FREE SHIPPING WHEN YOU SPEND OVER $99

How Many Bra Sizes Do You Go Up When Pregnant?


Womene Blog Mar 2, 2025 · 12 min read

Introduction: Embracing the Shift in Body and Mind

Pregnancy is a thrilling ride of transformation—physically, mentally, and emotionally. For most expectant parents, the very first sign that big changes are on the horizon is a sudden shift in breast size and sensitivity. It can feel like you've entered a whole new dimension where your favorite bras no longer fit, your bra band digs in, and your cups can't seem to contain the fullness that arrived overnight. So, how many bra sizes should you anticipate going up when you're pregnant?

Though the answer isn't one-size-fits-all, most people see at least one or two cup-size increases by the third trimester. Some might notice more dramatic jumps, while others only experience a mild change. But the fact remains: pregnancy hormones are fully in charge here, preparing your body for breastfeeding by increasing blood flow and stimulating glandular tissue. If you're finding it challenging to figure out which bra to wear—or how to stay comfortable—this guide is for you.

In this blog series, we'll dive into the nuances of breast growth during pregnancy and share insights into sizing, bra types, and comfort tips. Throughout, you'll spot handy resources to keep you fully informed. By the end, you'll know exactly what's going on with your body and how to adapt your undergarment collection to keep pace with each stage of pregnancy.


Pregnancy breast changes diagram

Why Do Breasts Grow During Pregnancy?

The simplest explanation for pregnancy-related breast growth is hormones—lots of them. Estrogen, progesterone, prolactin, and other hormones ramp up production to get your breasts ready for feeding a newborn. But there's more to it than meets the eye. As explained by WebMD's resource on pregnancy bras, these hormonal surges kick-start a process that not only makes your chest bigger but also changes its shape, density, and even sensitivity.

The Early Changes and Their Impact

Many individuals experience breast tenderness or soreness even before a pregnancy test comes back positive. That familiar "heavy feeling" arrives in the first trimester, alongside swelling that can have you searching for a more forgiving bra band. Some folks may jump a whole cup size in those early weeks, while others just notice a slight snugness. By the middle of the second trimester, the growth might feel more dramatic, prompting many to switch to a supportive maternity bra.

Surging Hormones and Tissue Development

Digging a little deeper, you'll learn that estrogen and progesterone are behind the scenes, stimulating the milk ducts and glandular tissues. The end goal? To make sure your body is geared up to feed your baby. This may be your body's all-hands-on-deck approach, which explains the dramatic difference you see in your breast size. On top of that, increased blood flow to the area also contributes to the feeling of fullness.


Different types of maternity bras

Understanding Maternity and Nursing Bras

Before you raid your local lingerie store, it helps to know there's a difference between typical maternity bras and nursing bras—even if they sometimes serve similar purposes. Maternity bras are designed to offer extra comfort and accommodate your changing shape, whereas nursing bras go a step further by including front-access or drop-down cups for breastfeeding.

Take a look at this piece on Supportive Nursing Bras for Large Breasts for some handy tips on finding the right level of support and comfort, especially if you're already blessed in the bust department. During pregnancy, you might opt for a mix of wire-free maternity bras and classic underwire styles, depending on your personal comfort zone.

But do you need a nursing bra immediately? That's a question many soon-to-be parents ask. Some prefer to hold off until they're closer to the third trimester or until the baby has arrived, so they can be certain of their postpartum bra size. Others snap one up early for maximum comfort and functionality—especially if their breasts are growing faster than expected.


The Bra Sizing Puzzle: Finding Your Perfect Fit

As pregnancy progresses, many people find themselves caught off-guard by just how quickly their bra size can shift. One week everything feels fine; the next, there's a suspicious bulge over the cup edge and a band that's too tight. This can be frustrating—especially if you've invested in fancy lingerie that suddenly doesn't work anymore. But while it's inconvenient, it's also a completely normal part of the pregnancy journey. Below, we break down the process for measuring your new size, outline why you may need multiple fittings, and explore the average number of sizes you might expect to gain.


Steps to Determine Your New Bra Size

It's a good idea to start measuring for a new bra size as soon as you sense discomfort in your current one. You don't want your bra to feel more like a medieval corset than a supportive undergarment. According to some maternity fit experts, monthly measurements can be helpful, especially if you notice a rapid change in cup or band size. Even if you're only going up in half increments, the cumulative effect over a few weeks can be huge.

Measuring the Band

  1. Get the Right Tools: Grab a soft measuring tape, the same kind used for sewing. Avoid using a rigid tape measure, which can give you an inaccurate reading.
  2. Position the Tape: Wrap the tape around your ribcage, directly under your breasts where the bra band normally sits. Try to keep it parallel to the floor.
  3. Check Your Comfort Level: You want it snug—but not suffocating. Take note of the measurement in inches. In most bra sizing systems, you'll add a small number (like four or five) to convert to your band size. However, different countries and brands may follow varying guidelines, so a professional fitting can come in handy if you're feeling stumped.

