Pregnancy rate is the success rate for getting pregnant. It is the percentage of all attempts that leads to pregnancy, with attempts generally referring to menstrual cycles where insemination or any artificial equivalent is used, which may be simple artificial insemination (AI) or AI with additional in vitro fertilization.
There is no universally accepted definition of the term. Thus in IVF pregnancy rates may be based on initiated treatment cycles, cycles that underwent oocyte retrieval, or cycles where an embryo transfer was performed. In terms of outcome, "pregnancy" may refer to a positive pregnancy test, evidence of a pregnancy with a "viable" fetus or implantation. Furthermore, pregnancy rates can be influenced in IVF by transferring multiple embryos that may result in multiple births. A strict definition in the IVF setting would refer to the singleton pregnancy rate that determines how many live singletons are born in relation to initiated IVF cycles.
In some cases, success rates include delivery or presence of a live baby (preferably specified as delivery rate or live birth rate respectively).
Implantation rate is the percentage of embryos which are implanted compared to the number of embryos transferred in a given period. It represents the capacity of each embryo transferred during this period to implant in the uterus and to result in pregnancy.
Live birth rate
Live birth rate is the percentage of all cycles that lead to live birth, and is the pregnancy rate adjusted for miscarriages and stillbirths. For instance, in 2007, Canadian clinics reported a live birth rate of 27% with in vitro fertilisation. 
In IVF or its derivatives, fertilization rate may be used to measure how many oocytes become fertilized by sperm cells. A fertilization rate of zero in one cycle, where no oocytes become fertilized, is termed a total fertilization failure. Repeated ICSI treatment may be useful or necessary in couples with total fertilization failure.
Pregnancy rate for AI
Pregnancy rate for IVF
With enhanced technology, the pregnancy rates are substantially higher today than a couple of years ago. In 2006, Canadian clinics reported an average pregnancy rate of 35%. 
- Success rates explained Centre for medically assisted procreation. December 25, 2012 at 1:23 PM EST
- Success rate climbs for in vitro fertilization The Canadian Press. December 15, 2008 at 8:27 PM EST
- Liu J, Nagy Z, Joris H, et al. (October 1995). "Analysis of 76 total fertilization failure cycles out of 2732 intracytoplasmic sperm injection cycles". Hum. Reprod. 10 (10): 2630–6. PMID 8567783.
- Utrecht CS News Subject: Infertility FAQ (part 4/4)