What type of movement is "spontaneous movement" if it isnt reflex movement and it isnt purposive movement?

Question

According to Spontaneous and induced fetal activity

Spontaneous motor activity of the foetus depends significantly ot the foetal age; during the period between the 12th and 16th week it was recorded in 94.4%

By spontaneous, correct me if I wrong, I understand non reflexive movement and by induced I understand reflexive movement, since

A reflexive reaction or movement occurs immediately in response to something that happens.

But also, according to this other article Fetal movement

purposive movement begins at about 18 weeks, gradually replacing reflex movements

If "spontaneous movement" it isnt reflexive movement since it isnt an automatic reaction to something, and it isnt purposive movement, what is it exactly, and what does it generate it?

Answer 1

Although I can't read the original article in Czech, from their abstract it is clear that all they mean in differentiating spontaneous versus induced movement is whether the experimenter manipulated the uterus to induce a movement. Movements they observe could still be reflexive, they make no distinction of the type of movement (and do not intend do) except indicating whether the movement was purposefully caused by the experimenter.