What To Expect in Your 3rd Trimester

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If you’re entering or already in your third trimester of pregnancy, congrats! You’ve made it to the homestretch and your baby’s birthday is just around the corner. Now is the time to start taking childbirth classes—especially if this will be your first kid—and make sure you’re set with all your nursery, delivery, and diaper bag must-haves. Your doctor or midwife will likely want to see you a bit more often in the third trimester of pregnancy (typically every couple of weeks or so versus monthly, then once a week in your final month). And it helps to know what to expect in your third trimester, so you can prepare mentally and physically for any challenges ahead.

Keep reading to learn all about what to expect in the third trimester. We’re sharing how many third trimester weeks there are (up to a full-term birth), as well as common third trimester symptoms. Plus, you’ll learn how your little bun in the oven is developing week by week along the way.

Mommy Pro Tip: Psst . . . Your third trimester is also a great time to stock up on Infants’ Mylicon Gas Relief Drops in our dye-free or original formula, so you’ll have them on hand to help quickly relieve your baby’s gassy belly. They’re safe for even the newest of newborns, and can be used at every feeding—up to 12 times a day.

When Does the Third Trimester Start?

First, we should note that you may hear the terms “gestational age” and “fetal age” when referring to how far along you are. Gestational age, or the progression of your pregnancy, is calculated starting from the first day of your last normal period before you got pregnant. The fetal age is actually how old your infant is from the time they were conceived, usually about two weeks into your cycle. So, your third trimester rings in at 28 weeks (seven months), when your baby is 26 weeks old in utero. And a pregnancy that goes the distance full-term is considered 40 weeks long based on gestation (38 since conception).

Mommy Pro Tip: Be sure to put together your birth plan well ahead of your due date. Print and fill out this handy birth plan template to be sure everyone knows what your wishes are during labor, delivery, and when your infant arrives.

What To Expect in Your Third Trimester

Of the many changes your body goes through while pregnant, perhaps the most dramatic one—aside from growing a tiny human, of course—is your uterus expanding from its original size of about two ounces (the size of an orange) to around two-and-a-half pounds (the size of a watermelon) by the end of your third trimester. Needless to say, this can cause a range of third trimester symptoms, from sleep issues to some pretty common yet uncomfortable tummy troubles while pregnant. Below, we’re going into what they are and why they occur.

Common Third Trimester Symptoms

Third trimester symptoms may be prevalent, but that doesn’t make them any less bothersome to deal with. Often, they cause discomfort and even pain in the third trimester, so be sure to let your doctor know what you’re experiencing so they can help you get as much relief as possible.

Insomnia: You may have had trouble sleeping in your first trimester, but that was likely due to a surge in the pregnancy hormone progesterone. In your third trimester, your baby bump may make it difficult to find a comfortable position to doze off in.

Feeling hot: Your brewing baby is a little heat machine, who can radiate warmth that makes you feel hotter than normal.

Tired & lightheaded: Your infant is pressing on a major vein that sends blood back to your heart, so your blood pressure may decrease, causing you to feel lightheaded, dizzy, tired, or unable to concentrate, among other symptoms of general unwellness.

Pregnancy brain: You may also experience a mental fog and frequent forgetfulness known as pregnancy brain—which is no myth. However, there are some surprising mommying benefits it provides.

Frequent urges to pee: If you're keeping a mental note of where the restroom is in every place you enter, there's a good reason why. The weight of your little one is pressing on your bladder. This can also cause leaks when you cough, laugh, sneeze, bend, or lift something, which panty liners can help absorb.

Water retention: When you’re pregnant, you have about 60% more blood volume, which can result in extra fluid pooling in your lower limbs, especially your ankles and feet. (So try to prop those mommy-to-be feet up as much as possible when you can or use compression socks.)

Spider veins and varicose veins: Ramped up blood circulation can also cause small purplish-red spider veins on your face, neck, and arms, as well as knotted, swollen varicose veins on your legs (yet another reason to keep those legs propped up).

Leg cramps or restless leg syndrome: Particularly in the evening, your legs may feel uncomfortable or like they’re cramping, throbbing, or burning, which could be related to the water retention. Try massaging them or walking around.

Increased, coarser body hair: A rise in hormones can stimulate your hair follicles, which can be a great perk for the hair on your head, but you may notice more hair on your arms, legs, and face.

Stretch marks: Your baby bump grows in a relatively short amount of time, which can result in stretch marks appearing on your belly, breasts, buttocks, and thighs.

Dry, itchy skin: All the expansion and stretching your skin goes through can also result in dry and/or itchy skin.

Dark patches on the face: Known as melasma, it’s common for skin to produce too much pigment in patches on the face. And unprotected sun exposure and irritating skincare products can worsen them, especially if you have a dark skin tone.

