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The Endowment for Human Development
The Endowment for Human Development
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Multilingual Illustrated DVD [Tutorial]

The Biology of Prenatal Development

Introducing the Multilingual Illustrated DVD
Explore the fascinating imagery and facts presented in The Biology of Prenatal Development at your own pace. Each clip from the program is accompanied by its corresponding written script. Select Play Movie to watch any clip. Select See Snapshots to view high resolution images. See the program script and subtitles in 88 languages by using the Choose Language drop-down menu and clicking Refresh. Subtitles are displayed in your chosen language and may be turned on and off by clicking the button found in the lower right corner of the movie player. A "full screen" option is also available by clicking the button.

National Geographic Society This program is distributed in the U.S. and Canada by National Geographic and EHD. [learn more]

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Chapter 43   6 to 7 Months (24 to 28 Weeks): Blink-Startle; Pupils Respond to Light; Smell and Taste

By 24 weeks the eyelids reopen and the fetus exhibits a blink-startle response. This reaction to sudden, loud noises typically develops earlier in the female fetus.

Several investigators report exposure to loud noise may adversely affect fetal health. Immediate consequences include prolonged increased heart rate, excessive fetal swallowing, and abrupt behavioral changes. Possible long-term consequences include hearing loss.

The fetal respiratory rate can rise as high as 44 inhalation-exhalation cycles per minute.

During the third trimester of pregnancy, rapid brain growth consumes more than 50% of the energy used by the fetus. Brain weight increases between 400 and 500%.

By 26 weeks the eyes produce tears.

The pupils respond to light as early as 27 weeks. This response regulates the amount of light reaching the retina throughout life.

All components required for a functioning sense of smell are operational. Studies of premature babies reveal the ability to detect odors as early as 26 weeks after fertilization.

Placing a sweet substance in the amniotic fluid increases the rate of fetal swallowing. In contrast, decreased fetal swallowing follows the introduction of a bitter substance. Altered facial expressions often follow.

Through a series of step-like leg motions similar to walking, the fetus performs somersaults.

The fetus appears less wrinkled as additional fat deposits form beneath the skin. Fat plays a vital role in maintaining body temperature and storing energy after birth.

Chapter 44   7 to 8 Months (28 to 32 Weeks): Sound Discrimination, Behavioral States

By 28 weeks the fetus can distinguish between high- and low-pitched sounds.

By 30 weeks, breathing movements are more common and occur 30 to 40% of the time in an average fetus.

During the last 4 months of pregnancy, the fetus displays periods of coordinated activity punctuated by periods of rest. These behavioral states reflect the ever-increasing complexity of the central nervous system.

Chapter 45   8 to 9 Months (32 to 36 Weeks): Alveoli Formation, Firm Grasp, Taste Preferences

By approximately 32 weeks, true alveoli, or air "pocket" cells, begin developing in the lungs. They will continue to form until 8 years after birth.

At 35 weeks the fetus has a firm hand grasp.

Fetal exposure to various substances appears to affect flavor preferences after birth. For instance, fetuses whose mothers consumed anise, a substance which gives licorice its taste, showed a preference for anise after birth. Newborns without fetal exposure disliked anise.

Chapter 46   9 Months to Birth (36 Weeks through Birth)

The fetus initiates labor by releasing large amounts of a hormone called estrogen and thus begins the transition from fetus to newborn.

Labor is marked by powerful contractions of the uterus, resulting in childbirth.

From fertilization to birth and beyond, human development is dynamic, continuous, and complex. New discoveries about this fascinating process increasingly show the vital impact of fetal development on lifelong health.

As our understanding of early human development advances, so too will our ability to enhance health - both before and after birth.