Just to level set, here’s how i think IVF typically works. People who have actually been through it or have medical knowledge, please correct me.
1: the woman undergoes painful and risky hormonal manipulation to simultaneously ripen several eggs at once. Her risk continues for a while after the eggs are removed – i just spent a dance weekend organized by a woman who couldn’t dance at it, because her ovaries were still swollen from this procedure, and the doctor didn’t want her to engage in anything that jostled the ovaries.
2: ripe eggs are extracted with a needle, using some kind of imaging.
3: the eggs are fertilized with sperm that was collected in a way that’s icky, but not dangerous or painful to the man. 
4: the resulting zygotes are examined to see if they look healthy. Any that look good are frozen.
Freezing kills some of the zygotes. But the success rate using defrosted zygotes is higher than with fresh ones, and apparently, it’s basically a wash in terms of total viable zygotes. Last i read, it was felt that freezing was a decent proxy for testing the viability of zygotes.
5: the woman undergoes different painful and risky hormonal treatments to prepare the womb for implantation.
6: when the time is right, if all looks good, a zygote is defrosted and popped into the oven. The woman is then instructed to lie on her back for a while “to let gravity do the rest”.
They used to insert multiple zygotes at once, but i think it’s now considered unethical to implant more than 2 at a time, and most places do 1 at a time, at least among my friends.
After than, it’s pretty much like a normal pregnancy with a lot of monitoring.
The remaining zygotes can be stored in the freezer for a long time.