It may feel as if there's no way your tummy can stretch any more than it already has, but there's no doubt about it — your baby bump will get a lot bigger over the course of the third trimester of pregnancy.

Here’s what to expect from your body and your rapidly maturing baby in these final few weeks.

When does the third trimester start?

The third trimester begins around week 28 of pregnancy and lasts until you give birth, which may be around week 40 of pregnancy. In other words, your third trimester lasts from around week 28 to week 40, or months 7 to 9 of pregnancy. In total, the third trimester is about 13 weeks long.

It’s likely, however, that labor will start a couple of weeks earlier or later — in fact, about 30 percent of all babies linger past the 40-week mark. If that's the case, you can try a few tricks to naturally induce labor on your own, but once you reach around week 41 or week 42 of pregnancy (depending on your medical practice and circumstances), you'll likely be considered overdue. At that point your doctor may decide to induce labor if it doesn’t begin on its own. 

In the meantime, hang in there! You’re almost to the finish line.

What are the symptoms of third trimester pregnancy?

With that busy baby inside your belly, you're probably feeling lots of fetal activity. You may also be experiencing changes in your body as your bump gets bigger and bigger, including: 

  • Nausea. Morning sickness tends to subside after the first trimester, but it’s possible — especially if you’re expecting twins or multiples — for nausea to linger up until you give birth.

  • Headache. Smells, a lack of sleep, stress, overheating and other factors can all trigger headache or migraineduring your third trimester. Try to stick to a regular eating, exercise and sleep routine, and give yourself some much needed quiet time to de-stress.

  • Diarrhea. As your body gears up for delivery, some of the muscles in your body — including the rectum — loosen up, causing what’s known as prelabor diarrhea. Still a few weeks (or months) shy of your due date? It might be a result of all that extra fiber in your diet, or even a stomach bug. If your symptoms linger for more than a few days, call your doctor.  

  • Abdominal achiness. As your round ligaments (which support your lower abdomen) stretch to accommodate your growing bump, you may feel cramps or sharp pain. There’s not much you can do other than take it easy.

  • Lightning crotch. No one’s really sure what causes lightning crotch — a sudden, sharp shock to the (you guessed it) crotch area — but one theory is that baby is pressing on a nerve that runs to the cervix. Other than change positions, there’s not much you can do about the pain besides wait it out. It should only last for a few seconds, however. Pain that goes on any longer warrants a call to your doctor.

  • Fatigue. You’ll feel more zapped this trimester because of the demands pregnancy is putting on your body, so eat well and frequently, stay active and minimize pregnancy sleep problems.

  • Heartburn (acid reflux). In the last few weeks of pregnancy, your uterus will push your stomach and its contents upward, causing that persistent burn. If it’s really bothering you, talk to your doctor about proton-pump inhibitors (PPIs) or H2 blockers, which are safe to use during pregnancy.

  • Braxton Hicks contractions. Your body’s way of preparing for labor, you’ll start to feel these irregular practice contractions around now until real labor starts.

  • Varicose veins. You may notice these bulging veins (including hemorrhoids, which are actually a type of varicose vein) in your lower body due to all of the extra blood you’re pumping. The good news: If you didn’t have them before pregnancy, they’ll likely disappear after you deliver.

  • Stretch marks. These tiny tears, which appear in skin that’s being stretched to the limit during pregnancy, are usually a result of genetics. Moisturize to minimize their appearance.

  • Backache. As the pregnancy hormone relaxin loosens your joints and your growing belly pulls your center of gravity forward, you may start to have an achy back — another reason to put your feet up, literally. (Sharp, shooting pain from your back down your legs, on the other hand, may be a sign of sciatica.)

  • Insomnia. Leg cramps, constant trips to the bathroom and just general aches and pains (not to mention all those other pregnancy symptoms you’re experiencing) can all seriously interfere with your shut-eye. In fact, insomnia affects more than 75 percent of the expectant set. A few sleepless nights are probably no big deal, but if the problem continues, talk to your doctor about ways to manage sleeplessness. You might be able to take melatonin or a magnesium supplement. 

  • Crazy dreams. Thanks to pregnancy hormones, your dreams may be more vivid than ever as you near your due date. They’re totally normal — so take them with a grain of salt and have fun swapping stories with a loved one.

  • Clumsiness. Your hormones are on overdrive, your belly is throwing you off balance and you’re more forgetful than ever. You’re in good (pregnant) company — so just try to be careful and have a sense of humor about it!

  • Lack of bladder control. You sneeze = you pee. Indeed, all that extra weight on your pelvic floor makes it harder to stay dry. To the rescue: Your daily Kegels regimen.