Measuring the Bust

  1. Locate the Fullest Part: Usually, this is where your nipples sit. Wrap the measuring tape gently around your breasts, making sure it's level all around.
  2. Take a Breath: Don't hold your breath. Stand naturally—shoulders relaxed, arms down by your side.
  3. Difference Equals Cup Size: Subtract your band measurement from this bust measurement. The difference often indicates your cup size. For example, a one-inch difference can align with an A cup, two inches with a B, three inches with a C, and so forth—but that's a rough guide, and again, brand variations exist.

When to Switch to a Maternity Bra

Many people begin to crave the comfort of a specialized maternity bra sometime in the second trimester. If your pre-pregnancy bras are starting to leave marks on your skin or if the underwire is digging into your sides, that's a clear signal you might need something more accommodating. Another telltale sign? You start living in sports bras or bralettes just to avoid pinching and prodding.

When your regular bras start feeling like medieval torture devices, it's time to invest in maternity options designed for your changing body.

The Flexibility Factor

A standard bra often won't grow with you. Maternity bras, on the other hand, typically have wider bands with multiple hooks for easy adjustment, along with more forgiving cup materials. As this guide on maternity and nursing bras points out, designs made specifically for pregnancy can adapt to your shape, offering a better balance of support and comfort.

Support vs. Compression

While sports bras might seem like a comfy alternative, they're designed for compression, which is perfect for workouts but not necessarily ideal for day-long wear—especially if your breasts are sore or experiencing massive growth spurts. Maternity bras are built to lift and separate, distributing weight more evenly. This helps reduce back pain and keeps your posture in check.


How Many Sizes Should You Actually Go Up?

Most experts agree that jumping at least one or two cup sizes is common, but there's no universal number that applies to everyone. Some pregnant individuals may see a modest increase of half a cup or one full size, while others could jump three or four sizes. Genetics, weight fluctuations, and hormonal changes all play a role in determining how much your breasts grow.

Different Body Types, Different Outcomes

  • Petite Frames
    Those with naturally smaller ribcages might feel bra changes more intensely because even a slight increase in bust circumference can cause a bra to fit poorly. For petite frames, switching band sizes can be as important as adjusting cup sizes.
  • Plus-Size Figures
    For those starting with larger band sizes or cup sizes, you may notice that your breasts feel heavier as pregnancy progresses. Support becomes your best friend, and you might find it beneficial to invest in bras that include an inner sling or reinforced cups.

Timing Matters

Some people notice significant changes early in pregnancy, while others don't see a dramatic shift until closer to their due date. It's not unusual for cup sizes to continue shifting after birth when milk production fully sets in. A 2021 study on lactation physiology, published in a peer-reviewed article, highlights that postpartum breast size changes can be unpredictable—even between pregnancies. So, it's wise to be prepared for variability.


Woman being measured for a maternity bra

Multiple Fittings May Be Necessary

Pregnancy is a dynamic process; your body is evolving, and that includes your breasts. What fits perfectly in your second trimester may not hold up in the third. Multiple fittings—either professionally done or at-home measurements—throughout your pregnancy can help you stay comfortable and well-supported.

Keep an Eye on Comfort

Your bra should feel like it's holding you in place without cutting off your circulation. If you start noticing red marks or experiencing discomfort around the straps and band, it's usually a sign you need a refitting. Don't ignore those subtle cues—your body is speaking up for a reason.

Budgeting for Bras

Some people bulk at purchasing multiple sizes of bras, but consider it an investment in your well-being. Having two or three well-fitting options can make a world of difference in your daily comfort. You might also consider convertible bras that transition into nursing styles, giving you more mileage out of a single purchase.


Handling Rapid Breast Changes

Just as you've gotten used to one size, your belly seems to pop out more—and your cup size follows suit. While no two pregnancies look exactly the same, try to anticipate these jumps. Keep a comfortable, stretchy bra on standby. If you love to lounge, a maternity-friendly bra or wire-free option might become your best friend.

Monitoring Breast Health

As your bust grows, it's vital to stay aware of any discomfort, discoloration, or lumps. While most lumps during pregnancy are benign and related to milk production, it's always smart to consult a healthcare professional if something seems off. Remember, a well-fitting bra not only offers support but can also help you notice any unusual changes more quickly since you're not battling ill-fitting cups or wires.