Swollen breasts: Hormonal changes prep your breasts to feed your new baby, so during the third trimester it’s not unusual to go up a few bra cup sizes. If you had smaller breasts to begin with, they may be slightly more painful than women who already had large breasts. Be sure to invest in larger bras, since tighter ones can inhibit breast milk production.

Upset stomach: Since your infant is taking up precious real estate in your body, they’re pressing on your internal organs like your esophagus, stomach, and intestines. This can cause a range of gastrointestinal issues like nausea, heartburn, gastroesophageal reflux disease (GERD), diarrhea, and constipation. The latter of which can increase your risk for hemorrhoids.

Back & hip pain: When you’re pregnant, elevated levels of progesterone relax your joints and muscles to provide increased flexibility, but this can also cause you to become imbalanced and increase pressure on your lower back and hips. You’re carrying around more weight than usual, too, which can only compound the problem.

Postpartum anxiety & postpartum depression: Despite their names, both of these mood disorders are perinatal, meaning they can occur before or after giving birth. One in seven women experience postpartum anxiety and one in eight experience postpartum depression.

Shortness of breath: All the extra weight, strain, and reduced space for your internal organs can cause you to get winded more easily. As often as you can, remind yourself to sit up or stand up as straight as you can to give your lungs extra room to expand.

Braxton Hicks contractions: You may feel a slight tightness in your belly and mild, irregular contractions that occur more commonly in the afternoon and evening, or following physical activity or sex. They may become more frequent and strong the closer to your due date you get, so keep an eye on them and let your doctor or midwife know if they become more frequent or intense. That could be a sign your baby is on the way!

Your Third Trimester in Weeks

Before we get into the fun stuff—your growing baby!—we should note that these third trimester weeks are counted with regards to gestational age. They can vary mom to mom, baby to baby, but are generally as follows.

Pregnancy week 28 (26-week fetal age): For the very first time, your little one will open their eyelids slightly and have a full set up eyelashes. Your baby might be as long as 10 inches from the tippy-top of their head to their bum and weigh close to two-and-a-quarter pounds. And they can make breathing movements.

Pregnancy week 29 (27-week fetal age): You may have felt your baby kick around 18 to 20 weeks into your pregnancy. But by 29 weeks, they’re really moving! They can now kick, stretch, and make grasping motions with those itty-bitty, little hands.

Pregnancy week 30 (28-week fetal age): Your infant can now open their eyes up wide, and may even have a decent amount of hair on their head. They may be over 10-and-a-half inches long and weigh around 3 pounds.

Pregnancy week 31 (29-week fetal age): Here’s when your baby starts packing it on for the first time! Since most of their major development is achieved, they’ll focus on quickly beefing up.

Pregnancy week 32 (30-week fetal age): Now, your little one may practice breathing in the womb. Soft, downy hair called “lanugo” that covered their skin over the past few months starts to shed. And miniature little toenails are visible. (Too cute!) They may be 11 inches long and weigh three-and-a-quarter pounds.

Pregnancy week 33 (31-week fetal age): They’re getting their very first taste of the world outside them with the new ability to detect light, which causes their pupils to dilate. Their bones are hardening, but their skull is still soft and flexible to help with delivery.

Pregnancy week 34 (32-week fetal age): They could be about a foot long and weigh four-and-a-half pounds by now. And be still our hearts: Your infant’s teensy-weensy fingernails are now on display.

Pregnancy week 35 (33-week fetal age): They’ve been putting on some weight over the last few weeks, so now your infant is looking more and more cherubic. Their skin is also becoming super smooth and soft.

Pregnancy week 36 (34-week fetal age): Things are starting to get a little cramped, as your baby begins to fill in your uterus. Fortunately, this makes it harder for them to give you an ol’ one-two punch, but you should still be able to feel them rolling around, stretching, and wiggling.

Pregnancy week 37 (35-week fetal age): If it were possible to grab their chubby little hand, you’d be able to feel that your little one has quite a firm grasp for someone so tiny. They may also start getting into position for delivery, with their head moving downward. If for some reason it’s not, your doctor or midwife will be able to give you some options to help it along.

Pregnancy week 38 (36-week fetal age): Almost all of the lanugo should be gone by now, and your infant's toenails have grown to the tips of their toes. Their head is about the same circumference as the rest of their tummy, and they may weigh around six-and-a-half pounds.

Pregnancy week 39 (37-week fetal age): You’ve both come so far—you’re almost there! More chub is added to their body to help keep them warm once born, and their chest is becoming more prominent. If it’s a boy, their testes will descend further into their scrotum.

Pregnancy week 40 (38-week fetal age): Brace yourself, your life is about to change forever. This is the week of your likely due date. Your little one may arrive at any moment!

Next: Those are just the beginning of the many milestones your child will hit. Find out what the big ones are in their first 18 months.


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