I imagine you are reading this because you or someone close to you is pregnant, in which case you are probably not going to be weirded-out by descriptions of basic biological processes and structures. If you are, I would recommend care with choice of your reading matter!
Well, perhaps it is no less miraculous, but a 'miracle' conjures up an image of something that, well, just happens; and perhaps misses how much bloody* effort, discomfort, and emotion go into the whole affair.
An inflammatory condition of the lining of the womb, usually due to infection. It is more likely with incomplete delivery of the placenta or other retained products of conception (RPOC) such as membranes or other tissue from the foetus.
This is when the uterus, or womb, gets turned partially or completely inside out, often because the placenta has remained attached and pulls on it. This is rare, but can be associated with severe haemorrhaging (bleeding) and shock. Again, it is extremely unlikely that you will have been allowed to go home if there is a chance this happened during your labour.
This was the most Safe For Life image I could find! Google 'uterine inversion' at your peril if you have a weak stomach!
Unrecognised visceral (organ) injury
A lot of force goes into getting your baby from inside the womb to the outside world [through a relatively small opening]. A rare complication of giving birth is injuring one or more of the internal organs in your abdominal or pelvic cavity.
A more common, and more benign, related source of pain during or after childbirth is urinary retention, that is, a full bladder.
It is possible to graze or tear the lining of the vagina, which is about as painful as it sounds. It is also common to stretch or even tear the perineum, the area between your vagina and rectum. This postpartum pain may be exacerbated if your doctor performed an episiotomy, where they make a small cut in this area to help the baby out.
Again, a certain amount of pain in these areas is normal, and if you think about what just went on there, even likely, but the amount (and colour) of any bleeding should be monitored.
Having pushed the baby out, the uterus is still not back to its pre-pregnancy size. Afterpains for a few days following delivery are normal, and may feel like amped-up versions of the cramps you get with your period. If you breastfeed, you may notice these pains more then; as breastfeeding releases hormones that cause the uterus to contract.
And then there is what I call the Feeling Like You've Been Hit By A Truck Syndrome.
Even with a fairly short, uncomplicated labour, you will be sore in places you didn't even know existed.
Your abdominal muscles were stretched further than they have ever known, just from being pregnant. They then had to contract hard enough to push a moving, struggling being through a canal that is much too small for it.
Sore, leaky breasts as your milk comes in (and the pain of blocked ducts if you are unlucky enough to experience those), night sweats as your body expels the retained fluid from pregnancy, headaches (which may be from the hormone levels changing) constipation and hair loss are all likely over the coming days and weeks.