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?


1 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.

  • $\begingroup$ There are several articles like that one, how about this one, it seems to say spontaneous movements at week 10-21 are movements generated by the fetus itself: karger.com/Article/Pdf/293158 "Fetal movements (FM) may be spontaneous, originating in the fetus itself, or evoked, caused by external stimuli. The FM in 21 normal twin pregnancies at 10 and 21 weeks of gestation were studied. The percentage rate of evoked FM which occur simultaneously in both twins was 4.96% of all observed FM. The rate of the spontaneous FM which occur independently in each fetus was 95.04% of all FM" $\endgroup$
    – Pablo
    Dec 21, 2018 at 20:14

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