More 4 Mums offers an affordable range of nursing bras available online.  We have produced this guide to Nursing Bra Fitting to help you choose the correct size and style. 

When is the best time to buy a nursing bra?

The ideal time to buy your nursing bras is in the final weeks of your pregnancy. This way, you can have a couple with you in the first few hectic days at home with your baby.

 What happens to my sizing after delivery?

Most women will find that their upper body will slim down after they have given birth, so you should make sure that you have the ability to tighten the band of the bra in the future. So, if you are buying a bra in the last weeks of pregnancy, you should choose a bra that you can wear on the last set of hooks, or one which is stretchy around your rib cage. You should make sure that your bra is snug at this stage, but it should not ride up your back. If your milk has not yet come in (this typically happens 3-5 days after you have given birth), try to allow some extra room in the cups for this to happen, or have hooks that accommodate your changing breast size. If you find that once your milk has come in, you need a larger size, you may be able to switch back to the smaller size after your milk supply is regulated (this is usually about 3 months after giving birth).

black seamless nursing bra

What should I look for in a Nursing Bra?

Nursing bras are not underwired and the cups undo one-handed for easy feeding.  Some bras are designed to be pulled aside depending upon the style.  You should also look for wider, more supportive shoulder straps, strong side panels, a very flexible, soft inner cotton ‘sling’ and a stretchy fabric with a high cotton content which will be breathable and help keep you cool. Your breasts will change size when the milk comes in (approximately 48 hours after the birth) and will continue to change day and night until you’ve established a proper routine. It may be best to leave buying bras until a week before your due date – or later – for a more accurate fit. The reason that breast-feeding consultants and midwives do not recommend under-wired bras is that they can cause pressure on your milk ducts which may lead to mastitis; infection of the breast tissue.


To work out your band size (the number part) take a tape measure and place it around your body so that it lies flat just under your bust. Take this measurement in inches, rounding up if the circumference comes out as an uneven number (i.e. if the actual measurement is 37″ your correct band size would be ’38’). You now have your band size. To work out your cup size you should take the tape measure and place it around the widest part of your bust whilst wearing a well fitted, unpadded bra. Again, take this measurement in inches. You will then need to work out the difference between this measurement and your band size to find out your cup size. Every inch of difference between these two measurements is equivalent to an increase of one cup size.

e.g. Say your band size is 36 inches and your bust measurement is 39 inches, the difference between the two is 3 inches. Using the table below you can see that this is equivalent to a C cup size, so your overall bra size would be 36C.

Bust measurementCup Size
1″ – 2″A
2″ – 2 1/2″B
2 1/2″ – 3 1/2″C
3 1/2″ – 4 1/2″D
4 1/2″ – 5″E
5″ – 6″F
6″ – 7″G

Nursing Bra Fitting

Ensure the nursing bra is fitted on its loosest fitting to allow for the back to reduce in size, and for wash and wear. This will ensure the bra can be tightened to make it firm, so that it is supporting the breasts.  Ensure there is space in the top of the cup for when the milk ‘comes in’. Simply slide your hand under the fabric on the top of the cup to check if there is space for the fabric to be pushed outwards. Ensure the nursing bra is fitted firmly on its tightest fitting so that there is space to grow into as the rib cage expands.