BB,
This qn I know cos that is wat will happen, if egg quality or sperm quality are no good, it will definitely affect the growth, in fact, if it is really no good, then your body will react to it and terminate the pregnant, meaning miscarriage, that is what happen to me twice I suspect. Dr did a test for me after he performed D&C for me, the XY chromosomes were not normal, instead of a pair, I have got two pairs, so that's why it stop growing and the reasons are due to generic problem, quality of egg and sperm or just a one time unlucky chance that quality of egg and sperm leads to that.
However what I am saying is since in the lab, your egg and sperm can form embryos right, so when put in, it will get implanted if the linning or womb condition is good, assuming that the quality of sperm or egg are no good, it will still get implant first since they are already formed embryos but will stop growing at further stage lor, usually depending on how abnormal it is, can be like only after 6 weeks, then you cannot detect heartbeat and must to terminate it. so in IVF, you can still get preggy and just like other natural pregancy, still have risk of miscarriges lor.
I do have concern that even if I get pregnant which I did twice, will the pregnancy advance further? until I see the bb's heartbeat and foetus formed, then at least I can rest my heart abit, cos of my history.