Toilet time again! Hormonal changes and a growing uterus place pressure on the bladder, which leads to many more bathroom breaks. So too does an increase in blood volume, which puts your kidneys into overdrive [source: Women's Healthcare Topics] Frequent urination is most noticeable during the first and third trimesters of pregnancy, though some women may continue making frequent trips to the bathroom throughout he entire pregnancy.
While you may want to limit your intake of liquids during this time to avoid urinating so frequently, please don't. It's important to drink lots of water throughout your pregnancy to stay hydrated, although you may want to ingest the bulk of your daily fluid intake during the daytime to limit nighttime bathroom trips.