: hCG level
(https://premom.com/blogs/get-pregnant/hcg-
levels-in-early-pregnancy).

14. Role Of hCG During Pregnancy
• It play a very crucial role in human pregnancy.
• It induce ovulation, maintain corpus luteum and also stimulate the
progesterone production.
• Inhibit myometrial contractivity, promote angiogenesis, stimulate
umbilical circulation and also promote the placental growth.
• It is also been shown that many fetal organs like lungs, kidneys etc have
some LH/hCG receptors but these receptors are not present in adults
organs (Paulesu et al., 2018).

15. hCG and Miscarriages
• The hCG molecule is involved in the fetal-placental-maternal unit.
• It is also potential biomarker for preeclampsia and also in the
gestational trophoblastic disease.
• Spontaneous abortions is the most common complication in early
pregnancy.
• Scientists found that in these women the level of hCG and Treg
cells are reduced as compared to the normal pregnant women
(d’Hauterive et al., 2022).

16. hCG and Thyroid Function
• hCG and TSH have same alpha subunit.
• hCG and thyroid functioning are correlated with each other.
• Low maternal thyroid function and the impaired thyroid response
stimulate hCG and they are used to lower fetal growth restrictions
and adverse effects of pregnancy.
• The patients with low β-hCG level and thyroid autoimmunity may
have the high miscarriages rate ( d’Hauterive et al., 2022).

17. Environmental Contaminants in Human
Pregnancy
• ECDs concentration may harm
the placental development and
also alter the hCG secretion.
• These changes may cause alot of
pregnancy and fetal disorders
(Paulesu et al., 2018). Figure: 1.7: Effects of Environmental Contaminants
(https://www.mdpi.com/1422-0067/19/3/914).

18. Emesis Gravidarum
• It is the most common complaint by the
pregnant women and also known by the term
“morning sickness”
• It happened to almost 35-91% on pregnancy
and 0.3-3.6% have some severe condition
known as “hyperemesis gravidarum”.
• The pregnant women have nausea without
vomiting and this condition most often leads
to the third trimester (Suhaid et al., 2022).
Figure:1.8: Average rate of β
HCG Hormonal Level to
Gestational Age (Suhaid et al.,
2022).

19. References
d’Hauterive, S. P., Close, R., Gridelet, V., Mawet, M., Nisolle, M., & Geenen, V.
(2022). Human chorionic gonadotropin and early embryogenesis. International
Journal of Molecular Sciences, 23(3), 1380.
Gridelet, V., Perrier d'Hauterive, S., Polese, B., Foidart, J. M., Nisolle, M., &
Geenen, V. (2020). Human chorionic gonadotrophin: new pleiotropic functions for
an “old” hormone during pregnancy. Frontiers in immunology, 11, 343.
Suhaid, D. N., Sunjaya, D. K., Lubis, V. M. T., Husin, F., Mose, J. C., & Setyono, I.
L. (2022). Relationship Between Beta HCG Hormone Levels, Anxiety and Stress
With Severe Degrees of Emesis Gravidarum. GSC Biological and Pharmaceutical
Sciences, 18(3), 054-062.