I had spotting around that time when I was doing too much: lifting things heavier than a gallon of milk, wearing myself out cleaning or doing yard work or taking the kids places,...taking really long, really hot showers/baths...not getting enough water, etc.
I think I did have some spotting after sex once or twice...but it doesn't stand out in my memory.
When I had my miscarriage, I didn't have spotting in the days before the cramping started. I had regular cramps which I recognized as being in labor. Also I started bleeding but it was red not pink. I drank lots of water and went to bed - hoping the labor cramps would go away. After 20 minutes of these regular cramps, I knew it was over and asked my husband to take me to the hospital.
I also had about half a period around 7 weeks when I had my twins. I've heard that this is really common.
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so, cut back on your activities. Drink more water. Pay attention to your body. Call your OB. Your doctor or maybe even a nurse should be able to answer this question over the phone - tell you what to watch for, set your mind at ease, etc..