Placental Hormones

Placental hormones are transporting molecules between mother and fetus, the placenta is a major endocrine organ. It turns out that the placenta synthesizes a huge and diverse number of hormones and cytokines that have major influences on ovarian, uterine, mammary and fetal physiology.

Types of placental hormones

There are two types of placental hormones

1.     Protein hormones

Several protein and peptide hormones are synthesized in placenta of various species, including

Ø  Human chronic gonadotrophin (hCG)

Ø  Human chronic somatotrophin (hCS)

Ø  Human placental lactigen (hPL)

Ø  Human chronic adrenocorticotropin (hACTH)

Ø  TSH

Ø  Melanocyte stimulating hormone

Ø  Relaxin

Ø  Oxytocin

2.     Steroid hormones

Sex steroids are the best known examples of placental hormones including

Ø  Estrogens

Ø  Progesterone

a)    Human chronic gonadotrophin (hCG)

HCG is a glycoprotein hormone which is produced during pregnancy by the embryo shortly after conception and later in large amounts, by the placenta.

Reference range:

Ø  In males < 5.0 mlU/ml

Ø  Non pregnant females < 5.0 mlU/ml

Ø  In about 85 percent of pregnancies hCG levels will double every two to three days.

Ø  hCG levels during pregnancy in weeks since last menstrual period,

Ø  3 weeks LMP 5 -50 mlU/ml, 4 weeks LMP 5 -426 mlU/ml, 5 weeks LMP 18 – 7340 mlU/ml, 6 weeksLMP 1080 -56500 mlU/ml, 7 – 8 weeks LMP 7650 – 229000 mIU/ml, 9 – 12 weeks LMP 25700 – 288000 mIU/ml, 13 – 16 weeks LMP 13300 – 254000 mIU/ml, 17 – 24 weeks LMP 4060 – 165400mIU/ml, 25 – 40 weeks LMP 3640 – 117000 mIU/ml.

Structure

Human chorionic gonadotropin is a glycoprotein composed of 244 amino acids with a molecular mass of 36.7kDa.

It is heterodimeric, with α (alpha) subunit.

Functions

Ø  The human chorionic gonadotropin plays a role in maintaining the secretion of progesterone, which thickens the walls of the uterus by keeping the corpus leutum from disintegration.