My seven year old daughter has been very curious about how the birthing process works. I found a good collection of educational videos online about mammalian pregnancies including humans, but none of them explain in a normal pregnancy how the placenta detaches.
Does it detach when the uterus contracts after the baby is delivered? Are hormones released? All of the above?
In: Biology
Your call on telling a 7-year old this.
After delivery, contractions continue. Without the fluid (and baby) to fill the womb and push back on the contractions they hurt less and shrink the womb more. The placenta isn’t shrinkable, or solid enough to resist the contractions (these muscles are strong). As a result, it is sheared off from the uterine wall and ultimately expelled/delivered.
What they said. Also, this is much worse in humans than in most other mammals die to the degree of invasion of the uterus by the placenta. Most other mammals have much less invasive placentas that tear off more easily. Human babies (and rodents like Guinean pigs interestingly) require so many nutrients that the placental cells invade deep into the uterus and wrap around the mothers blood vessels. This makes the separation more painful and bleed more.
Latest Answers