There are several reasons why you may develop constipation including: not eating enough fibre, not drinking enough fluid, certain medicines e. g. antidepressants, calcium or iron supplements or painkillers(e. g. codeine or morphine), being inactive, fear about using the toilet e. g. because you worry people can see or hear you, stress or depression or even pregnancy, around 4 in 10 women who are pregnant have constipation.
Attribution: BUPA