Practical Tips for Bra Shopping During Pregnancy

As you navigate the world of maternity wear, finding the perfect bra can feel overwhelming. The market is flooded with options, and not all bras are created equal. This final section will provide you with actionable tips for shopping, choosing the best materials, and preparing for postpartum needs.


What to Look for in a Pregnancy Bra

Shopping for bras while pregnant requires a shift in priorities. Instead of focusing on aesthetics alone, comfort and functionality take center stage. Here's what to look for:

Adjustable Bands

Your ribcage expands as your pregnancy progresses, so choose bras with wide, adjustable bands and multiple hooks. These features will allow you to make gradual adjustments as your body changes, giving you a more precise fit.

Stretchable Cups

Opt for bras made with stretchable fabrics like spandex or elastane. These materials provide room for growth without compromising support. Stretchable cups are particularly helpful as your breast size may fluctuate daily.

Wide Straps and Supportive Design

Pregnancy bras should feature wider straps and a supportive structure to distribute weight evenly. This helps reduce shoulder strain and back pain, especially during the later stages of pregnancy.


Best Materials for Comfort and Breathability

The fabric of your bra plays a significant role in comfort, especially during pregnancy when skin can be more sensitive. Avoid synthetic materials that may trap heat or cause irritation.

Cotton for Breathability

Cotton is a popular choice for maternity bras because it's breathable, soft, and hypoallergenic. It's perfect for everyday wear, especially in warmer climates or during the summer months.

Bamboo for Sustainability

For those looking for sustainable options, bamboo bras are an excellent choice. Bamboo fabric is naturally antimicrobial, moisture-wicking, and incredibly soft, making it ideal for sensitive skin. Check out this guide to supportive nursing bras for additional eco-friendly recommendations.

Blends for Flexibility

A blend of cotton and spandex can provide both comfort and stretch. This combination ensures your bra grows with you, maintaining support throughout your pregnancy.


Preparing for Postpartum Changes

Your bra needs won't stop changing after pregnancy. Once your baby arrives, breastfeeding and postpartum recovery bring a whole new set of challenges. Planning ahead can help make this transition smoother.

Nursing Bras: A Must-Have

Nursing bras are designed to make breastfeeding easier while providing the support you need. Look for options with drop-down cups or front-closing panels for easy access. According to the National Childbirth Trust's guide, nursing bras with stretchy, supportive fabrics are perfect for fluctuating milk supply.

Sleep Bras for Nighttime Comfort

During the early postpartum days, you may find that wearing a bra at night is necessary for comfort and support, especially if you're using nursing pads. Sleep bras are soft, wireless, and designed for extended wear.

Managing Engorgement

Postpartum breast engorgement can be uncomfortable. A well-fitting bra that isn't too tight can help reduce discomfort while supporting your breasts. Avoid underwire bras during this period, as they can put pressure on milk ducts and increase the risk of clogged ducts or mastitis.


The Importance of Regular Fittings

Even after your pregnancy and breastfeeding journey, your breast size and shape may not return to their pre-pregnancy state. Scheduling regular fittings ensures that you're always wearing the right size. Ill-fitting bras can lead to poor posture, back pain, and even skin irritation, so don't underestimate the value of professional guidance.


Budget-Friendly Tips for Pregnancy Bras

Maternity bras can be an investment, but you don't have to break the bank to find good options. Here are a few budget-friendly tips:

Buy in Phases

Instead of purchasing a full wardrobe of maternity bras upfront, buy them as your size changes. Start with one or two bras in your first trimester, and gradually add more as needed.

Multi-Purpose Bras

Choose bras that transition seamlessly from pregnancy to postpartum. Convertible nursing bras, for instance, can save you money while providing the versatility you need.

Sales and Discounts

Keep an eye out for sales or online discounts on maternity wear. Many retailers offer bundle deals that can help you save while stocking up.


Making the Most of Your Maternity Bras

Once you've invested in maternity bras, taking care of them properly will help them last throughout your pregnancy and beyond. Hand-washing is the gentlest method, but if you prefer machine washing, use a lingerie bag and a gentle detergent to avoid damage.


When to Retire Your Maternity Bras

As your postpartum journey progresses, you may find that your maternity bras no longer fit or serve your needs. This is a natural part of the process. Consider transitioning to everyday bras that prioritise comfort and support, reflecting your post-pregnancy lifestyle.


Final Thoughts: Embrace the Journey

Pregnancy is a time of profound change, and your breasts are no exception. While figuring out how many bra sizes to go up when pregnant can feel like a guessing game, the key is to stay flexible and listen to your body. Invest in high-quality, supportive bras that prioritise comfort, and don't hesitate to adjust your wardrobe as needed.

Remember, your body is doing incredible things—and your maternity bras are just one small way to support yourself during this transformative time. For more tips on finding the perfect bra, check out this comprehensive guide.