The layout of fingerprint patterns is finalized about 16 weeks after conception. (LeVay, Simon and Janice Baldwin. Human Sexuality. p 108-109. MA:Sinauer Associates, Inc., Third Edition, 2009.)
By the 4th month after conception, the fetus is able to hear. (Tomatis, Alfred A, M.D. Editor Timothy M. Gilmore, PhD, et al. About the Tomatis Method. p 20-24. Toronto, Canada: The Listening Centre Press, 1989.).
If the XY chromosome combination is present, the brain must be changed from that of a female to a male. The change agent is the androgen hormone solution. (Joy, Donald M., PhD. Bonding. p 91. TX:Word Books, 1985.)
Fetus is light sensitive from the 16th week. A direct light held to the mother’s abdomen will startle the fetus and cause it to move away. May cover its eyes in response to light and its ears in response to ultrasound. (Karr-Morse, Robin, and Meredith S. Wiley. Ghosts from the Nursery. p 52. NY:Atlantic Monthly Press, 1997.)