It is important to treat any underlying diseases that cause irregular periods.

The disease had also attacked his spinal cord, leaving him unable to walk, and was causing periods of dementia.

This can cause deep pain on intercourse as well as painful periods.

It's just that with different strains you see them causing different peaking periods.

Being underweight or overweight can cause missed and irregular periods.

Mutations have been identified that cause both long and short periods relative to the wild-type value of 21.5 hours.

This "misplaced" tissue can cause pain, infertility, and very heavy periods.

The following drugs may also cause missed periods:

Sometimes it causes very painful periods; sometimes it's absolutely silent.

Many different problems can cause painful or heavy periods.