Protein in Urine During Pregnancy: What It Means and When to Worry

Pregnancy is a time of increased doctor's visits and close scrutiny of one's health. There may also be a lot of tests that you haven't encountered before, especially if your pregnancy is (or becomes) complicated. 

One screening that might be ordered is a test for the amount of protein in a pregnant person's urine. There are several ways protein in urine in pregnancy might be tested, and we'll break down what causes protein in urine, what a result of high protein in urine during pregnancy means, why these tests might be ordered, and importantly, when to worry. 

A very high amount of protein in anyone's urine, formally called proteinuria, can be a sign of kidney problems. In pregnancy specifically, it's an indication of preeclampsia when combined with high blood pressure after 20 weeks' gestation. Because preeclampsia can be very serious, a high amount of protein in the urine during pregnancy can be a real cause for concern. But first we need to back up. Not every trace of protein in urine during pregnancy is cause for concern. 

Everyone has some amount of protein in their urine and the normal range of protein levels in urine during pregnancy are generally higher, from 150 milligrams per day to 300. So a pregnant person will generally have more protein in their urine than someone not carrying a baby. During pregnancy, a value above 300 mg per day is considered high.

The American College of Obstetrics and Gynecology no longer recommends that providers routinely screen the urine of pregnant women for protein. The exception is for women who have a history of or risk factors for certain disorders, like high blood pressure or diabetes, says Alice Abernathy, M.D., an OBGYN and currently a National Clinician Scholar at UPenn. In those cases, doctors may perform an initial test of the amount of protein in urine in order to establish a baseline level. Knowing this level early in a pregnancy allows a provider to monitor whether it's increasing. In some cases, a pregnant person can have a high, but stable, amount of protein in their urine. Protein in urine during pregnancy without high blood pressure may not be a concern. 

Dr. Abernathy said in those cases, or if the woman's protein levels are high before 20 weeks, she'd probably chalk it up to a previously undiagnosed issue. She'd keep an eye on it, but it wouldn't necessarily be a cause for concern. 

If a pregnant patient's blood pressure started creeping up, or they presented with neurological symptoms (like severe headache or excessive abnormal weight gain), Dr. Abernathy said she'd check for protein in the urine. 

Traditionally, testing for protein in urine was done with an in-office dipstick test. However, this test doesn't measure an exact amount of protein, just a range from low to high. It's also vulnerable to daily fluctuations in protein levels. Instead, Dr. Abernathy says that when she has concerns about a patient's blood pressure she prefers a test of the protein-to-creatinine ratio in urine, along with blood tests to check liver function. If the protein-to-creatinine ratio comes back high, then the gold standard test is a 24-hour urine collection (Yes, it's exactly what it sounds like. You hoard all your pee for a day and drop it off at the lab.).

If a patient has high blood pressure but no elevated protein levels, then they're in gestational hypertension territory. When high blood pressure and high protein in the urine occur together in pregnancy, preeclampsia is a concern. 

Preeclampsia can be dangerous if it progresses. When accompanied by severe complications, hospitalization may be required and an early delivery scheduled. If you experience high blood pressure in your pregnancy (and also if it becomes preeclampsia), you should expect increased monitoring and more frequent doctor's visits.

If you have preeclampsia, you'll probably have a conversation with your doctor about a delivery at 37 weeks, Dr. Abernathy said. That's the point (technically called "early full term") at which there tends to be very few complications from delivery for the baby. Therefore, it's better not to risk the mother's health by continuing to wait.

While preeclampsia has historically been a driver of bad maternal health outcomes, doctors now are "very vigilant about it and we try to diagnose it early," says Dr. Abernathy. 

Since high protein in urine is an indicator of other problems, it's not something that's usually treated directly, though it may be monitored after delivery if a doctor suspects a cause other than pregnancy. There's no real way to reduce protein in urine in pregnancy, Dr. Abernathy said. Instead, it would be monitored along the guidelines laid out above and delivery would be considered if preeclampsia develops. 

It's important to remember that preeclampsia is in many ways the (bad) luck of the draw. There's not much a pregnant person can do to really prevent the condition (or prevent high protein in the urine), Dr. Abernathy said. If you have a history of high blood pressure, your doctor might recommend taking a baby aspirin, which has been shown to be beneficial for people at an elevated risk of developing preeclampsia. 

"So many people who have preeclampsia just are prone to developing hypertension and they're going to have high blood pressure issues when they're older," she says.