STUDY QUESTION: Does female weekly alcohol intake and binge drinking impact the chance of a successful fertility treatment? SUMMARY ANSWER: Low-to-moderate weekly alcohol drinking and binge drinking were not associated with the chance of achieving a clinical pregnancy or a live birth among women and couples undergoing medically assisted reproduction (MAR) treatments. WHAT IS KNOWN ALREADY: Alcohol consumption is common among women of reproductive age, even though health authorities advise women trying to conceive to abstain from drinking. A growing number of couples struggle with infertility, but it is unknown whether low-to-moderate levels of alcohol consumption and alcohol binge drinking impair success in fertility treatment. STUDY DESIGN, SIZE, DURATION: Cohort study with prospectively collected exposure information including 1708 women and potential partners undergoing fertility treatment at the public fertility clinic, Aarhus University Hospital, 1 January 2010 to 31 August 2015. In total, data on 1511 intrauterine insemination (IUI) cycles, 2870 in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycles and 1355 frozen embryo transfer cycles. PARTTICIPANTS/MATERIALS, SETTING, METHODS: Exposure to weekly average alcohol intake was assessed from questionnaires completed by participants before the start of treatment. Outcome measures are the achievement of a clinical pregnancy and live birth in consecutive treatment cycles in the Danish national health registries, enabling complete follow-up. A modified Poisson regression with robust standard errors was used to evaluate associations between a weekly average alcohol intake and MAR outcomes, adjusting for female age, body mass index, cigarette smoking, coffee consumption, chronic diseases, level of education, and cycle number. When evaluating the association between binge drinking in the month prior to baseline and MAR outcomes the analyses were further adjusted for average weekly alcohol consumption. MAIN RESULTS AND THE ROLE OF CHANCE: Low-to-moderate average weekly alcohol intake was not statistically significantly associated with the chance of achieving a clinical pregnancy or a live birth following IUI or IVF/ICSI treatment cycles. Compared to women abstaining from alcohol, the adjusted relative risks for achieving a live birth among those reporting 1-2, 3-7, and >7 drinks per week were 1.00 (95% CI 0.66; 1.53), 1.20 (0.76; 1.91), and 1.48 (0.56; 3.93), respectively, among women initiating IUI treatments. Among those initiating IVF/ICSI treatments, the chance for achieving a live birth among those reporting 1-2, 3-7, and >7 drinks per week were 1.00 (0.83; 1.21), 0.95 (0.75; 1.20), and 0.89 (0.53; 1.51), respectively. The chance of achieving a live birth in the first IUI or IVF/ICSI treatment cycle was unrelated to the number of binge drinking episodes in the month preceding baseline. LIMITATIONS, REASONS FOR CAUTION: The risk of non-differential exposure misclassification, confounding, or chance cannot be ruled out. In addition, due to the low number of women reporting an intake of >7 drinks/week, the potential effect of high alcohol consumption should be interpreted with caution. WIDER IMPLICATIONS OF THE FINDINGS: Although it remains unsettled if and how alcohol affects female reproduction, our results indicate that is not necessary to abstain from alcohol when striving for a successful outcome following fertility treatment. STUDY FUNDING/COMPETING INTEREST(S): J.L. is supported by a fully financed Ph.D. scholarship from Aarhus University and has received funds from the A.P. Møller foundation. The funding sources had no involvement in the conduct of the article. Dr Kesmodel reports personal fees from MSD and Ferring Pharmaceuticals outside the submitted work. All other authors have no conflicts of interest to declare and all have completed the ICMJE disclosure form. TRIAL REGISTRATION NUMBER: Not relevant.