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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 17 & 18

Breathing, crying, and the rooting reflex

Human Prenatal Age
  • PCW 17&18
    i
    Post-Conception Weeks
  • 5 Months Pregnant
  • Gestational Weeks 19&20
Highlights

  • Multiple research studies have shown that the fetus responds to painful stimuli with a stress response that includes recoiling and increased circulating stress hormones separate from stress hormones in the mother’s bloodstream.1

  • The skin has developed sweat glands.2

  • By 17 weeks after conception, the fetal heart has beat over 20 million times.3

  • The fetal heart pumps about 55 quarts of blood each day.4

The fetus practices lots of activities he will use outside the womb. For example, by 18 weeks after conception, the preborn baby’s vocal cords move in a similar pattern to that seen during crying after birth.5 The fetus also practices breathing.6

Helpful reflexes

Although the fetus used to move away when something touched his face, the fetus now rotates his head towards things that touch his face while simultaneously closing his mouth.7 These movements mark the start of the rooting reflex, which helps a newborn find his mother’s nipple during breastfeeding.

7
milliliters
Around 20 weeks gestation, the fetus drinks 2-7 mL of amniotic fluid each day.8 For comparison, the fetus drinks 500-1000 mL of amniotic fluid each day in the last month of pregnancy.9 Similarly, about a week after birth a newborn drinks about 500 mL of breastmilk or formula per day.10
This baby is already practicing breathing, crying and breastfeeding to prepare for his birth. (Image Credit: Priests for Life)
Visual development

Although the eyelids are fused shut between 7 and 24 weeks gestation, the eyes keep developing. The back of the eye, called the retina, which converts light into neural signals, now has discrete layers, each with a different main type of cell.11

In animals, waves of spontaneous electrical activity cross the retinas. This allows the retinal cells to properly connect to the visual cortex in the brain, and to organize inputs from the right and left eyes.12 Although these spontaneous retinal waves have never been directly measured from the human fetus, they likely begin around this age.

Dive Deeper
Fetal Surgery: Treating Babies Before They are Born
Some babies can receive life-saving treatment while still inside the womb—long before they are even born...
Read More
Perinatal Hospice
Perinatal hospice care provides comprehensive prenatal, perinatal, and postnatal medical care...
Read More
Back to The Voyage of Life
Sources
  1. X Giannakoulopoulos et al., “Fetal Plasma Cortisol and β-Endorphin Response to Intrauterine Needling,” The Lancet, Originally published as Volume 2, Issue 8915, 344, no. 8915 (July 9, 1994): 77–81, https://doi.org/10.1016/S0140-6736(94)91279-3; Giannakoulopoulos et al., “Human Fetal and Maternal Noradrenaline Responses to Invasive Procedures”; Rachel Gitau et al., “Fetal Hypothalamic-Pituitary-Adrenal Stress Responses to Invasive Procedures Are Independent of Maternal Responses,” The Journal of Clinical Endocrinology & Metabolism 86, no. 1 (January 1, 2001): 104–9, https://doi.org/10.1210/jcem.86.1.7090; Vivette Glover, “The Fetus May Feel Pain from 20 Weeks,” Conscience XXV, no. 3 (2005), https://search.proquest.com/openview/fc0b3f03afddeb32f1658bdfbe66605f/1?pq-origsite=gscholar&cbl=26891; Amr Morsi, Donald DeFranco, and Selma F. Witchel, “The Hypothalamic-Pituitary-Adrenal Axis and the Fetus,” Hormone Research in Paediatrics 89, no. 5 (2018): 380–87, https://doi.org/10.1159/000488106.
  2. Pringle, K. C. “A Reassessment of Pregnancy Staging.” Fetal Diagnosis and Therapy 3, no. 3 (1988): 173–84. https://doi.org/10.1159/000263352.
  3. EHD: Appendix. Appendix
  4. Molina, F. S., C. Faro, A. Sotiriadis, T. Dagklis, and K. H. Nicolaides. “Heart Stroke Volume and Cardiac Output by Four-Dimensional Ultrasound in Normal Fetuses.” Ultrasound in Obstetrics & Gynecology: The Official Journal of the International Society of Ultrasound in Obstetrics and Gynecology 32, no. 2 (August 2008): 181–87. https://doi.org/10.1002/uog.5374.
  5. López Ramón y Cajal, C. “Description of Human Fetal Laryngeal Functions: Phonation.” Early Human Development 45, no. 1–2 (July 5, 1996): 63–72. https://doi.org/10.1016/0378-3782(95)01721-6.
  6. Hepper, P.G. “Unravelling Our Beginnings | The Psychologist,” 2005. https://thepsychologist.bps.org.uk/volume-18/edition-8/unravelling-our-beginnings.”
  7. Humphrey, Tryphena. “Some Correlations between the Appearance of Human Fetal Reflexes and the Development of the Nervous System.” In Progress in Brain Research, edited by Dominick P. Purpura and J. P. Schadé, 4:93–135. Growth and Maturation of the Brain. Elsevier, 1964. https://doi.org/10.1016/S0079-6123(08)61273-X.
  8. Grand, Richard J., John B. Watkins, and Frank M. Torti. “Development of the Human Gastrointestinal Tract: A Review.” Gastroenterology 70, no. 5 (May 1, 1976): 790–810. https://doi.org/10.1016/S0016-5085(76)80277-6.
  9. Grand, Richard J., John B. Watkins, and Frank M. Torti. “Development of the Human Gastrointestinal Tract: A Review.” Gastroenterology 70, no. 5 (May 1, 1976): 790–810. https://doi.org/10.1016/S0016-5085(76)80277-6
  10. John P Cloherty, Eric C Eichenwald, and Ann R Stark, Manual of Neonatal Care, 8th ed. (Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins, 2017).
  11. Hendrickson, Anita, Keely Bumsted-O’Brien, Riccardo Natoli, Visvanathan Ramamurthy, Daniel Possin, and Jan Provis. “Rod Photoreceptor Differentiation in Fetal and Infant Human Retina.” Experimental Eye Research 87, no. 5 (November 2008): 415–26. https://doi.org/10.1016/j.exer.2008.07.016.
  12. C J Shatz, “Emergence of Order in Visual System Development.,” Proceedings of the National Academy of Sciences of the United States of America 93, no. 2 (1996): 602–8, https://doi.org/10.1073/pnas.93.2.602.
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 May 20, 2023