幼态延续（英语：Neoteny）又译作“幼态持续”，是指一个物种把幼年的甚至胎儿期的特征保留到幼年以后甚至成年期的现象。

幼态延续在演化过程中起到重要的作用，经过多世代演化，可以造成某种生物将幼态状态保持在成熟个体中，形成新的品种，这个过程是由于基因突变或基因之间互相作用造成的。例如：

Neoteny (/niːˈɒtᵻni/ /niːˈɒtni/ or /niːˈɒtəni/), also called juvenilization, is one of the two ways by which paedomorphism can arise. Paedomorphism or paedomorphosis is the retention by adults of traits previously seen only in the young, and is a subject studied in the field of developmental biology. Neoteny is found in modern humans. Paedomorphism can also be the retention of larval traits which is commonly studied in salamanders. In neoteny, the physiological (or somatic) development of an organism (typically an animal) is slowed or delayed. In contrast, in progenesis, sexual development occurs faster. Both processes result in paedomorphism, a type of heterochrony. Ultimately this process results in the retention, in the adults of a species, of juvenile physical characteristics well into maturity and pedogenesis (paedogenesis), or reproduction in a neotenized state.