The cramps known as afterbirth pains, or simply after pains, are caused by contractions of your uterus as it returns to its pre-pregnancy size after you have your baby. This process is called involution. These involuntary contractions of the uterus can follow both vaginal birth and caesarean section and usually last for two to three days after childbirth.
Afterbirth pains can often be quite a lot more uncomfortable after a second birth and usually get worse with each successive birth That's because first-time mothers tend to have better uterine muscle tone, which means the uterus can contract and stay contracted, rather than relaxing and contracting intermittently. They are frequently described as intense period pain.