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Charlotte Lozier Institute

Phone: 202-223-8073
Fax: 571-312-0544

2776 S. Arlington Mill Dr.
#803
Arlington, VA 22206

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Charlotte Lozier Institute

Phone: 202-223-8073
Fax: 571-312-0544

2776 S. Arlington Mill Dr.
#803
Arlington, VA 22206

The
Voyage of Life
Preparing for Pregnancy
Week 0 to 1
Week 1 to 2
Week 2 to 3
Week 3 to 4
Week 4 to 5
Week 5 to 6
Week 6 to 7
Week 7 to 8
Week 8 to 9
Week 9 to 10
Week 10 to 11
Week 11 to 12
Weeks 13 & 14
Weeks 15 & 16
Weeks 17 & 18
Weeks 19 & 20
Month 6 to 7
Month 7 to 8
Month 8 to 9
Month 9 to Birth

Weeks 15 & 16

Stress response and pain

Human Prenatal Age
  • PCW 15&16
    i
    Post-Conception Weeks
  • 5 Months Pregnant
  • Gestational Weeks 17&18
Highlights

  • The fetus responds to a needle entering his hepatic vein with a stress response that includes recoiling and increasing circulating stress hormones in his bloodstream separate from any stress hormones in the mother’s bloodstream.1

  • The fetus begins storing energy as body fat. Fat deposits make the baby’s cheeks chubby.2

  • The corpus callosum, which connects the right and left sides of the brain, begins developing.3

  • About 15 weeks after conception, fetal blood cells start forming in the bone marrow.4 Blood cells will form in the bone marrow for the rest of the baby’s life.

Although the baby started moving 6 weeks after conception, the fetus has finally become big enough and strong enough for the mother to feel. A pregnant mother can usually feel her unborn child moving around 16 weeks after conception if she has had a previous child, and 18 weeks if she has not. This is also known as quickening.5

In the fifteenth and sixteenth week after conception, the mother may feel her unborn child moving. (Image Credit: Priests for Life)

These weeks, the airways in the lungs keep developing. Cilia, which started to grow 13 weeks after conception, are now developing at a rapid pace.6 Cilia are tiny hair-like projections protruding from the cells that line the airway. Cilia catch debris and mucus and sweep it towards the throat, helping prevent infections in the lungs. The mature cells that line the airway will have about 200 cilia each.7

Some experts believe that the formation of airways in the lungs finishes about 16 weeks after conception,8 although the sites of gas exchange in the lungs, called alveoli, still need to develop and mature.

Furthermore, sporadic eye movements start between 14 and 16 weeks after conception.9 These have been detected using ultrasound.

Finally, stress and pain responses in the unborn have been recorded from fetuses as young as 16 weeks after conception. When doctors used a needle to draw blood from a vein near the fetus’s liver, the fetus responded by recoiling. Furthermore, large increases in stress hormones were observed in the fetus’s blood, but not the mother’s blood, showing that the fetus’s stress response was separate from the mother’s.10

Dive Deeper
Prenatal Stress and Pain
Touch receptors first develop around the mouth around 5 1/2 weeks after conception...
Read More
The Science of Fetal Pain
The old, uninformed notions that unborn and newborn babies cannot feel pain are refuted by a growing body of scientific evidence.
Read More
Back to The Voyage of Life
Sources
  1. Xenophon Giannakoulopoulos et al., “Human Fetal and Maternal Noradrenaline Responses to Invasive Procedures,” Pediatric Research 45, no. 4 (April 1999): 494–99, https://doi.org/10.1203/00006450-199904010-00007.
  2. C. M. Poissonnet, A. R. Burdi, and S. M. Garn, “The Chronology of Adipose Tissue Appearance and Distribution in the Human Fetus,” Early Human Development 10, no. 1–2 (September 1984): 1–11, https://doi.org/10.1016/0378-3782(84)90106-3.
  3. Keunen, Kristin, Serena J. Counsell, and Manon J. N. L. Benders. “The Emergence of Functional Architecture during Early Brain Development.” NeuroImage, Functional Architecture of the Brain, 160 (October 15, 2017): 2–14. https://doi.org/10.1016/j.neuroimage.2017.01.047.
  4. K. C. Pringle, “A Reassessment of Pregnancy Staging,” Fetal Diagnosis and Therapy 3, no. 3 (1988): 173–84, https://doi.org/10.1159/000263352.
  5. Moore, Keith, TVN Persaud, and Mark G. Torchia. The Developing Human, Clinically Oriented Embryology. 10th ed. Philadelphia: Elsevier, 2016.
  6. J. W. DiFiore and J. M. Wilson, “Lung Development,” Seminars in Pediatric Surgery 3, no. 4 (November 1994): 221–32.
  7. Guyton, AC, and JE Hall. Textbook of Medical Physiology. 10th ed. Philadelphia: W.B. Saunders, 2000.
  8. J. W. DiFiore and J. M. Wilson, “Lung Development,” Seminars in Pediatric Surgery 3, no. 4 (November 1994): 221–32.
  9. Salihagić Kadić, Aida, and Maja Predojević. “Fetal Neurophysiology According to Gestational Age.” Seminars in Fetal and Neonatal Medicine, Fetal Neurology: Volume 1, 17, no. 5 (October 1, 2012): 256–60. https://doi.org/10.1016/j.siny.2012.05.007.
  10. Xenophon Giannakoulopoulos et al., “Human Fetal and Maternal Noradrenaline Responses to Invasive Procedures,” Pediatric Research 45, no. 4 (April 1999): 494–99, https://doi.org/10.1203/00006450-199904010-00007.
See Full Bibliography

All images and illustrations on The Voyage of Life were reviewed by credentialed scientists for accuracy.

Medical art animation was used to provide a schematic representation of fetal development, with some features, including timing, not to scale. The animation was chosen as an ethically uncompromised guide to fetal development. There are many real human images at each developmental age showing the most accurate fetal forms throughout development. A concerted effort was made to use images and material in which the human embryo or fetus did not undergo any known harm.

Page last updated on March 4, 2023