Pct transfers resulting in live births: This is the percentage of egg or embryo transfers that resulted in a live birth. The denominator for this measure includes the number of transfers described above. The numerator includes the live birth(s) that resulted from the transfer(s) of eggs or embryos. For example, if 60 intended retrievals were associated with 58 transfers within 12 months, which resulted in 30 live births, the average success rate per transfer would be 30 (live births) ÷ 58 (transfers) = 0.517, or 51.7% of transfers resulting in a live birth.

Number of transfers: This is the number of egg or embryo transfers where at least one egg was retrieved from the patient in 2016 and at least one egg or embryo was transferred within 12 months of the start of the cycle (in 2016 or 2017). The eggs or embryos can be either fresh or previously frozen and thawed.

Total number of cycles: This is the number of ART cycles started in 2017 by age group and in total. The total number of ART cycles is calculated as the sum of (1) the number of cycles started with the intent to freeze all resulting eggs or embryos (for example, short term banking or fertility preservation); (2) the number of cycles started with the intent to transfer fresh or frozen eggs retrieved from either the patient or donor; and (3) the number of cycles started with the intent to transfer fresh or frozen embryos created from fresh or frozen eggs retrieved from either the patient or donor.