An ongoing pregnancy is different from a clinical pregnancy in that it is one which has reached the second trimester and is therefore quite likely to result in a live birth. It is considered acceptable to state ongoing pregnancies in place of live births when quoting statistics from recent IVF cycles, in which some of the patients are still pregnant and the live birth rate is, thus, not known.

Thus, before you consider an IVF clinic’s success rates, you should take note of how they arrive at their rates. One clinic’s clinical pregnancies per embryo transfer cannot be compared with another’s live births per initiated cycle.

Further, see if the IVF program is including all of their data. For example, if they quote statistics only for "under 40" patients, the numbers will most likely be higher than if they include all age groups. And be sure that a program is presenting all their data, not just the selected months or years that they want you to see.

Be certain, also, that the data has been reported to (and thus verified by) SART.

Even armed with this knowledge, there is no way to truly compare one IVFclinic with another. Some will exclude potential IVF patients who are unlikely to succeed, which will make them appear to have better success rates than those who accept everyone who comes to them for help. Also, some may have more success with couples who have your particular condition than do others. In fact, the SART guidelines (Practice Committee Report: Guidelines for Advertising by ART Programs, January 1998) specifically caution their member clinics to make consumers aware that "as entry level criteria are highly variable for each program, a center-by-center comparison of results is not valid".