Left Flank Pain in Pregnancy: What to Know

As pregnancy progresses, posture, ligaments, and pressure from the growing uterus can cause back or side discomfort. Flank pain can also occur with a kidney stone or urinary infection. A kidney infection commonly presents with flank pain and fever and may cause chills, nausea, or painful urination. Pregnancy can make urinary infections more significant, and symptoms should be reported rather than watched at home. Pain may also be related to contractions or another pregnancy concern, especially when it comes with pelvic pressure, fluid leakage, bleeding, or a change in fetal movement later in pregnancy.

Contact your maternity team, midwife, or clinician for advice about new or persistent flank pain. Tell them how far along the pregnancy is, whether you have fever or urinary changes, and whether the pain is constant, wave-like, or linked to movement. Rest in a comfortable position and drink normally unless your care team has given different instructions. Use only medicines approved for you in pregnancy; avoid borrowing antibiotics or taking a new pain medicine without checking first. Urine testing is often useful when infection is possible.

Seek urgent maternity or emergency care for severe or worsening pain, fever with chills, repeated vomiting, vaginal bleeding, fluid leakage, regular tightening, fainting, confusion, inability to pass urine, or reduced fetal movement when movements are expected. Do not wait for a routine appointment if you feel seriously unwell.

Could this be a urinary infection, stone, muscle strain, or pregnancy-related pain? Do I need a urine test or pregnancy-safe imaging? Which pain relief is suitable? What symptoms should send me directly to maternity triage?