Weeks 15 & 16

Substantial neuroscience research concludes that the fetus can feel pain by 15 weeks. One can examine the development of pain receptors, pain neurotransmitters, and brain structures supporting the awareness of pain. While touch receptors cover almost all of the body, pain receptors develop later than regular touch receptors. Pain receptors develop from 10 to 17 weeks, starting in the hands and the area around the mouth.⁵ Two neurotransmitters specific to pain processing, substance P and enkephalins, have already appeared at 10 to 12 weeks and 12 to 14 weeks, respectively. Furthermore, nerves connecting the primitive pain receptors with the spinal cord and thalamus can be observed as early as 15 weeks.⁶ While the cortex may not be fully developed, a number of brain structures that process pain activity including the brainstem, insula, and thalamus, are sufficiently mature to process pain at 15 weeks.⁷ Taken together, there is considerable evidence that a fetus can now feel pain.

Furthermore, researchers who have devoted their careers to the neuroscience of pain have concluded that fetal pain is possible from a very early age. Two medical professionals, one pro-choice and one pro-life came to the following conclusion:

“Overall, the evidence, and a balanced reading of that evidence, points towards an immediate and unreflective pain experience mediated by the developing function of the nervous system from as early as 12 weeks.⁹”

 

Similarly, European neurologists and embryologists came to a similar conclusion in 2016:

“…the fetus is exposed to rudimentary painful stimuli starting from the 15th gestation week and … it is extremely sensitive to painful stimuli.¹⁰“

Many sensory systems start processing basic information in weeks 15 and 16. The olfactory bulb, which processes smells, develops its layered structure at 14 weeks.¹⁶ Tastebuds start clustering in functional taste pores and connecting to cranial nerves at 14 to 15 weeks, making it likely that the fetus tastes the amniotic fluid.¹⁷ In fact, by 15 to 16 weeks, the fetus will swallow more amniotic fluid if the amniotic fluid tastes sweet, and less if it tastes bitter.¹⁸ Each sensory system is at least partially developed by 15 weeks.

Every body system continues advancing each week. By week 15, eyebrows have formed.¹⁹  The stomach lining secretes digestive enzymes into swallowed amniotic fluid.²⁰

In bone development, the structures destined to become bone often start as cartilage. As development continues, the cartilage is slowly replaced by bone cells. In a single long bone, the middle of the bone starts to harden first, and the ends keep growing longer and longer as cartilage. This cartilage, too, is later replaced by bone. By 15 weeks, if a doctor took an X-ray this week, the fetus’s skeleton would be visible.²¹