The Third Trimester of Pregnancy: Weight Gain & Other Changes

Welcome to the third trimester: the part of pregnancy where your baby is busy “powering up,” your body is auditioning
for a role in a very dramatic reality show, and strangers suddenly feel invited to say things like, “Whoa, you’re about to pop!”
(Spoiler: you are not a balloon. You are a person.)

This guide breaks down what’s normal in the home stretchespecially weight gainplus the most common body changes,
what can help, what deserves a call to your clinician, and how to keep your sanity while your socks quietly declare independence.

When the Third Trimester Starts (and Why It Feels So Intense)

The third trimester typically runs from about week 28 through week 40 (and sometimes a little beyond, depending on when
your baby decides to make their grand entrance). During these weeks, baby growth accelerates, your uterus takes up more real estate,
and many earlier symptoms returnoften with a little extra flair.

Third-Trimester Weight Gain: What’s Typical

First: Total pregnancy weight-gain ranges (singleton pregnancies)

“How much should I gain?” is a fair questionbecause pregnancy is the one time in life where your body is doing construction,
expansion, plumbing upgrades, and interior decorating all at once. Recommended totals usually depend on your pre-pregnancy BMI.
Here are commonly cited ranges for a single baby:

Important reality check: weight gain isn’t perfectly linear. You might gain more some weeks (hello, fluid shifts) and less others.
What matters most is the overall trend and how you and baby are doingsomething your prenatal team tracks for a reason.

Typical rate of gain in weeks 28–40

After the first trimester, many guidelines describe a general weekly pace (again, based on pre-pregnancy BMI). A commonly used range looks like this:

If your numbers are outside these ranges, it doesn’t automatically mean anything is “wrong.” It’s a prompt to talk with your provider about
nutrition, swelling, nausea, activity, sleep, stress, and whether any medical issues (like blood pressure concerns) could be playing a role.

Where the weight actually goes (hint: not all of it is “fat”)

It can feel unfair that you gain more than the baby’s birth weight. But pregnancy weight is a whole cast of characters:

• Baby
• Placenta
• Amniotic fluid
• Increased blood volume (your body basically upgrades to “extra plumbing” mode)
• Extra fluid volume (hello, swelling)
• Breast and uterine growth
• Fat stores (energy reserves for late pregnancy and postpartum)

Many credible medical resources show examples of how a ~25–35 lb gain can break down across these components.
Translation: your body isn’t “randomly gaining.” It’s building a life-support system.

Calories in the third trimester: the “extra 450” headline (and what it means in real food)

You may see guidance suggesting roughly ~450 extra calories per day in the third trimester for many pregnant people.
That’s not a mandate to count every crumbit’s a reminder that your energy needs often increase.

In practice, ~450 calories might look like:

• Greek yogurt + berries + a handful of granola
• Peanut butter on whole-grain toast + a banana
• Trail mix (nuts + dried fruit) + string cheese
• Hummus + pita + crunchy veggies

If heartburn is raging, aim for smaller, more frequent meals and snacksbecause giant meals in the third trimester can feel like trying
to park a bus in a compact spot.

Common Third-Trimester Body Changes (and What Can Help)

1) Shortness of breath

As the baby grows, your uterus can crowd your diaphragm. You might get winded walking up stairs or even during enthusiastic storytelling.
Good posture and side-lying rest can help. If shortness of breath is sudden, severe, or comes with chest pain, fever, or a racing heartbeat,
get urgent medical advice.

2) Heartburn and reflux

Hormones relax smooth muscles, and the growing uterus adds pressureso stomach acid may travel like it owns the place.
Helpful strategies include smaller meals, avoiding trigger foods, staying upright after eating, and asking your provider which antacids are pregnancy-safe.

3) Swelling (edema), especially in feet and ankles

Mild swelling is common. Elevate your feet when you can, stay hydrated, and consider supportive footwear. Compression socks can also be helpful for some.
Call your provider if swelling is sudden or severe, especially in the face/hands, or if it comes with headaches or vision changes.

4) Frequent urination (again)

Baby’s head and the uterus press on your bladder, so you may feel like you live in the bathroom now. Hydration still mattersjust try shifting
more fluids earlier in the day if nighttime trips are stealing your sleep.

5) Back pain and sciatica

Weight gain, posture changes, and loosened ligaments can strain your lower back. Some people also feel sciatic nerve pain (shooting pain down the leg).
Support belts, prenatal stretching, warm showers, and provider-approved exercise can help. If pain is severe or you have numbness/weakness, check in.

