Protein in Your Urine in Pregnancy

The symptoms that cannot wait for a test

If protein has been found in your urine, or you are waiting on a result, these symptoms mean contacting your midwife or maternity unit immediately rather than waiting for the next appointment:

• a severe headache, particularly one that painkillers do not shift
• vision problems — blurring, or flashing lights before your eyes
• severe pain just below your ribs, classically on the right
• a sudden increase in swelling in your face, hands, legs or feet
• feeling sick and being sick
• heartburn that does not go away when you take antacid medicine
• feeling very unwell

The NHS lists these as the symptoms of pre-eclampsia that need an immediate call. RCOG's patient information gives the same cluster. The NHS red-flag page adds that sudden vision problems and sudden swelling both "need to be checked immediately".

Call 999 if you have a fit (seizure), because that is eclampsia and is an emergency.

Why your urine is tested every single time

Protein in urine, called proteinuria, is one of the two core findings that define pre-eclampsia. The other is raised blood pressure. That is the whole reason the two things that happen at every antenatal appointment are a blood pressure cuff and a urine pot.

NICE's guideline on hypertension in pregnancy (NG133) builds its assessment and monitoring recommendations around exactly this pairing, which is why a raised reading on one usually triggers a closer look at the other.

The NHS makes the point that drives the whole system: pre-eclampsia often causes no symptoms in its early stages, and most cases are picked up during routine antenatal checks rather than because someone felt unwell. The test is not looking for confirmation of how you feel. It is looking for something before you feel it.

How the test works

The first-line test is a dipstick dipped in a fresh sample, read either by eye or by an automated reader. It reports protein as a trace, or as one plus, two plus and so on. It is quick, cheap and deliberately over-sensitive, which is the source of most of the anxiety around it: it flags far more often than pre-eclampsia occurs.

A positive dipstick therefore does not mean pre-eclampsia. It means a second, more precise test is needed. That is usually a laboratory measurement on a single sample expressing protein against creatinine, which removes the effect of how dilute the sample was.

The other reasons a dipstick shows protein

• A urine infection. Common in pregnancy and a frequent cause of a positive dip. This is why a sample is often sent for culture at the same time.
• Contamination. Vaginal discharge in the sample is a genuine and common cause, which is why you may be asked to give a clean mid-stream sample.
• A concentrated sample. Dehydration concentrates everything, including protein.
• Pre-existing kidney disease. Uncommon, but the reason protein at a booking appointment is treated differently from protein at 32 weeks.

What happens if protein is confirmed

The pathway is predictable, and knowing it removes a lot of the fear:

• Your blood pressure is measured, usually more than once.
• A quantified urine test is sent.
• Blood tests are taken to look at kidney function, liver function and platelets.
• Your baby is assessed — movements, heartbeat, growth measurement, and often a scan.
• You are asked about headache, vision, upper abdominal pain and swelling.

Where pre-eclampsia is diagnosed, NICE's guideline is built around monitoring, blood pressure treatment and planning the timing of birth. The NHS is clear that the only cure is the baby being born, and that until then the condition is managed with monitoring and medication, usually with admission to hospital if it is significant.

Where it is not confirmed, you are likely to be asked to come back for repeat checks rather than simply discharged, because pre-eclampsia can develop over days.

Why "trace" usually means nothing

A trace result is the lowest reading a dipstick reports and is extremely common, particularly in a concentrated first-thing sample. On its own, with a normal blood pressure and no symptoms, it is generally repeated rather than investigated. One plus or more, or any level of protein alongside a raised blood pressure, is what changes the plan. If nobody explains which of those applies to you, it is a reasonable question to ask before you leave the room.

Who is watched more closely

ACOG and the NHS both publish risk factors that raise the level of monitoring: a first pregnancy, pre-eclampsia in a previous pregnancy, a gap of ten years or more since your last pregnancy, a family history of the condition, being 40 or over, a high BMI, a multiple pregnancy, and pre-existing high blood pressure, kidney disease, diabetes or an autoimmune condition such as lupus.

If you carry these, you may be offered low-dose aspirin from early in the second trimester, more frequent appointments, and additional growth scans. That is preventive, not a sign anything has gone wrong.

What you can do

Not much, and that is honest rather than defeatist. You cannot lower urinary protein through diet or fluid. What you can do is:

• Attend every appointment, including the ones that feel pointless. The pointless-feeling ones are the test.
• Give a clean mid-stream sample so results are not muddied by contamination.
• Learn the symptom list above and treat it as a same-hour list rather than a same-week one.
• Take aspirin if it has been recommended to you.

Protein on a dipstick is a signal to look harder, not a diagnosis. The system that finds it is working exactly as intended, and the follow-up is quick.