# Is the skin/placenta thin enough to allow any light into the human womb during pregnancy? **URL:** \ **Category:** Factual Questions\ **Created:** [February 18, 2017, 3:46pm UTC](https://boards.straightdope.com/t/is-the-skin-placenta-thin-enough-to-allow-any-light-into-the-human-womb-during-pregnancy/780148 "2017-02-18T15:46:41Z")\ **Posts on this page:** 6\ **Page:** 2
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [February 20, 2017, 10:15pm UTC](https://boards.straightdope.com/t/is-the-skin-placenta-thin-enough-to-allow-any-light-into-the-human-womb-during-pregnancy/780148/21 "2017-02-20T22:15:26Z")
> [@Blue\_Blistering\_Barnacle](#): > > Lastly, when I was a kid we would shine regular flashlights through our hands to see the creepy dim red glow all the time. In addition, the fetus will be in an order of magnitude greater darkness than that unless you’re shining the flashlight in a closet or in an overcast moonless night, so their eyes will pick up much fainter things. If you _were_ in a closet or an overcast moonless night, I imagine the light shining through your hand would seem quite bright. ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [February 20, 2017, 10:25pm UTC](https://boards.straightdope.com/t/is-the-skin-placenta-thin-enough-to-allow-any-light-into-the-human-womb-during-pregnancy/780148/22 "2017-02-20T22:25:40Z")
How do you make a blonde’s eyes light up? Shine a flashlight in her ear! ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [February 20, 2017, 11:38pm UTC](https://boards.straightdope.com/t/is-the-skin-placenta-thin-enough-to-allow-any-light-into-the-human-womb-during-pregnancy/780148/23 "2017-02-20T23:38:35Z")
> [@Waxwinged](#): > > … Okay, I expected better from the Straight dope… ☹ - hides head in shame \* ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [February 20, 2017, 11:41pm UTC](https://boards.straightdope.com/t/is-the-skin-placenta-thin-enough-to-allow-any-light-into-the-human-womb-during-pregnancy/780148/24 "2017-02-20T23:41:35Z")
> [@Der\_Trihs](#): > > It would have to be very bright; the [eyes of infants](https://en.wikipedia.org/wiki/Infant_visual_development) are much worse at seeing in dim light than an adult’s. > > > [@](#): > > > > The threshold for light sensitivity is much higher in infants compared to adults. From birth, the pupils of an infant remain constricted to limit the amount of entering light. In regards to pupil dimensions, newborn’s pupil grow from approximately 2.2 mm to an adult length of 3.3 mm.[2] A one-month-old infant can detect light thresholds only when it is approximately 50 times greater than that of an adult. Huh. But don’t they say “no camera flashes” of a newborn? I thought that that was [a] reason for not casting them, so to speak, in Hollywood films. Or is that an old medical opinion? ---
**Author:** ![Waxwinged](https://avatars.discourse-cdn.com/v4/letter/w/c2a13f/32.png) [@Waxwinged](https://boards.straightdope.com/u/Waxwinged)\ **Post date:** [February 21, 2017, 7:35pm UTC](https://boards.straightdope.com/t/is-the-skin-placenta-thin-enough-to-allow-any-light-into-the-human-womb-during-pregnancy/780148/25 "2017-02-21T19:35:35Z")
> [@Weisshund](#): > > Aside from stucking a Q-beam to the womans stomach, which might show as a red glow inside, you are not getting normal light past 7 layers of skin, fat, muscle, uterus, fluid, placenta etc. > > it’s quite dark in there. > . Thank you! ---
**Author:** ![Oukile](https://avatars.discourse-cdn.com/v4/letter/o/13edae/32.png) [@Oukile](https://boards.straightdope.com/u/Oukile)\ **Post date:** [February 21, 2017, 9:07pm UTC](https://boards.straightdope.com/t/is-the-skin-placenta-thin-enough-to-allow-any-light-into-the-human-womb-during-pregnancy/780148/26 "2017-02-21T21:07:09Z")
> [@Blue\_Blistering\_Barnacle](#): > > I have read (not recently at all) that enough light can penetrate the scalp and skull to faintly illuminate the pineal gland. This is difficult to credit[…] Well I can credit that. A while ago, I head a conference by a researcher developing transcranial optical imaging techniques. He mentionned that if you stand in the sun, there will be enough light in your cranium to read a newspaper (I don’t know about the pineal gland though). [Previous page](https://boards.straightdope.com/t/is-the-skin-placenta-thin-enough-to-allow-any-light-into-the-human-womb-during-pregnancy/780148.md?page=1)