On several occasions I have been "warned" by women that I need to watch out doing IVF because I may end up like Kate Goslin and have 6 babies at once.
First, don't issue advice unless you know what you are talking about.
Items 2 through 202 I will sum up below:
Kate from John and Kate Plus Eight did not do IVF. She did an IUI with injected super-ovulatory drugs. That means is the ONLY way you could unintentionally have greater than 2 babies. *
IVF uses super ovulatory drugs to stimulate as many eggs as possible, then the eggs are removed from the body, and fertilized in a petri dish. The women and doctor then CHOSE how many embryos are placed back in the body. Any leftovers are frozen for future use. Medical ethical guidelines dictate no more than 2 embies go back in the body for women under 35. If you have special medical reasons, or previous failed attempts the doctor may put more embies in, but you would always know and control the number.
IUI with superovulatory injections stimulates eggs that are left in the body and fertilized the good old fashioned way, or through an insemination. The doctor tries to control (via monitoring) how many actually mature. If your doctor tells you this can be perfectly controlled he is lying and you should leave that clinic. All of the "unintended" super multiples in the US due to fertility treatments have been due to accidents using this method. I have seen two excellent reproductive endocrinoligists who have both said the same thing: 5% of pregnancies using this method result in triplets or more, and from a medical health standpoint, these pregnancies are very dangerous, furthermore, all the monitoring in the world cannot predict when that 5% will take place. It is completely unpredictable. With one exception: If during monitoring you show that you have a huge amount of maturing follicles the responsible doc will not go through with the insemination due to the danger. Though responsible, this is a sad event for the patient, because they likely just blew a couple thousand dollars on those drugs.
The very start of infertility treatments (IF) is usually Chlomid, which is an injested drug, with side effects similar to birth control pills that stimulate natural ovulation, with a risk of two eggs at once. Many twins have been born due to Chlomid. There is no documented risk of <2 babies using Chlomid.
*Under any of these methods, there is the natural risk that the embryo could split, creating identical twins, so in theory, even if you did IVF, and chose to implant just two embryos, those embryos could twin. (or more) It is the same risk of identical multiples as in the general population and I have known of people who have wound up with three babies, 1fraternal baby plus identical twins.
All of this information is freely available on the internet. To the obnoxious "warners" out there: read up before you spread litter fear.