Question: what cause change in menstruation when one changes her environment?

Under which circumstances one is able to do sex without ejaculating? (2 comments)

why do black holes not allow light through them (2 comments)

What causes Rheumatic fever (2 comments)

can you be my mentor (5 comments)

i would like to be a paedetrician which sciences am I supposed 2 take? What advantages and disadvantages are associated (1 comment)