6) Pelvic pressure and “lightning crotch” moments

When baby drops lower (engagement), you may feel increased pressure or sharp, brief pains. Changing positions slowly, wearing support garments,
and rest can make it more manageable. If you have persistent severe pain, bleeding, or contractions, contact your provider.

7) Braxton Hicks contractions

These “practice contractions” can feel like tightening across the belly. They’re often irregular and improve with hydration, rest, or changing positions.
If contractions become regular, more painful, closer together, or you’re under 37 weeks, call your provider to rule out preterm labor.

8) Sleep trouble

Between bathroom trips, heartburn, anxiety-excitement, and the fact that you can’t find a comfortable position even with six pillows,
sleep can get choppy. Side-sleeping is commonly recommended later in pregnancy. Try a consistent wind-down routine, limiting screens,
and using pillows for belly and hip support.

9) Leg cramps and restless legs

Gentle calf stretches, hydration, and talking with your provider about magnesium or iron (if appropriate) can help. If you have one leg that’s
suddenly swollen, painful, warm, or red, seek medical evaluation promptly.

10) Constipation and hemorrhoids

Hormones slow digestion, iron supplements can contribute, and pressure increases. Fiber-rich foods, fluids, gentle movement, and provider-approved stool softeners
can help. For hemorrhoids, warm sitz baths and topical treatments approved by your clinician may bring relief.

11) Skin changes: itchiness, stretch marks, and “why is everything tighter?”

Itching can come from skin stretching and drynessmoisturizing helps. But intense itching (especially on palms/soles) should be reported to your provider.
Stretch marks are common and largely genetic; moisturizers can reduce dryness and irritation, even if they can’t erase biology’s handwriting.

12) Mood swings and brain fog

The third trimester is emotionally loaded: excitement, worry, discomfort, and the strange urge to reorganize the spice cabinet at 2 a.m.
If anxiety or low mood feels persistent or overwhelming, tell your provider. Support is part of prenatal care, not a bonus feature.

What Your Baby Is Doing in the Third Trimester

The third trimester is prime time for growth and finishing touches. Babies typically gain weight rapidly, store fat, and continue developing the brain and lungs.
Movement patterns can feel different as space gets tightermore rolls and stretches, fewer dramatic karate kicksbut you should still notice regular activity.

Prenatal Visits and Common Third-Trimester Tests

How often are visits?

Many people have prenatal visits about every 2 to 4 weeks in the third trimester, and then more frequently after 36 weeks
(often every 1 to 2 weeks) depending on health history and pregnancy needs.

Common screenings and care topics

• Group B strep (GBS) screening: typically done around 36–37 weeks. If positive, antibiotics during labor can reduce baby’s risk of infection.
• Vaccines: Many guidelines recommend Tdap during 27–36 weeks to help protect newborns from whooping cough.
  Depending on season and availability, some people may also be offered a maternal RSV vaccine during 32–36 weeks in certain months.
  Your provider will also advise about flu vaccination when appropriate.
• Rh factor care: If you’re Rh-negative, you may receive Rh immune globulin around 28 weeks (and possibly again after delivery, depending on baby’s blood type).
• Blood pressure and urine checks: prenatal visits monitor for conditions like gestational hypertension and preeclampsia.
• Additional monitoring (if needed): some pregnancies require ultrasounds, nonstress tests, or extra lab work based on risk factors.

Kick Counts: A Simple Way to Track Baby’s Well-Being

Many clinicians suggest paying closer attention to fetal movement in the third trimester. One common approach is the “count to 10” method:
choose a time when your baby is usually active, get comfortable, and count movements until you reach 10.
Some guidance considers 10 movements within 2 hours reassuring (many babies do it much faster).

If you notice a major change from your baby’s usual patternor you can’t get reassuring movement after trying againcontact your provider.
Trusting your instincts is not “overreacting.” It’s information.

When to Call Your Provider Right Away

Some symptoms deserve quick attention. Call your OB/midwife or seek urgent care if you have:

• Vaginal bleeding or passing clots
• Leaking fluid (possible rupture of membranes)
• Regular painful contractions, especially before 37 weeks
• Severe headache that doesn’t improve
• Vision changes (spots, blur, flashing lights)
• Sudden swelling of face/hands or rapid swelling with other symptoms
• Severe upper abdominal pain (especially right-sided) or severe nausea/vomiting late in pregnancy
• Decreased fetal movement compared with your baby’s normal pattern
• Fever, chills, or symptoms that feel like “something is really off”
• Shortness of breath that is sudden/severe or occurs with chest pain

Your provider would rather hear from you and reassure you than have you sitting at home googling “is this normal” at 3 a.m. (Ask me how I know.
Actually don’tI’m not the one who’s pregnant. But the internet is dramatic.)

