If progesterone is absent or levels are too low, irregular and heavy menstrual bleeding can occur. A drop in progesterone during pregnancy can result in a miscarriage and early labour. Mothers at risk of giving birth too soon can be given a synthetic form of progesterone to delay the onset of labour.

the 2nd answer is this

If a poor-quality egg is fertilized, either the embryo is unable to implant, or the embryo initially implants, but is unable to develop properly, resulting in a subsequent miscarriage.

the 3rd answer is this

An embryo with genetic abnormalities can form a blastocyst (embryo at day 5 or 6) and be transferred to the uterus but will later miscarry.

the 4th answer is this..

it will lead to anolvulation

the 5th answer is this

In case the blastocyst does not implant, the lining of the uterus (endometrium) makes arrangements for the developing blastocyst to connect to it through many internal changes. Without these changes, implantation will not occur, and the embryo sheds off during menstruation

Explanation:

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