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Predicting Your Nursing Bra Size - A Guide for First Time Moms

First-time moms have a lot to deal with as they prepare to receive their new bundles of joy and after delivery. Furniture needs to be moved. Nursery rooms have to be stocked with an array of items ranging from crib to nightlight. Oh!.. and what about that college fund! Besides, many of our boss mommas want to be ahead of the curve and get their nursing bras inventory stocked up as well.

However, new moms often find themselves confused by their changing bodies throughout pregnancy, lost in a dilemma to predict their respective perfect nursing bra sizes. Are you in such confusion? Don’t worry. Here’s some guidance.

Word of Caution: Everything is changing 

As you adjust your budget to factor in the needs of the expected little one and stock your house with the necessary items, your body also changes day by day to accommodate the new attached life safely. Besides experiencing a significant weight gain and some weird cravings, your breasts will look and feel very different from how they were before the pregnancy. They might be itchy as a result of skin stretching as they grow.

And they will begin to grow from approximately the sixth, seventh or eighth week of your pregnancy and continue getting bigger up to the time you’ll deliver or start to breastfeed.

So how big are yours going to grow? And how will they change over the next months?

Most first time mothers experience a breast growth of one cup size or two by the time they are starting to nurse their babies. For that reason, with time during pregnancy, your regular bras will be too small to hold your grown breasts.

At such time, maternity bras come in handy, else you’ll keep on buying different sizes to keep abreast with your regular changes. Maternity bras feature an extra stretch in the cup to enable them to grow with the changing shapes of pregnant mothers.

Read our explainer on Maternity Bras>>

Eyeballing a Fit: Step by Step Process

As earlier mentioned, mostly, the breasts of a first time mum grow by one, two or three cup sizes from the first trimester or early second trimester to the time a mother starts to breastfeed. The band size also grows by roughly one inch.

Therefore, if you are within the pregnancy period, the nursing bra that might fit you well the time you’ll be starting to breastfeed will be a band size and about one to three cup size larger. As such, you need to know the exact measurements of your current bra to predict the proper nursing bra size.

Here are the steps of measuring yourself to know your current bra size:

1) Get your band measurement

Get a measuring tape, bring it around your back and let it pass under your armpits and above the breasts. Record the measurement. If you get a fractional number, round it off to the nearest whole number. That’s your band size.

2) Establish your cup size

From the centre of one breast, run the measuring tape across the back and to the centre of the second breast. Record the measurement and round it off to the nearest full number if it isn’t.

Then, subtract your band size figure from the value you got here. The difference is your cup size. Bra cup sizes are represented by letters A, B, C, D, DD/E, DDD/F, G, H, I, J, K, L and M. The letters represent cup sizes measuring 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 13 inches, respectively.

Therefore, if your band measurement and bra cup size are 37 and 5, respectively, your current bra size is 37DD or 37E. Once you have this information, you can have a good foundation for getting a decent prediction of the nursing bras you should get

3) Estimate your nursing bra size

We’ve seen that your band size is likely to grow by an inch and the cup size by one, two or three inches from your first trimester to after delivery. So, after delivery, your band size might be 38 while the cup size could be 6, 7, or 8. As such, your best fitting nursing bra size could be 38DD, 38F, 38G or 38H.

What to Expect

Although these projected changes apply to most first time mothers, others have different experiences. For some, their band sizes get smaller and cup sizes bigger after delivery while others say that their boobs maintained the same size from their very last days of the last trimester to after delivery. Else, you might need a bra that’s 4 or 5 cup size larger than your regular bra. So do not feel uneasy if yours don’t grow as projected above.

Maternity bras come in a variety of sizes and shapes. They are built for maximum flexibility and comfort as you go through the breastfeeding process. We at MORI BAY worked hard to get the best possible maternity bras for you and your loved ones. 

Shop our best-selling maternity bras here >>


In the midst of the remarkable changes in your body and the busy journey as you prepare for the soon-to-arrive baby, you can buy the appropriate nursing bras in advance. Simply follow the above size prediction procedure to minimize the chances of your purchased nursing bras being too small or too large for you.



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