You unclasp your bra at the end of the day and there they are again: red lines under your breasts, a sore spot where the wire pressed all afternoon, and cups that seem to fit a little less every week. Your breasts are tender, heavier and changing faster than you expected, and you are starting to wonder whether it is time to buy something new, or whether it is too early. If you are asking when to buy nursing bras, you are asking at exactly the right moment. The answer depends on your body more than the calendar, and for most women, a soft wireless nursing bra is the most comfortable place to start.

Why your breasts change so much, and why timing matters

Your breasts are one of the first places pregnancy shows. The NCT, the UK parenting charity, explains that pregnancy hormones cause the milk ducts to expand in preparation for breastfeeding, and that for some women, one of the earliest signs of pregnancy is breasts that feel larger and more tender. For many, that growth continues through pregnancy, and then changes again when milk comes in after birth.

That constant change is exactly why timing matters. Buy too early, and your bras may stop fitting before your baby arrives. Wait too long, and you may find yourself after birth with nothing comfortable to wear during those first busy days. According to the NCT, a bra bought from around 28 weeks of pregnancy should still fit after the birth, although some women find they need a larger cup size in the early months.

It is also completely normal for your size to change more than once. Some women need new bras early in pregnancy because their breasts grow quickly, and then again later. The NCT notes that people may buy early and then need to buy again. There is no failure in that. It is simply your body preparing to feed your baby. Many mothers find their size keeps shifting in the first weeks after birth, and then settles once feeding finds its rhythm, so a few flexible pieces are often a smarter start than a whole drawer of bras in one size.

And your feelings about these changes are valid too. Some women love their new curves, while others feel self-conscious or just uncomfortable. Whatever you feel, you deserve a bra that supports you gently rather than one you count the minutes to take off.

When to buy nursing bras, and how to choose the right fit

For most women, a good window is the third trimester, from around 28 weeks, as the NCT suggests. By then, much of the growth of pregnancy has happened, and a well-chosen bra has a good chance of carrying you into the first weeks of feeding. If your current bras already feel tight earlier than that, it is fine to buy sooner. Comfort is the real signal, and there is no reason to spend weeks squeezed into bras that leave marks just to wait for a certain date.

Start small. Two or three nursing bras are usually enough before birth, which also matches what the NHS suggests packing in your hospital bag. You can buy more later, once your milk supply settles and you know which styles you like. If possible, try a couple of different styles and sizes and keep the ones that feel best.

When you check the fit, think about room to change. Many women like to fasten a new bra on the loosest hook in late pregnancy, so there is space to tighten it after birth as the ribcage settles. The cups should hold your breasts fully without cutting in at the top or sides, and there should be a little space for the swelling that often comes when milk arrives. Stretchy, soft fabrics adapt better to these changes than rigid cups. The NCT also recommends breathable fabrics such as cotton, which can make a real difference when you are warm, leaking or feeding often.

Think about how you will use each bra, too. A soft, stretchy style you can sleep in, a slightly more supportive one for daytime, and a spare for laundry days cover most of what you will need in the early weeks. If you plan to pump, check that the style is easy to open fully or works with a pumping bra layered over it. Having a mix of styles means you can choose what feels best on a given day, rather than forcing one bra to do everything.

Look at how the bra opens, too. Clips or clasps that you can undo with one hand are a huge help when you are holding a hungry baby with the other. Some styles are designed to be worn day and night, which many women appreciate in the early weeks, when feeds are frequent and leaks can happen at any time.

Why a wireless nursing bra is the gentle choice

Underwire bras are not forbidden, and some women with larger breasts prefer the structure. But many women find that rigid wires press uncomfortably on breasts that are tender, growing and changing shape through the day. As breasts fill and empty around feeds, a wire that fit in the morning can dig in by the afternoon. That is why so many mothers choose wireless styles, at least for the first months.

A good wireless style supports you through soft, stretchy fabric, wide bands and comfortable straps rather than a rigid frame. It moves with your body as it changes, which means it is more forgiving if your size shifts a little from week to week. Many are also comfortable enough to sleep in, which can help keep breast pads in place at night. Vest styles, crossover styles and soft sling styles each offer a slightly different feel, so it is worth choosing the one that suits your shape and your day.

Fabric matters more than you might think. Breasts often feel warm while you are pregnant and feeding, and leaks are common in the early weeks. Soft cotton and breathable blends help keep skin comfortable and dry, especially if you wear breast pads underneath. Seamless designs can also be kinder to sensitive nipples, since there are no stitches or edges pressing where you are most tender. And because you will wash your bras often, choose styles that keep their shape after many trips through the laundry.

If you have larger breasts, look for wireless bras made with extended sizes, wider bands and firmer, supportive fabric. Wire-free does not have to mean unsupported. And whatever style you choose, the fit test is the same: at the end of a long day, you should barely notice you are wearing it.

When to call your doctor

Breasts change a lot during pregnancy and breastfeeding, and most changes are normal. Still, the NCT advises talking to a doctor or midwife about any unusual breast changes. Call your provider if you notice a new lump that does not go away, skin changes, or nipple discharge that is bloody. While breastfeeding, get help promptly if part of your breast becomes red, hot, swollen and painful, especially with a fever or flu-like feelings. A bra that is too tight can also leave painful pressure points, so if a style keeps hurting, stop wearing it.

Common questions

How many nursing bras do I need?

Two or three are usually enough to start, so you can wear one, wash one and have a spare. You can add more after birth, once you know your size and favorite styles.

Should I size up when buying nursing bras during pregnancy?

Many women choose a style with stretch and fasten it on the loosest hook, so it can adjust as your body changes after birth. The NCT notes that some women need a larger cup in the early months of feeding.

Can I sleep in a wireless nursing bra?

Many women do, especially in the early weeks when feeds are frequent and leaks are common. Choose a soft, stretchy style that does not feel tight when you lie down.

Your breasts are doing extraordinary work, before and after your baby arrives. Knowing when to buy nursing bras means listening to your body, choosing soft, flexible styles and leaving room for change. The right bra should feel like quiet support, not something you are waiting to take off.

If you are ready to find yours, the Wireless Nursing Bras collection at Pregfancy.com has soft, wire-free styles in sizes up to 3XL, including vest and crossover styles, one-handed clasp designs, sling styles with pads and plus-size options. They will not stop your body from changing, but many women find that a comfortable nursing bra makes every day of pregnancy and feeding feel a little lighter.

Explore the Wireless Nursing Bras collection at Pregfancy.com

This article is for educational purposes only and is not medical advice. Talk with your doctor, midwife or a lactation consultant about any breast changes or feeding concerns.