13 Weeks Pregnant

At 13 weeks, baby is the size of a Lipsmacker tube, and you’re officially in the second trimester.

By Babylist Staff

Medically Reviewed by Dr. Alyssa Dweck

Published Oct 27, 2022|Updated On Mar 26, 2025

Published Oct 27, 2022Updated On Mar 26, 2025

Our editors independently test and curate products. If you make a purchase via our links we may earn a commission.

Welcome to the second trimester! At 13 weeks gestation, your baby is the size of a Lipsmacker tube. They have developed their swallowing reflex, which they practice by drinking amniotic fluid (and then peeing it back out. Then repeating the process). You may be jumping right into the renewed energy of the second trimester, or you may still feel some morning sickness and fatigue.

What To Expect At 13 Weeks Pregnant

How Many Months Is 13 Weeks Pregnant?
Your Baby at 13 Weeks
Your Body at 13 Weeks Pregnant
Frequently Asked Questions About Life at 13 Weeks Pregnant
13 Weeks Pregnant Checklist

How Many Months Is 13 Weeks Pregnant?

Thirteen weeks pregnant in months is three-and-a-quarter months pregnant, which is part of the second trimester of pregnancy.

Your Baby at 13 Weeks

At 13 weeks, baby’s kidneys are developed and actively produce urine. That’s right—they’re peeing in utero (not pooping, though; that happens shortly after birth). Your baby is hard at work practicing their swallowing reflex and keeping those kidneys functioning by constantly drinking amniotic fluid, processing it, peeing it out and then doing it all over again.

How Big Is a Baby at 13 Weeks?

On average, a 13-week fetus measures about 2.1 inches and weighs 0.81 ounces. That’s about the size of a Lipsmacker tube.

Your Body at 13 Weeks of Pregnancy

As those less-than-fun first-trimester pregnancy symptoms begin to abate, here’s what you can expect to feel this week and in the weeks to come.

Increased sex drive

Feeling frisky? A boosted sex drive during pregnancy is completely normal, especially in the second trimester. Morning sickness and fatigue are likely fading, and still-rising estrogen is responsible for an increased libido, Dr. Mary Jane Minkin tells Babylist. Sex during pregnancy is completely safe, too (as long as you don’t have a condition that’s caused your doctor to advise against sex). Your babe is cocooned with amniotic fluid, and there’s a mucus plug to keep everything out. So have some fun if you feel like it!

Nausea

Morning sickness is known as an early pregnancy symptom, but it can stick around in the second trimester. If you’re still feeling ill, you’re likely heading down the home stretch by the time you hit week 13 of pregnancy. Tell your healthcare provider if you don’t get noticeably better in the next few weeks.

Heartburn

Have you traded nausea and fatigue for heartburn? More than half of pregnant women develop heartburn, especially in the second trimester, and you can thank the hormone relaxin for that. Relaxin relaxes your esophageal sphincter (the barrier between the esophagus and the stomach that keeps stomach acid out of your esophagus), so “stomach acid can creep up into the esophagus, causing heartburn,” Dr. Rachel Low tells Babylist. If you’re suffering, try to eat six small meals rather than three big ones. Other things to try if you’re trying to manage heartburn: eat more slowly, avoid spicy foods, prop yourself up when lying down and don’t lie down within 30 minutes after eating.

Stretch marks

These reddish streaks may start sprouting up on your belly, hips and breasts. Your skin is stretching like crazy, creating tiny tears in the top layer. Stretch marks tend to fade a bit after you give birth, but they’ll never go away completely, Dr. Nateya Carrington, ob-gyn and founder of Radiance Women’s Center, tells Babylist. Lotions or belly oils may help relieve any itching or tightness caused by stretch marks, but opt for types that are safe for sensitive skin since your skin is much more prone to irritation during pregnancy.

Pregnancy Symptoms Coming Up In Week 14:

Morning sickness may still affect you in week 14, and you might also be experiencing round ligament pain or varicose veins.

To-Do: Create Your Babylist

With Babylist, you can add any item from any store onto ONE registry. You’ll even get a Hello Baby Box full of free (amazing!) goodies.

Commonly Asked Questions About 13 Weeks Pregnant

How many calories should I eat while pregnant?

The total amount of calories you need during pregnancy depends on several things: your pre-pregnancy weight, which trimester you’re in and how much weight you’ve gained so far, registered dietitian Lyndsay Hall tells Babylist. On average, you should usually aim to get an extra 300-350 calories per day during the second trimester, which equates to an additional snack or small meal. Your healthcare provider should give you exact guidance on your caloric needs.

How can I prevent stretch marks?

If you’re naturally prone to stretch marks, you might not be able to avoid them. But regularly applying a good moisturizer or belly oil may keep them at bay longer and help them fade more quickly if they do appear. Even better, it gives you an excuse for a little TLC at the end of the day or after a shower. Lather up with Earth Mama Belly Butter or Burt’s Bees Mama Bee Belly Butter.

What is a ‘babymoon’?

You’ve heard of a honeymoon—a babymoon is essentially the same thing! It’s a getaway vacation just for you (and your partner if you have one, or a friend, if you want) before baby arrives. It’s a chance to relax, sleep, sightsee, do whatever you want before life as a new parent sets in. And now that you’re one-third of the way through your pregnancy, it’s a great time to start thinking about a babymoon. Go forth and brainstorm destinations—staycations count!—and make your travel plans. Just remember that if you decide to go during your third trimester your doctor may recommend you not fly. And you don’t want to plan a trip too close to your due date should your little one decide to come early. (If you haven’t figured out your due date yet, you can use our due date calculator.)

13 Weeks Pregnant Checklist

With your 12-week ultrasound behind you, now’s the time to book your anatomy scan, which usually happens around 20 weeks.
Decide how and when you’ll share your good news with your boss, coworkers and any friends or family who don’t know yet.
Thinking about a babymoon? Talk locations and start booking travel with your partner in crime.
If you haven’t already, think about starting a pregnancy journal to record this unique time in your life. Dedicate a blank-page journal to it, or if you want some structure, check out The Belly Book or Expecting You.

Sources

Dr. Nateya Carrington, ob-gyn and founder of Radiance Women’s Center
Dr. Rachel Low

13 Weeks Pregnant