A breaking new study has found that preborn babies in the first trimester have “adult-like” patterns of nerves. Researchers “combined whole-mount immunostaining, 3DISCO clearing, and light-sheet imaging to start building a 3D cellular map” and found that “the adult-like pattern of skin innervation is established before the end of the first trimester, showing important intra- and inter-individual variations in nerve branches.” They also found evidence for “a differential vascularization of the male and female genital tracts concomitant with sex determination.” The full study can be seen here.
For now, it’s almost conclusively provable that preborn babies can feel pain at 20 weeks gestation, although they respond to touch as early as eight weeks. There is also increasing evidence that preborn babies can feel pain much earlier than 20 weeks — possibly as early as five weeks. Some evidence exists to show that fetal pain may be even worse in the first trimester, “due to the uneven maturation of fetal neurophysiology.”
Read more at liveaction.org