A Urine Dipstick in Pregnancy
Every finding on this strip means something different in pregnancy, and one of them reverses completely. Bacteria in the urine without symptoms are usually left alone in other adults; in pregnancy they are treated, because untreated they progress to kidney infection far more often and are linked to preterm birth. Protein carries different weight too, since it is one of the features that defines pre-eclampsia.
The pattern on your report
- Protein High Key
- Nitrites High Key
- Glucose High Key
- Leukocyte esterase High Key
Printed as: Glucose in dipstick grade— The kidney's threshold for reabsorbing glucose falls in pregnancy, making this a weak signal in both directions.Leukocyte esterase in dipstick grade— Readily positive from vaginal contamination, so a properly collected midstream sample matters.Nitrites in dipstick grade— Acted on in pregnancy even without symptoms, which is the opposite of the rule elsewhere.Protein in dipstick grade— A rough grade affected by how dilute the sample is. Where it matters, a ratio quantifies it properly.
Why the numbers look like this
Pregnancy changes the urinary tract mechanically and hormonally. Progesterone relaxes the smooth muscle of the ureters, and the growing uterus presses on them, so urine drains more slowly and stagnates. Bacteria that would be flushed out have time to multiply and ascend.
That is why bacteria without symptoms behave differently here. In a non-pregnant adult they usually stay in the bladder and cause nothing; in pregnancy a substantial proportion progress to kidney infection, which is a serious illness for both the pregnancy and the person.
Protein has a different basis. In pre-eclampsia the placental circulation develops abnormally and releases factors that damage blood vessel linings throughout the body, including the kidney's filter, which then leaks protein. Blood pressure rises through the same process.
Glucose appears for a third reason. The kidney's threshold for reabsorbing glucose falls in pregnancy, so glucose can appear in the urine at blood levels that would not produce it otherwise. It is therefore a weak signal, and gestational diabetes is diagnosed on a blood test, not on this.
Not being flagged is not the same as normal
The dipstick reports protein as a rough grade, never a quantity, and it is affected by how dilute the sample is, so a trace in a concentrated first morning sample means less than the same reading in a dilute one. Where protein matters, a laboratory ratio against creatinine quantifies it properly, and pre-eclampsia assessment rests on that. Blood pressure is measured alongside for the same reason: neither finding is interpreted alone.
What else on the report can hide this
Blood pressure belongs with every dipstick from twenty weeks onward. Protein and a raised pressure together define the condition being screened for; either on its own means much less.
Where protein is found, quantifying it with a ratio replaces the grade on the strip, and decisions rest on the ratio.
A urine culture is sent when bacteria are suggested, because treatment is guided by what grows and by what is safe in pregnancy, and because the finding is acted on here rather than ignored.
Symptoms still matter even though the rule about treating changes. Fever, flank pain, vomiting or feeling unwell shift this from a routine finding to a same-day assessment for kidney infection.
Glucose on the strip should prompt the proper test, not reassurance and not alarm. The threshold change in pregnancy makes it a poor guide in both directions, so a glucose tolerance test is what answers the question when risk factors are present.
What usually causes it
Listed from most to least common — not from most to least serious.
- Very common
Bacteria without symptoms
Treated in pregnancy, unlike in other adults, because a substantial proportion progress to kidney infection. A culture guides which antibiotic.
- Very common
A dilute or contaminated sample
Vaginal discharge and a non-midstream sample both produce misleading strips. A repeat, properly collected, resolves many of these.
- Very common
Glucose from the lowered kidney threshold
Expected in pregnancy at blood levels that would not otherwise produce it, which makes the strip a weak guide in both directions.
- Common
Pre-eclampsia
Protein with raised blood pressure after twenty weeks. Neither finding is interpreted alone, which is the reason both are checked at every visit.
- Common
Urinary tract infection with symptoms
Pain, frequency or urgency alongside. Treated promptly, with a culture to guide the choice.
- Common
Gestational diabetes
Diagnosed on a glucose tolerance test, not on the strip. Glucose on the dipstick prompts the proper test where risk factors exist.
- Uncommon
Kidney infection
Fever, flank pain, vomiting or feeling unwell. A serious illness in pregnancy needing same-day assessment.
- Uncommon
Pre-existing kidney disease
Protein present from early pregnancy rather than appearing later, which is what distinguishes it from pre-eclampsia.
- Uncommon
Ketones from vomiting
Common with severe morning sickness. Reflects reduced intake and matters more in pregnancy than outside it.
What is usually checked next
- Blood pressure, measured at the same time Protein and raised blood pressure together define the condition being screened for; either alone means much less.
- A protein-to-creatinine or albumin-to-creatinine ratio Quantifies protein properly, which the strip's grade cannot, and it is what decisions rest on.
- Urine culture Guides which antibiotic, and it matters here because bacteria without symptoms are treated in pregnancy.
- A properly collected midstream repeat Contamination and dilution account for many misleading strips.
- A glucose tolerance test where risk factors are present Answers the gestational diabetes question, which the strip cannot in either direction.
When to seek care sooner
- Emergency Severe headache, visual disturbance, or pain below the ribs on the right
- Emergency Reduced fetal movements
- Emergency Fever with flank pain or vomiting
- Same day Sudden swelling of the face, hands or feet
- Same day Any vaginal bleeding
- Same day Protein on the dipstick with a raised blood pressure
Questions worth bringing to your appointment
- What was my blood pressure at the same visit?
- Should the protein be quantified with a ratio?
- Is a urine culture being sent?
- Does bacteria without symptoms need treating because I am pregnant?
- Do I need a glucose tolerance test?