There are various ways to present pregnancy rates:
- The chance of a birth from a single completed treatment. We consider a completed treatment as an IVF cycle with egg collection, or a donor cycle with insemination.
- The chance of a clinical pregnancy from a single treatment. A clinical pregnancy is the presence of a fetal sac on ultrasound early in pregnancy, so excludes most miscarriages. Clinical pregnancy rates are used for recent data, since it takes at least 9 months to collect birth outcomes.
- Cumulative pregnancy rates, which is the overall chance of a birth. For instance, from the use of all the fresh and frozen embryos from an IVF cycle, or from several cycles of treatment.
- It can be useful to compare pregnancy rates with treatment with those of fertile people. As a yardstick, we use a birth rate of 20% per month for fertile women 37 and younger.