Ordinarily, urine has little to no odor. Certain medical conditions, however, may cause your urine to become strong- or foul-smelling or may affect the odor of your vulva and vaginal discharge, so that you think your urine smells bad. A strong urine odor in females can be harmless or the sign of a serious problem.
Urine that is dark and smells strongly like ammonia may be a sign of dehydration, when your body doesn't have enough water. According to BabiesOnline.com, pregnant women are at risk for dehydration, especially in early pregnancy, because they lose fluid when they vomit due to morning sickness and may have trouble keeping food or liquid down. It can cause deformities (in early pregnancy) or preterm labor (in late pregnancy). Pregnant or not, you should pay attention to your urine and other symptoms of dehydration, such as headache and dizziness, and drink plenty of water to avoid it.
Bacteria in the vagina, such as trichomoniasis and gardnerella, can cause bad odors in the vulva, making you think that your urine smells bad, advises Columbia's health advice columnist Alice. In addition, the Mayo Clinic warns that women are at a greater risk than men for developing urinary tract infections, which can cause a foul odor in the urine, as well as burning during urination, fever and back pain. Doctors can treat both types of infection with antibiotics. An untreated urinary tract infection can cause kidney damage and, in pregnant women, premature births, according to the Mayo Clinic.
A fistula is an abnormal connection between organs in the body. According to the Mayo Clinic, childbirth, inflammatory bowel disease and surgery are some of the causes for a fistula between your bowel and vagina (rectovaginal fistula), which may cause strong-smelling vaginal discharge (again, mistaken for strong-smelling urine) and urinary tract infections, which can cause strong-smelling urine. Vesicoenteric fistulae, which occur between the bowel and bladder, can also cause bad urine smells, writes Dr. Joseph Basler on eMedicine.com.