Do Fetuses Poop Inside the Womb?

When a baby is in the mothers womb, and is developed enough, does it produce human waste from the nutrients the mother provides to it? If so, where does it go or how does the body adapt to that?
The following comments answer these questions in detail.


Yes. Just a couple of months into their development, little humans begin peeing freely into the amniotic fluid that surrounds them in the womb. Then, foreshadowing all the gross stuff that babies do once they’re born, they’ll consume that urine as they swallow the amniotic fluid. Every last one of us has spent several months drinking our own pee.

In utero pooping is less common. Fetuses get their nutrients from food that their mothers’ digestive systems have broken down, and the waste from that food stays with mom and is taken care of on her end (Thanks, Mom!). Fetuses do ingest some stuff—mucus, bile, fine fetal hairs called lanugo, cells lining the inside of the womb—that needs to get disposed of, though. All this stuff gets broken down by the fetus’s digestive system and forms a viscous, sticky mass of feces called meconium.

Meconium is almost odorless and mostly sterile. It usually stays in fetuses’ bowels until they’re born, but some kids—around 13 percent—just can’t wait, and let it loose in the womb. This can be a problem, since feces is now floating in the amniotic fluid that the fetus swallows and takes into its lungs, and “meconium-stained amniotic fluid,” as the docs call it, can lead to serious respiratory distress.


Meconium present at birth indicates fetal distress, the baby was stressed by something in the delivery process or shortly before. As has been noted, the stuff is really sticky and if it has been aspirated (inhaled) can lead to breathing difficulties. This can potentially be fatal so meconium at birth is not a good finding.

If a child fails to produce urine due to malformation of the kidneys or urogenital tract (bladder and urethra) a condition called oligohydramnios occurs. Not only do we “drink” our urine as mentioned but we also “breath” it in the womb. Babies inhale and exhale amniotic fluid. If there is insufficient amniotic fluid because baby is not peeing, these breathing movements cannot occur normally and the lungs do not develop normally leading to severe problems at birth which can potentially be fatal. In really severe cases of low amniotic fluid because baby is not making urine something called “Potters sequence” occurs. “Potters” is not someone’s name but comes from the fact that the child looks like they had been trapped in a clay pot. They have abnormal development of the lungs because they have no “breathing” in the womb (the uterus has squeezed them and restricted this), have abnormal development of the joints in the arms, hands, and legs because they could not move (baby could not kick and move in the womb), and have abnormal appearance of their face because it was smushed by the womb. They may not have the normal lines on the palms of their hands because they could not move them. If severe enough oligohydramnios, the child will not survive due to the failure of the lungs to develop normally, the lungs look “solid” and not like “sponges” because they little sacs (alveoli) where oxygen adsorption occurs do not develop. Peeing in the womb is REALLY important!


My baby had meconium in the womb, among a dozen other complications during my wife’s labor. He had a really rough birth, and ended up in the NICU for several days. Seeing sick babies in the NICU, or even reading about it, still gives me anxiety and just makes me feel bad in general. Not the “aww poor baby” bad, but like genuinely upset, and I’m not an emotional person.

Come to find out, from reading about emergency rooms, that people who visit family in the ICU can get PTSD. I visited my brother who was in a coma in an ICU for around a month, he didn’t make it, but I didn’t feel any PTSD from that.
But my infant son being in an NICU with a tube down his throat, and attached to all these devices was really rough. To put you on edge even more their heart monitor is attached the their feet, and if it gets a little loose everything flat lines and an alarm goes off.

But the worst of all was him not breathing when he was born (cord around neck), being blue, and having to be resuscitated. Luckily my wife didn’t see that part because they (obviously) had to immediately take him away.

I don’t care how stoic someone thinks they are seeing your baby in conditions like that is terrifying, and is still the worst experience of my life. My wife was really bad off for a month or so. Luckily we are all doing great now. Our baby boy is 6 and 1/2 months old.


Most fetuses just keep it inside them until they are born, where it is called meconium. If you’ve ever seen a baby shortly after birth, usually their first bowel movements consist of meconium, which is almost totally odorless and a very sticky texture.


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