The actual biological process of fertilizing an egg fails to produce a viable zygote a lot of the time. Fertilization happens but it immediately dies after. You just don't hear about it because there is no external way for a woman to know, but this is what is happening when you have anyone who has been trying to get pregnant for more than a couple months and the man isn't shooting blanks.
At the same time, successfully capturing an oocyte (egg) is difficult and harsh on the woman's body. So to ensure success, they usually harvest multiple eggs at the same time. The eggs get fertilized and they get screened for issues, and implantation involves a couple of the "best" eggs that are most likely to survive, and even then it's common for all but one to fail (even though it's still more common than in nature for multiple to survive, hence why IVF pregnancies have a relatively high rate of twins or more).
So you often end up with extras that are never going to be implanted in a uterus. There are a few choices to deal with them. 1. With parental consent, the fertilized eggs can be harvested as a source for stem cells. 2. The eggs are destroyed. 3. The eggs are permanently frozen.
It depends on the condition. Like, a guy might have sperm that don't swim but the DNA is fine. Or there could be a lack of chemotaxis due to something going with the sperm or the woman's body, so the sperm will be unable to hone in on the egg's location. There are a variety of ways a couple can have difficulty conceiving that IUI won't be able to help, but IUI is less invasive and less expensive than IVF so it's a good idea for people know their options before resorting to IVF.
The actual biological process of fertilizing an egg fails to produce a viable zygote a lot of the time. Fertilization happens but it immediately dies after. You just don't hear about it because there is no external way for a woman to know, but this is what is happening when you have anyone who has been trying to get pregnant for more than a couple months and the man isn't shooting blanks.
At the same time, successfully capturing an oocyte (egg) is difficult and harsh on the woman's body. So to ensure success, they usually harvest multiple eggs at the same time. The eggs get fertilized and they get screened for issues, and implantation involves a couple of the "best" eggs that are most likely to survive, and even then it's common for all but one to fail (even though it's still more common than in nature for multiple to survive, hence why IVF pregnancies have a relatively high rate of twins or more).
So you often end up with extras that are never going to be implanted in a uterus. There are a few choices to deal with them. 1. With parental consent, the fertilized eggs can be harvested as a source for stem cells. 2. The eggs are destroyed. 3. The eggs are permanently frozen.
This is why iui is the superior process but not as many ppl take it cause they think ivf is much more successful than it really is
It depends on the condition. Like, a guy might have sperm that don't swim but the DNA is fine. Or there could be a lack of chemotaxis due to something going with the sperm or the woman's body, so the sperm will be unable to hone in on the egg's location. There are a variety of ways a couple can have difficulty conceiving that IUI won't be able to help, but IUI is less invasive and less expensive than IVF so it's a good idea for people know their options before resorting to IVF.