Can pregnancy sleep patterns indicate the future onset postpartum depression?

No: Generally, no. Pregnancy does cause sleep related problems, most notably due to discomfort and/or anxiety, and this can increase problems with depression. After delivery, sleep deprivation can add to this. Good mental health includes personal time, exercise and nutrition and deficiencies in any one do increase your risk.

Not necessarily: I need to have more information what you mean. If you aren't able to sleep (insomnia or early morning wakening with difficulty falling back to sleep) that may be a sign that some depression is starting. However, many pregnant women may have difficulty getting comfortable especially as they get larger or have to awaken to use the bathroom. So i would advise you to discuss this with your ob-gyne.