  • Leaky breasts. Your body’s warming up to feed your baby.

  • Weight gain. Your baby is packing on the pounds, but your weight will likely slow down as you near delivery day. It’s not unusual to gain around 8 to 10 pounds this trimester. It’s also normal if you lose a few pounds at the end of your ninth month.

With all these pregnancy symptoms and more weighing on you, just try to keep your eye on the prize: your beautiful baby, whom you'll meet in just a few weeks!

When should I worry about my third trimester?

You’ll likely want to head to the hospital around the time active labor starts, when baby is on the way (though check with your doctor to be sure).  

As delivery day approaches, you may experience false labor symptoms — but the real signs of labor to watch out for include:

  • Baby dropping. By about week 36, you may find yourself waddling as your baby drops into your pelvis. 

  • Bloody show. This stringy mucus tinged pink or brown with blood is a sure sign labor is well on its way. You also may or may not notice the discharge of your mucus plug (which seals off your uterus from the outside world).

  • Pelvic pressure. Crampiness in the groin area can be a sign of labor as your cervix starts to dilate and thin out.

  • Labor contractions. Compared to Braxton Hicks contractions, these intensify, rather than diminish, the more you move around.

  • Your water breakingThis may not even happen, however, until you’re already at the hospital.

Call your doctor, however, if you start to experience signs of preterm labor or any of the following late-pregnancy warning symptoms:

  • Heavy vaginal bleeding

  • Severe vaginal pain

  • Severe pain in the lower abdomen

  • A fever over 101.5 Fahrenheit 

  • Severe lower abdominal pain

  • Sudden weight gain

Remember: You’re always better trusting your instincts and staying on the safe side when you’re expecting.

How much does a baby grow during the third trimester?

Your little one will get a whole lot larger in the third trimester, growing from about 2 1/2 pounds and 16 inches long in week 28 of pregnancy to between 6 and 9 pounds and 19 to 22 inches long in week 40. Because your baby is growing so fast, don't be surprised if that growth spurt (along with a decrease in living space) leads to some serious kicks and pokes in your gut.

Here are a few of the highlights of your third trimester of pregnancy:

  • Bones. As cartilage transforms to bone in months 7 and 8, your baby will be getting calcium from you — so be sure to eat plenty of calcium-rich foods.

  • Hair, skin and nails. By week 32 of pregnancy, baby’s formerly see-through skin will become opaque. In week 36, fat continues to accumulate as your baby sheds vernix (the waxy substance that protects the skin from your amniotic fluid) and lanugo (the warm, hairy coat).

  • Digestive system. In the final weeks of pregnancy, meconium — or baby’s first poop, consisting mostly of blood cells, vernix and lanugo — starts to build up in baby’s intestines.

  • Five senses. Your baby’s touch receptors will be fully developed around week 29 or week 30. By week 31 of pregnancy, your baby will get signals from all five senses, perceiving light and dark, tasting what you eat, and listening to the sound of your voice.

  • Brain. In the third trimester your baby’s brain will grow faster than ever, test-driving some nifty skills including blinking, dreaming and regulating body temperature. 

Around week 34 of pregnancy, baby’s body turns southward, settling into a heads-down, bottom-up position — unless, of course, your baby remains stubbornly in the breech position, in which case your doctor will likely attempt to manually turn baby around week 37.

Third trimester checklist

You’re nearing the home stretch, but there’s plenty to do in the meantime. Here are the top to-dos for the third trimester.

  • Keep track of fetal movement. From about week 28 on, you’ll want to count baby’s kicks regularly and note any changes in activity, especially during month 9.

  • Watch your weight. Your pregnancy weight gain will pick up speed at the beginning of the third trimester and slow down as your due date nears. You may even lose a pound or two. If you’re not gaining enough, or if you’ve gained too much, work with your doctor to adjust your pregnancy diet to get back on track.

  • Keep moving! As long as you have your practitioner’s okay and you follow a few fitness safety precautions, it’s safe to keep doing your pregnancy-safe exercises up until your due date.

  • Schedule your third trimester checkups. Expect your glucose screening by about week 28 (or the start of month 7) if you haven't had it already, an anemia test around month 7, and your group B strep test in month 9. Also in your ninth month, your practitioner will perform an internal examination of your cervix to see if effacement and dilation (the thinning and opening of your cervix) have begun. If you’re classified as “high-risk,” your doctor may also schedule a biophysical profile or nonstress test in the last few weeks just to be sure everything is proceeding as expected.