How to Support Healthy Weight Gain Without Obsessing

Build your plate like a grown-up (with snacks like a genius)

• Protein at most meals (eggs, beans, yogurt, poultry, tofu)
• Fiber daily (fruit, oats, lentils, veggies) to help constipation
• Healthy fats (avocado, nuts, olive oil) for satiety
• Iron and calcium sources (talk to your provider about supplements if needed)

Move (if your provider says it’s okay)

For many uncomplicated pregnancies, expert guidance often recommends aiming for about 150 minutes/week of moderate activity
(think brisk walking, prenatal yoga, swimmingactivities where you can talk but not sing). If you’re dealing with pelvic pain, dizziness,
contractions, or medical complications, your provider can tailor advice to your situation.

Track patterns, not single weigh-ins

One day of “whoa, why did the scale jump?” can be fluid, constipation, salty food, or swelling. Your prenatal team looks at trends and overall health,
not a single number. If weight conversations stress you out, say soproviders can often adjust how weigh-ins are handled.

A Practical Third-Trimester Checklist

• Know your “go time” plan: who drives, where you go, who watches other kids/pets (if relevant).
• Pack a small bag: charger, comfy clothes, toiletries, snacks (check hospital rules), paperwork.
• Install the car seat early (or schedule an inspection if available in your area).
• Choose postpartum basics: pads, comfortable underwear, a water bottle, easy meals, support contacts.
• Write down questions for prenatal visits (labor signs, pain options, feeding plans, recovery).

Conclusion: The Goal Isn’t “Perfect”It’s “Supported and Safe”

The third trimester can be uncomfortable, weirdly emotional, and occasionally hilarious in the “why am I crying over a commercial about puppies?” way.
Weight gain and body changes are part of the physiology of building a baby and preparing for birth. Your best move is to focus on supportive habits,
keep your prenatal appointments, and speak up about symptomsespecially the ones that feel off.

You’re not “failing” because you’re tired, swollen, or eating crackers at midnight. You’re doing a complex biological project with no off button.
Be kind to yourself. And if anyone says, “Sleep now while you can,” you have permission to blink slowly and walk away.

Real-Life Third-Trimester Experiences (What People Commonly Report)

Everyone’s third trimester is different, but certain themes pop up again and againlike a playlist you didn’t ask for, but somehow know all the words to.
Many people describe the first weeks of the third trimester as a weird mix of “I can’t believe we’re almost there!” and “Wait, we still have HOW MANY weeks?”
The excitement ramps up, but so does the day-to-day reality of carrying extra weight, managing symptoms, and trying to function like a normal human.

A common experience is feeling physically capable but strategically limited. You can do things… you just can’t do them the same way.
Bending down becomes a negotiation. Rolling over in bed becomes a three-step maneuver with sound effects. Standing up from the couch may require a handrail,
a pep talk, and a brief intermission. Many people say they start planning life around practical questions like: “Is there a bathroom nearby?” and
“Can I sit down for this?”

With weight gain, lots of people report a mental shift. Early pregnancy weight changes can feel abstract, but third-trimester gain is often more noticeable
because it comes with other sensations: swelling, tighter skin, pressure on joints, and changes in posture. Some feel proud of their body’s work.
Others feel frustrated, self-conscious, or simply uncomfortable. Many feel all of those emotions in the same afternoonsometimes while eating a snack
they swore they didn’t want (and then absolutely did).

Another frequent report: sleep becomes unpredictable. People talk about waking up multiple times a nightsometimes for the bathroom, sometimes from heartburn,
sometimes because the baby is hosting a midnight dance recital. Some say pillows become prized possessions. Others develop strong opinions about side sleeping,
room temperature, and whether it should be illegal for partners to breathe loudly after 2 a.m.

Emotionally, many people describe the third trimester as a time when nesting kicks insometimes as focused productivity (“Let’s assemble the crib!”) and
sometimes as random urgency (“We must reorganize every drawer in the kitchen today or nothing will be okay”). It’s also common to feel more vulnerable:
anticipation about birth, concerns about recovery, and questions about what life will be like afterward. Many people find that talking through fears with a provider,
a partner, a friend, or a support group makes a huge difference.

And yeslots of people say the third trimester comes with moments of unexpected joy. Feeling the baby move, hearing a strong heartbeat at appointments,
washing tiny clothes, imagining who this new person will be. It can be tough and tender at the same time. If there’s one takeaway from shared experiences,
it’s this: the third trimester is not a performance. You don’t have to “win” it. You just have to get through it with support, good medical guidance,
and a little compassion for the fact that your body is doing something extraordinary.