At 30 weeks pregnant, your baby is about the size of a cabbage, and the brain is maturing and growing rapidly — developed enough now to control body temperature independently. Ten weeks (give or take) to go, and growth is picking up speed heading toward your due date.

If your dates feel confusing, remember that gestational age counts from the first day of your last period (LMP), not from conception — so "30 weeks pregnant" usually means about 28 weeks since ovulation. For the full timeline, see our pregnancy week-by-week guide, or find out exactly how your due date is calculated. If you're picking up from last week, catch up on 29 weeks pregnant first.

Diagram comparing a cabbage to a 30 week fetus, showing the brain maturing and growing rapidly — At 30 weeks, your baby is about the size of a cabbage, with the brain maturing and growing rapidly.

Key takeaways

Baby is about the size of a cabbage (roughly 39.9 cm, head to heel) and weighs around 1,319 grams.
The brain is maturing and growing rapidly, developed enough to help control body temperature.
About 10 weeks remain until a typical full-term due date.

What "30 Weeks Pregnant" Actually Means

Using standard gestational dating, week 30 starts about 28 weeks after ovulation, placing you solidly in the third trimester. In fetal-age terms (counting from conception rather than your last period), this is closer to "28 weeks post-conception."

With roughly 10 weeks left until a typical 40-week due date, this is often when pregnancy starts to feel like it's entering its final, more physically demanding chapter.

Baby Size at 30 Weeks

At 30 weeks, your baby is about the size of a cabbage — roughly 39.9 centimeters long, measured head to heel, and weighing around 1,319 grams. (Source: Baby Your Baby, Utah Department of Health)

A Rapidly Maturing Brain

This week, your baby's brain is maturing and growing rapidly, and has developed enough to help control body temperature independently. (Source: Cleveland Clinic) This is a meaningful step, since temperature regulation is one of the many systems that has to be reasonably functional for a baby to adapt to life outside the womb.

Brain tissue is also developing more grooves and folds around this stage, increasing surface area to accommodate the rapidly growing volume of brain matter — a pattern that will continue through the rest of pregnancy and well into early childhood. Alongside this, your baby's eyes can open and close, and there's evidence some light may be perceptible through the uterine wall and abdominal tissue, even though the environment inside stays quite dim.

Diagram showing a 30 week fetus brain developing grooves and folds as it matures rapidly — At 30 weeks, the brain is developing grooves and folds as it matures rapidly, supporting functions like body temperature control.

What You Might Notice at 30 Weeks Pregnant

Week 30 tends to bring a mix of a growing belly and the physical demands of late pregnancy. Here's what commonly shows up:

Increased fatigue, as your body continues supporting rapid third-trimester growth.

Shortness of breath, as the uterus keeps pressing up against the diaphragm.

Backaches, as your center of gravity continues shifting forward.

Swelling in the feet and ankles, especially by the end of the day.

Trouble sleeping, as the belly grows large enough to limit comfortable positions.

Forgetfulness, sometimes called "pregnancy brain," which some people notice more in the third trimester.

Braxton Hicks contractions, appearing as occasional, painless tightening in the belly.

It's also completely normal to have few or no symptoms yet. Symptom timing and intensity vary widely from person to person and even between pregnancies for the same person.

What's Happening in Your Body

The brain matures and grows rapidly, developing more grooves and folds.
Body temperature control is developed enough to function independently.
Eyes can open and close, with possible light perception through the abdominal wall.
About 10 weeks remain until a typical full-term due date.
Fatigue and shortness of breath often increase as your body supports rapid growth.

Tips for Week 30

Rest when you can, and don't hesitate to ask for help as fatigue increases.

Sit and stand up slowly if shortness of breath or lightheadedness shows up.

Keep a small notepad or app for reminders if forgetfulness is frustrating you — it's common and temporary.

Elevate your feet in the evening if mild swelling shows up.

Start finalizing your hospital bag or birth plan, if you haven't already, since the final stretch tends to move quickly.

Keep taking your prenatal vitamin — steady nutrition continues to matter through the rest of pregnancy.

Tips for Partners

Help with reminders and scheduling if forgetfulness is showing up — a shared calendar can help a lot.
Take on more of the physical chores as fatigue and shortness of breath increase.
Start finalizing hospital bag or birth plan logistics together.
Offer a foot rub or help propping up swollen feet in the evening.

FAQ

How big is my baby at 30 weeks pregnant? About the size of a cabbage — roughly 39.9 centimeters long, measured head to heel, and weighing around 1,319 grams.

Can my baby control their own body temperature at 30 weeks? The brain has developed enough to help control body temperature independently, though this system continues maturing through the rest of pregnancy.

Why is my baby's brain developing folds and grooves? Folding increases the brain's surface area to accommodate its rapidly growing volume — a pattern that continues well into early childhood after birth.

Can my baby see light at 30 weeks? Eyes can open and close, and there's some evidence that light may be perceptible through the uterine wall and abdominal tissue, though the environment inside stays quite dim.

What symptoms are normal at 30 weeks pregnant? Fatigue, shortness of breath, backaches, swelling, trouble sleeping, forgetfulness, and Braxton Hicks contractions are all common at this stage.

How many weeks do I have left at 30 weeks pregnant? About 10 weeks remain until a typical 40-week due date, though every pregnancy's timeline is a little different.

When is my next prenatal appointment likely to be? Many providers continue with appointments every two weeks around this stage of the third trimester, then weekly closer to 36 weeks.

Pregnancy Checklist at Week 30

Keep taking a prenatal vitamin daily
Rest when you can as fatigue increases
Use reminders or a notepad if forgetfulness is frustrating you
Elevate your feet if mild swelling shows up
Start finalizing your hospital bag or birth plan
Sit and stand up slowly if shortness of breath occurs
Note any severe cramping, heavy bleeding, or reduced movement and call your provider if it occurs

Related guides

29 Weeks Pregnant: Symptoms, Baby Size & What to Expect — what happened the week before, as space got tighter in the amniotic sac
Pregnancy Week by Week: A Complete Guide — see what happens in every week and trimester, from implantation to full term
How Is Your Due Date Actually Calculated? — the exact formula behind your due date, plus a free calculator

Week 30 brings rapid brain development, with roughly 10 weeks left until a typical due date and the home stretch of pregnancy well underway.