13 Weeks Pregnant: Symptoms & Baby Development - Babylist
13 Weeks Pregnant
October 27, 2022

13 Weeks Pregnant

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13 Weeks Pregnant.
13 Weeks Pregnant

Welcome to the second trimester! At 13 weeks gestation, your baby has 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.

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 2.9 inches and weighs 0.81 ounces. That’s about the size of a Tamagotchi.

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!


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. If you don’t get noticeably better in the next few weeks, tell your healthcare provider.


Have you traded nausea and fatigue for heartburn? More than half of pregnant people 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 eating six small meals rather than three big ones. Other things to try: eat more slowly, avoid spicy foods, prop yourself up when laying down and don’t lay 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 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.

13 Weeks Pregnant Ultrasound


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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, pregnant people usually aim to get an extra 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 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.

Recommended Products for Week 13 of Pregnancy

If you are experiencing heartburn at this phase, there are some options for relief. You also might want to document this very special time. We have some suggestions for doing all of the above.

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.
This information is provided for educational and entertainment purposes only. We do not accept any responsibility for any liability, loss or risk, personal or otherwise, incurred as a consequence, directly or indirectly, from any information or advice contained here. Babylist may earn compensation from affiliate links in this content. Learn more about how we write Babylist content and the Babylist Health Advisory Board.