Why the women got pregnant?

Answer 1

At a time in the menstrual cycle of the females , ovulation occurs ;

If sexual intercourse occurs at this time , the sperms from a male mostly fertilize the female's egg cell ( Fertilization has occurred) ;

So a zygote forms in the oviduct , which moves along it to be implanted in the walls of the Uterus ( Endometrium ) , so the Corpus Leuteum keeps on secreting progesterone to maintain the thickened walls of the Uterus .

Consequently , The walls of the Uterus don't break down , because a Blastula was implanted in it earlier , so pregnancy starts , and the placenta starts to form .