In January 2016, Melissa Cook, a California gestational surrogate experiencing a multiple-birth pregnancy following the in vitro fertilization (IVF) transfer of three embryos comprised of donor eggs and sperm provided by the intended father, went to the media when the intended father requested that she undergo a fetal reduction because twins were less expensive to raise than triplets. Much of the legal interest in this case to date has centered on the enforceability of surrogacy contracts. However, the Cook case also raises troubling issues about fertility treatment practices involving gestational surrogates, twin preference, and third-party reproduction medical decision-making. This paper focuses on multiple-embryo transfers in the context of US surrogacy arrangements.Offering an original analysis of data obtained from the US national-assisted reproduction registry, it examines singleand multiple-embryo transfer trends over a 12-year period (2003 to 2014). Findings reveal that recommended guidelines were followed in fewer than 42% of the cases in 2014. The paper argues that ensuring equitable medical treatment for all recipients of IVF requires the adoption of treatment guidelines tailored to, and offering protections for, specific patient groups, and that, once in place, guidelines must be robustly implemented.