Bladder irritability causing increased frequency of urination is common in the later stages of pregnancy where the pressure of the foetal head on the bladder both reduces its capacity and increases its readiness to contract, producing the symptoms of urgency (when you got to go you got to go). Increase production of urine in the early stages of pregnancy is due to increased production by the kidneys in response to circulating hormones. It is thought that this is due to the need to excrete the metabolites produced by the intense activity occurring during embryonic life, when all the major organ systems are being formed. While frequency and urgency are unpleasant they are usually bearable; if there is associated urinary tract infection there will also be pain. Painful urinary frequency in pregnancy (as at all other times) needs investigation.