  • Take a hospital tour. If you haven’t already, month 7 is a great time to take a tour of the hospital or birthing center where you plan to give birth.

  • Choose your baby’s pediatrician. Interview a few candidates with a list of questions around week 32 and pick your favorite.

  • Buy baby gear. Make sure you have the baby gear essentials — especially a crib, stroller, car seat (which you’ll need to bring your baby home from the hospital), changing table and baby monitor. On that note, take your car seat in to be professionally installed.

  • Get educated. In addition to a childbirth class — which will help you to feel more prepared for the entire birth process — you may also want to consider classes on infant CPR and baby care.

  • Prepare to breastfeed, if you plan to. The best time to learn about breastfeeding is before baby arrives. You might even want to take a breastfeeding class, or hire doula or a lactation consultant for advice or help now or later if you need it.

  • Learn about the stages of labor. Get prepared for baby’s birthday by learning what to expect during early, active and transitional labor as well as pushing baby out and delivering the placenta.

  • Consider how you’d like to manage labor pain. Want an epidural or other medication to manage labor pain? Thinking about having a natural birth, possibly in a birthing tub? Now’s the time to discuss your options with your practitioner.

  • Check your birth plan. From whether or not you want an epidural to when and who cuts baby’s umbilical cord, make or finalize your birth plan. (Just remember, when it comes time to push baby out, not everything always goes exactly as planned — the important part is keeping you and your baby safe and healthy!)

  • Set up your nursery. Get all of the essentials you’ll need for your nursery. And don’t forget baby basics like bottles, baby clothes, diapers, wipes, pacifiers and formula (if you’re not planning to breastfeed).

  • Commemorate your baby bump. Take some beautiful bump shots — you can hang them in the nursery or add to your baby’s photo album later.

  • Stock your fridge. You may want to whip up a few meals to keep in your freezer for the first few weeks, when you’ll be busy with a new baby and recovering from birth.

  • Plan financially. The costs of having a baby can add up quickly, so make a new family budget and start following it accordingly.

  • Pack your hospital bag. Pack light — but don’t forget a few comforts from home that you’ll want to have with you at the hospital.

  • Arrange for cord blood banking. If you’re considering cord blood banking — public or private — be sure your practitioner is aware of your plans, and don’t forget to pack any cord blood kit the bank sends you in your hospital bag.

  • Learn what happens after birth. Read up on what happens after birth as your body repairs and you begin to adjust to your new role.

  • Prepare for baby’s first year. Learn more about all the exciting milestones that happen in baby’s first year of life — there’s so much to look forward to!

What to avoid during the third trimester

With your burgeoning belly and lower-than-usual energy levels, you might not be doing very much of anything these days. The good news: Now that you’re in your third trimester, you don’t have long to go. Here are a few things to avoid in your third trimester — you’ll be able to do many of them again soon! 

  • Traveling. This may be stating the obvious, but if your due date is nearing, you probably don’t want to venture too far from home. Plus, some modes of transportation — like air travel, for example — are off-limits after around 36 weeks of pregnancy (and maybe sooner), depending on the airline’s policy.   

  • Lying on your back. Chances are, you haven’t been sleeping or doing exercises on your stomach for a few months now. But you should also avoid lying flat on your back during pregnancy, since the entire weight of your uterus and baby can compress the vein that carries blood from your lower body to your heart, causing you to feel nauseous and short of breath.

  • Hot tubs and saunas. You’ve never needed a long soak more — and yet, you’ll still need to avoid hot tubs and saunas (specifically, anything that raises your internal temperature to more than 101 degrees F) until you deliver. If you do take a bath, keep the water at around 97 to 98 degrees F and monitor the levels with a thermometer. And, of course, be careful not to lose your balance in the tub.

  • Exercising in warm temperatures. You don’t have to stop working out during your third trimester, but you should avoid exercising in hot weather. Now is not the time to try hot (Bikram) yoga, after all. Stay indoors to reduce your odds of overheating or becoming dehydrated.

  • Alcohol. No amount of alcohol has been shown to be safe at any point during pregnancy — so make it a mocktail. 

  • Raw or undercooked foods. Raw and undercooked foods (mainly poultry, eggs, meat or fish) can harbor infection-causing bacteria, so keep them off the menu for the remainder of your pregnancy.

  • Unpasteurized dairy and juices. You may not encounter unpasteurized milk or juices very often, but you may run across certain cheeses that have been made with unpasteurized milk. Soft cheeses, like Brie, goat, and feta, are common culprits, for example. Check the label to make sure the product has been made with pasteurized ingredients.

Getting excited? You should be — it won't be long now until you meet your baby!