Maternity Underwear Buying Guide: What to Look For

Quick answer

Buy maternity underwear that fits your current hip measurement, not your pre-pregnancy size, and prioritise a soft waistband that sits under or over the bump without digging in. Choose breathable bamboo-rich or microfibre fabric, and buy a small rotation rather than one perfect pair. If you are unsure, start with one size up from your usual brief and adjust as your shape changes.

Maternity underwear is not just regular underwear in a bigger size. Your hips, waist and bump change shape across pregnancy, and a waistband that felt fine at eight weeks can feel restrictive by thirty weeks. The right pair should stay put, breathe well and avoid pressure points.

This maternity underwear guide walks through the decisions that matter most: fit, fabric, waistband height, coverage and how many pairs you actually need. It also covers the trade-offs, because no single style suits every stage or every body.

Start with fit, not size labels

Size labels vary between brands, so treat them as a starting point rather than a rule. Measure your hips at the fullest point and compare that to the brand's size chart. If you are between sizes, size up for maternity underwear, because you will likely grow into it and a snug band is more uncomfortable than a slightly loose one.

Fit should feel supportive but never tight. The waistband should not leave red marks, roll down or press into your belly. If you can feel the elastic when you sit, it is too firm. Re-check your fit every four to six weeks, especially in the third trimester when your shape can change quickly.

• Measure hips, not your pre-pregnancy waist size.
• Size up if you are between sizes or in the third trimester.
• Test the fit while sitting, not just standing.

Choose fabric that breathes

Pregnancy can increase body heat and discharge, so breathability matters. Bamboo-rich and cotton-blend fabrics are popular because they feel soft and manage moisture well. Microfibre is another option: it feels smooth, dries quickly and works well under fitted clothing, though it can feel less airy than natural fibres.

Look for a cotton-lined gusset if you want extra breathability where it counts. Avoid heavy synthetic fabrics with no stretch if you tend to overheat. If you are prone to irritation, change your underwear daily and consider a fabric with a soft, seamless finish to reduce friction.

• Bamboo and cotton blends suit most pregnant bodies.
• Microfibre is smooth and quick-drying but less breathable.
• Prioritise a breathable gusset if you are prone to irritation.

Pick a waistband height that suits your stage

Under-bump waistbands sit below your belly and suit early pregnancy or anyone who dislikes pressure on the bump. Over-bump waistbands provide gentle support and stay put in later pregnancy, but they can feel warm in summer. High-waisted briefs offer a middle ground: they cover the lower belly without sitting high on the bump.

There is no single correct choice. If you are buying for the whole pregnancy, over-bump or high-waist styles usually last longer because they accommodate growth. If you are buying for the first trimester only, an under-bump style may feel more comfortable and can double as everyday underwear after birth.

• Under-bump: best for early pregnancy and warm weather.
• Over-bump: supportive and secure in later pregnancy.
• High-waist: a flexible middle option for most stages.

Decide how much coverage you want

Coverage is personal. Full briefs and high-cut styles offer more bottom coverage and can feel more secure, while bikini and g-string cuts suit anyone who prefers less fabric. For maternity, a high leg cut can be flattering and reduce rubbing, but check that the leg elastic is soft and does not dig in.

If you wear pads after birth, look for a brief with enough coverage to hold them in place. Postpartum underwear often overlaps with maternity styles, so a well-chosen pair can serve both stages. Just avoid anything with a tight leg opening, which can cause discomfort when you are sitting for long periods.

• Full coverage suits pads and postpartum use.
• High leg cuts reduce rubbing but check the elastic.
• Avoid tight leg openings if you sit for long stretches.

Build a small rotation, not a single pair

You will wear maternity underwear every day, and laundry rarely keeps up. A practical rotation is five to seven pairs: enough to cover wash cycles without overbuying. Multipacks are often better value and reduce decision fatigue, especially if you find a style you like.

Buy in two phases if your budget allows: a few pairs for early pregnancy and a few more when you reach the third trimester. This avoids buying everything before you know how your body changes. Keep the tags on until you have worn one pair for a full day.

• Five to seven pairs is a realistic minimum.
• Multipacks reduce cost per pair.
• Buy in phases to match your changing shape.

Decision rules for buying maternity underwear

• If you are in the first trimester: Choose an under-bump or high-waist brief in your current hip size. Avoid buying many pairs yet, because your shape will change. Buy two to three pairs to test fit before committing.
• If you are in the third trimester: Choose over-bump or high-waist styles with a soft, wide waistband. Size up if you are between sizes or feel any pressure when sitting. Prioritise comfort over a snug fit.
• If you plan to breastfeed: Consider a nursing bra with a detachable clip and support sling, such as the Wire Free Full Bust Maternity & Nursing Bra, so it works for pregnancy and after birth. A dual-purpose bra reduces what you need to buy.
• If you overheat easily: Choose bamboo-rich or cotton-blend fabric over heavy synthetics. Look for a breathable gusset and avoid thick, non-stretch waistbands. Breathability matters more than a smooth silhouette in hot weather.
• If you are unsure about size: Measure your hips and check the brand size chart. If you are between sizes, size up. A band extender can also add flexibility to bras. One size up is usually the safer choice in maternity underwear.

Product facts that help your decision

• Wire Free Full Bust Maternity & Nursing Bra: Made from breathable, super soft bamboo-rich fabric and knitted on seamless machinery, with a detachable nursing clip and an inside support sling. Bamboo-rich fabric and a seamless knit reduce pressure points, while the nursing clip and support sling make it useful beyond pregnancy if you plan to breastfeed.
• Full Bust Comfortable Wire Free Support Bra + Band Extender Set: Includes a 3x4 hook bra extender with four extra rows, offering 2-8cm of optional band extension. The extender lets you adjust band size as your ribcage expands, which can extend how long the bra fits without buying a new size.



• Curvy Invisible Lace Contour High Cut Brief: Features a classic high waistband, delicate lace detailing, plenty of bottom coverage and a high leg cut in microfibre fabric with light control. The high waist and full coverage suit pregnancy and postpartum, while the microfibre gives a smooth finish under clothing.

Who this maternity underwear guide is for

Best for

• Anyone buying maternity underwear for the first time and unsure where to start.
• Pregnant people who want comfortable maternity undies that work across trimesters.
• Shoppers looking for pregnancy underwear in Australia with practical fit advice.

Not for

• Anyone looking for a specific style review or brand comparison.
• People who need medical advice about pelvic pain or postpartum recovery.
• Shoppers who already know their exact size and preferred style.

Maternity underwear comes down to fit, fabric and waistband height. Measure your hips, size up when unsure, and choose breathable fabrics with a soft band that does not dig in. Build a small rotation and adjust as your body changes. If you want a starting point, the B Free maternity and nursing range covers wire-free support and high-waist briefs that work across pregnancy and beyond.