Pregnancy:

• Some finger-like projections appear on the trophoblast called chorionic villi which are surrounded by the uterine tissue and maternal blood.
• The chorionic villi and uterine tissue jointly form a structural and functional unit between developing embryo (foetus) and maternal body called placenta.

Stem cells: The inner cell mass contains certain cells called stem cells which have the potency to give rise to all the tissues and organs.

Gestation period: The average duration of human pregnancy is about 9 months and this period is known as gestation period.

Functions of Placenta: It has duel function,

 1) The placenta facilitate the supply of oxygen and nutrients to the embryo and also removal of carbon dioxide and excretory/waste materials produced by the embryo.

2) Placenta also acts as an endocrine tissue and produces several hormones like human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens, progestogens, etc.

Role of hormones released by placenta during pregnancy:

1) Human chorionic gonadotropin (hCG): It makes the graffian follicle to secrate progesterone which in tern makes the endometrium thick, suitable for pregnancy.

2) Oxytocin: Also called birth hormone, causes strong contractions of endometrium of uterus for parturition and milk production after birth.

Role of hormone released by ovary during pregnancy:

Relaxin: It softens and widens the pelvis for easy delievery.

Function of umbilical cord:

• The placenta is connected to the embryo through an umbilical cord which helps in the transport of substances to and from the embryo.

Indication of pregnancy by HCG test:

• Human chorionic gonadotrophin test is a pregnancy test, indicated by the presence of HCG hormone in female urine because of its high secretion during pregnancy. Due to this, pregnancy kit shows red colour as a positive result.

Common Reason of miscarriage:

• Mostly chromosome abnormality is the reason of early miscarriage but mental stress, any injury to developing foetus or many reasons can also cause this problem.

Perfect time of MTP (Medical termination of pregnancy):

• It is safe only till 3 months of pregnancy, but after this period, MTPs are considered unsafe for mother.