When Does Frequent Urination Start in Pregnancy?

Most people pee about seven to eight times per day on average. But when you’re pregnant, many of your body’s “on average” stats, including this one, don’t apply anymore. Along with all the other myriad ways your body changes during pregnancy, it can also cause you to have to pee more often — like, a lot more often.

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Ob/Gyn Erin Higgins, MD, explains why you have to pee more during pregnancy, including when to expect frequent urination and signs that it’s not just a run-of-the-mill pregnancy symptom.

What causes frequent urination in pregnancy?

There are two big reasons you’re likely to have to pee more often when you’re pregnant: added pressure on your bladder and pregnancy-related changes in the way your kidneys work. Let’s take a look at what’s happening in your body.

Added pressure on your bladder

When you’re pregnant, your uterus begins to stretch to make space for a growing fetus. This unique organ can expand from the size of a lemon to the size of a watermelon!

“You carry about 10 to 15 extra pounds in your uterus, including the fetus, placenta and fluids,” Dr. Higgins explains. “And all of that creates additional pressure on your bladder.”

She adds that an increase in the hormone progesterone helps loosen your ligaments and muscles to prepare your body to give birth. But that can also weaken your pelvic floor muscles and cause you to leak pee when you cough, sneeze or even laugh.

Changes in your kidneys

In early pregnancy, your kidneys start to process urine (pee) differently, which means that you literally make more pee than when you weren’t pregnant — which, of course, means you have to pee more often. Healthcare providers typically refer to something called glomerular filter rate (GFR), a measurement of how well the kidneys filter blood, to determine kidney health. But when you’re pregnant, your GFR can increase by a whopping 40% to 80%.

“We actually have to use different parameters for what normal kidney function looks like in pregnancy,” Dr. Higgins clarifies, “because these are normal physiologic changes that happen in pregnancy.”

When does it start?

Frequent urination can happen during all stages of pregnancy. Your GFR levels peak around week 13 and then start to level out — but that’s also riiiight around the time that your uterus really begins to expand.

Though some women do experience frequent urination in the first trimester, Dr. Higgins says it’s more common as pregnancy progresses. During the second half of your second trimester, you’re almost certain to be running to the bathroom more often than usual.

“At 12 weeks, your uterus is just starting to poke out of the lower pelvis, so it’s still very small,” she notes, “but by 20 weeks, it roughly corresponds with your belly button.”

Can having to pee often be a sign of pregnancy?

Frequent urination can be an early sign of pregnancy, as your body’s blood supply increases and your kidney function changes. But it’s not as common in the early days as it is later on.

In fact, Dr. Higgins says that having to pee a lot in the early days of pregnancy is often due to another reason. “If you’re having frequent urination in the first trimester, it could be a sign that you have a urinary tract infection (UTI),” she warns.

UTIs affect about 8% of pregnancies — and though that may not sound like much, it actually makes them pretty common. In addition to frequent urination, symptoms include:

A burning feeling when you pee
Blood in your urine
Changes in the color or smell of your urine
Pain during sex

Can frequent urination in pregnancy be prevented?

Sorry, but you’re not going to love this answer: There’s not much you can do about having to pee so darn often when you’re pregnant. But there are a few ways to maintain good urinary health, both during pregnancy and beyond.

Drink water earlier in the day. Nobody wants to have to get up in the middle of the night to pee. And while you may not be able to help it as your pregnancy progresses, you don’t have to contribute to it either. Try to front-load your hydration so you’re not chugging water right before bed.
Practice good wiping habits. Keep clean by always wiping front to back (never back to front!), which is one of the best ways to prevent UTIs.
Stay hydrated. This might sound crazy if you’re already peeing a lot. But good hydration is especially critical in pregnancy. Being well-hydrated helps fend off problems like fatigue, cramping and, yes, UTIs. So, aim for 64 to 96 ounces of water per day. Keep an eye on the color of your pee, too, to tell you how hydrated you are. “The lighter your urine, the better hydrated you are, while bright yellow-orange indicates dehydration,” Dr. Higgins says.

How long will it last?

Once the having-to-pee-all-the-time phase of pregnancy sets in, it’s not likely to pass until you’ve given birth. And even then, a weakened pelvic floor could mean that you experience leakage more often than you used to. Pelvic floor exercises can strengthen these muscles, which can help you avoid incontinence issues.

When to talk to your doctor

Having to pee a lot can be an unavoidable reality of pregnancy. But it shouldn’t bring other symptoms. Talk to your healthcare provider if you experience: