Objective: To report utilization, effectiveness, and safety of assisted reproductive technologies in 2015 and 2016., Design: A retrospective, cross-sectional survey of 3,103 assisted reproductive technology clinics in 74 countries in 2015 and 3,249 clinics in 79 countries in 2016 that submitted cycle and pregnancy outcome data through national and regional registries., Setting: Seventy-nine countries and >3,000 assisted reproductive technology clinics., Patient(s): Patients undergoing assisted reproductive technology procedures., Intervention(s): Assisted reproductive technology., Main Outcome Measure(s): Outcomes on country, regional, and global levels., Result(s): Reported for 2015: 2,358,239 cycles with 548,652 infants born; for 2016: 2,807,963 cycles with 647,188 infants born. Estimated in 2015, ≥2,683,677 cycles resulted in >675,134 infants; in 2016, ≥3,100,448 cycles resulted in ≥723,026 infants. Reported cycles represent approximately 80% of global utilization. In 2015 and 2016, 27.6% and 27.8%, respectively, of women undergoing fresh autologous treatment cycles were aged ≥40 years. Frozen-thawed embryo transfer (ET) cycles accounted for 47.0% and 51.9%, respectively, of all ETs in 2015 and 2016. Oocyte donation cycles accounted for 6.7% and 7.1% of all ETs in 2015 and 2016. Intracytoplasmic sperm injection was performed in 57.7% and 56.4% of autologous aspiration cycles in 2015 and 2016, respectively. The cumulative delivery rate per aspiration cycle for fresh and frozen-thawed ET was 32.4% in 2015 and 33.1% in 2016, respectively. The average number of transferred embryos was 1.70 in 2015 and 1.69 in 2016. The proportion of single ETs in fresh autologous cycles increased from 42.1% in 2015 to 44.0% in 2016. The twin delivery rate decreased from 16.0% in 2015 to 14.7% in 2016, and the triplet rate decreased from 0.6% in 2015 to 0.4% in 2016. The proportion of single ETs in frozen-thawed ET autologous treatment cycles was 62.2% in 2015 and 64.2% in 2016, with twin and triplet rates of 10.1% and 0.3% in 2015 and 10.0% and 0.2% in 2016, respectively., Conclusion(s): Utilization of assisted reproductive technology treatment and births per cycle increased from 2015 to 2016, although multiple births were reduced. An increasing proportion of frozen-thawed ET cycles, continuing wide variation in use of intracytoplasmic sperm injection, and an increase in single ET rates are reported., Competing Interests: Declaration of Interests M.S.K. reports travel support from Ferring, IBSA, and Merck, outside the submitted work. G.M.C. reports funding from the International Committee for Monitoring Assisted Reproductive Technologies (ICMART). The National Perinatal Epidemiology and Statistics Unit (NPESU) of the University of New South Wales, Sydney (UNSW) received funding. S.D. has nothing to disclose. F.Z.H. reports travel expenses to give a scientific lecture from Ferring Pharma, Director, responsible for the Latin American Registry of ART, Chair Committee of Ethics and Public Policies; Chilean Society of Obstetrics and Gynecology, Vice Chair ICMART, outside the submitted work. J.D.M. is Chair of Société de Médecine de la Reproduction, France, unpaid, outside the submitted work. O.I. has nothing to disclose. M.B. reports consulting fees from ABBOTT INIDA; honoraria from BAZEL PHARMA and MERCK SPEC; Board of Director, Pacific Rim Society of Reproductive Medicine; Board of Director, POSEIDON Group; Regional Director, IFFS Triennial Report, outside the submitted work. S.C.J. reports travel fee for lectures supported by Ferring; travel support from the Japan Society for Reproductive Medicine for attending meetings, outside the submitted work. B.F. has nothing to disclose. E.E. has nothing to disclose. V.B. reports consulting fees from Organon, Society for Assisted Reproductive Technology Executive Council, not paid, outside the submitted work. G.D.A. reports honoraria from Organon; travel support from ESHRE; Chair, International Committee for Monitoring ART. unpaid; President, World Endometriosis Research Foundation, unpaid; ICMART NGO Liaison Observer, Board of the International Federation of Fertility Societies, unpaid; ASRM: Member, Global Health Committee, American Society for Reproductive Medicine, unpaid; founder and CEO of Advanced Reproductive Care, Inc. (d/b/a ARC®Fertility), outside the submitted work., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)