I have heard lots of people say that "a miscarriage is basically just like a heavy period."
That is simply not true. Don't say it. Don't think it. Don't be fooled by it.
A miscarriage that occurs in the first few weeks of pregnancy may have the physical characteristics of a menstrual period: several days of cramping and bleeding. It might even seem like a 'normal' period to some women. A woman who didn't know that she was pregnant might even mistake a miscarriage for a period. All the same, if the woman knew she was pregnant, then even these early and physically easy miscarriages may carry an emotional toll that a regular menstrual period does not.
Some mothers really do have a miscarriage that is just like a period. For whatever reason, they do not grieve, or do not grieve very much. If you are one of those mothers you should not feel guilty about it, nor feel that your miscarriage was any less than someone elses. However this experience seems to happen in the minority of cases.
I miscarried this baby at 5 weeks gestation, and physically the process was like a textbook menstrual period. It was not the same as my normal periods which was one of the reasons I knew it was a miscarriage, but to another woman it could have been completely normal. However, if you read what I wrote at the time, it is obvious that my emotional state was not "just like a period" at all. I was grieving.
Somewhere between 6-10 weeks another change occurs. It varies from woman to woman and even from pregnancy to pregnancy, but somewhere in there the baby gets large enough that the physical process of miscarriage stops being like a period, and starts being more like labor. The uterus must contract and the cervix must open in order to expel the baby and placenta and other "products of conception."
When I experienced my first miscarriage I was 14 1/2 weeks along. I labored on and off for almost a full day, but had no idea what was going on. I thought I had intestinal gas, but hindsight tells me that it was actually labor contractions. I knew that a full-term stillborn baby would require labor and delivery, but I had never guessed that a baby only 4 inches long might also require labor.
It is my understanding (and my experience) that the labor of miscarriage is often shorter than a full-term labor would be, because a smaller baby can be delivered with less cervical dilation and pushing. Some women feel that it is something like the "first half" of labor. Others feel that it is very comparable to laboring with a full-term child.
This is one of those big unspoken secrets: many miscarriages are not like a heavy period, they are the labor and birthing of a baby.