The zygote is implanted on the lining of the uterus and this provides nourishment to the zygote for a few days, so that it can give some time for the placenta to be formed. The uterus lining helps the zygote to stick to it because if by mistake it may fall off. 

When the placenta is formed it has blood spaces to the mother's side and to the baby's side there are blood vessels, the placenta even helps in taking away or throwing off the wastes generated by the baby.

Mark as brainliest if helpful.......
Yours, Jahnavi