Anyone who has ever tried to dress an ever expanding belly will know that it’s not always an easy task. Your body is changing rapidly and comfort is becoming pretty much your one and only priority.

When I was pregnant with my first child, I remember sitting at my work desk googling ‘maternity fashion’ for advice on what I should be updating my wardrobe with. My heart sank as I realised that for a lot of people maternity fashion equaled hippo in a muumuu. And a very expensive muumuu at that.

But maternity fashion doesn't have to mean roughing it in the style stakes for nine months- nor does it mean approaching the bank for an increased credit card limit. It's far better to invest your money in some good quality key pieces that will see you through the duration of your pregnancy (and beyond). We spoke with some of the best maternity fashion gurus about what you need (and what you don't need) for your nine months up the duff.

Cath, style expert at Baby, Bump and Beyond Maternity who says, "Many of our customers feel a bit lost when it comes to their pregnancy style and what they need to buy - our best advice is to consider the pieces in your normal wardrobe that you wear the most. These are the pieces you want to either make work during pregnancy, or find a substitute for. Maintaining your own sense of style can be an important part of continuing to feel like 'you' when your body - and your life - are changing".

Here's our picks of the essential maternity wardrobe items for every mum-to-be.

1. Maternity jeans or jeggings.

Cath says, "Even if you've never won leggings before, they are well worth considering during pregnancy. That bit of extra stretch, and the more flexible sizing make it much easier to find a pair that fit well and look good".

Keep in mind that you won't be jumping back into your pre-bub jeans straight away, so comfy maternity jeans will be your friend for some time after your bump turns into a baby. It's well worth investing in something you'll love.

In terms of sizing, Cath says to stick with your usual pre-pregnancy size because maternity wear designers have allowed for extra growth in the clothes. Providing you stay within the 'normal' limits of pregnancy weight gain, the clothes will see you right through to the end. The only exception she says is those lucky enough to be carrying more than one bundle, who may wish to go up a size for comfort.

Go for something in a classic blue wash or black (my fav) which will work with pretty much everything else in your wardrobe.

After opting for lesser known pregnancy jeans during my last few pregnancies, I was introduced to the Isla leggings by Ripe maternity and from day one I've been in love. In fact, they are pretty much my go to maternity jean. The fit is skinny which means they work for both day and night but with elastic panels in the waistband, I'm comfortable no matter what I'm doing.

2. Leggings.

Leggings are another one of those basics you'll wear time and time again throughout your pregnancy.

Perfect to throw on under long tops or dresses or just to pop on with sneakers for a casual weekend walk you can find maternity leggings in a range of different materials. Amanda from GlowMama Maternity says, "Go for versatility and comfort.  Invest in some good quality basics that you can mix, match and accessorise to suit each occasion. Eco fabrics like Bamboo and Organic Cotton feel amazing next to the skin and will keep you cool."

This pregnancy, I've been lucky (?!) enough to suffer from SDP, which has caused some pretty serious discomfort. My OB recommended I try compression leggings which are specially designed to support the bump and encourage adequate blood flow throughout the legs and pelvis during pregnancy. They're also great for preventing varicose veins (winning!).  I'm using these ones from SRC Compression and have absolutely noticed a difference in swelling and discomfort. Plus, the best bit is that they look just like regular leggings.

3. Tube dress.

A tube dress is another item that will see you through your entire pregnancy. Not only are the super comfy, but they show off your growing curves beautifully. Pre-pregnancy, I never would have felt confident enough to wear a tight fitted dress but I found that dressing in floaty, heavy layers when pregnant only added bulk, making me feel dowdy.

Amanda says the key is to focus on your best assets and pick a dress which accents them. Got great legs? Choose a style with a shorter skirt. If your cleavage is rockin' select a lower cut tank with a longer skirt to draw attention upwards.

I love this one by Bamboo Body and by choosing a colour like classic black you've got yourself a multi-use item that can take you from day to night with a simple show change and some accessories. Just like before bub, an LBD is your best friend.

4. Maxi dress.

A maxi dress is great daytime wear during the warmer months and in between seasons. There are no restrictive areas and by adding a jacket or cardigan you can tailor the look to suit the weather.

I love this one from Seraphine maternity. It's something I'd go straight to in a 'normal' shop and is so light and comfy. It's been a bit cold to wear it alone but with a cropped denim jacket and long necklace it's great for casual weekends.

5. Maternity tanks/t-shirts/long sleeve tops.

Long-line tanks will become your best friend. As your bump grows you'll need the extra length to cover up the tum and having a selection of basic colours will mean that you can adapt items from your pre-pregnancy wardrobe.

Most maternity tanks have ruching down the sides which means they will take you from beginning to (make it) end of your pregnancy without needing to purchase larger sizing.

You don't need a lot but having say, three maternity t-shirts (or long sleeve tops depending on the season) will again mean that you can keep your outfit simple and jazz it up with accessories. I have some plain white, black and grey maternity t-shirts on high rotation which accommodate the growing bump perfectly. My current favourite are from Bamboo Body (super soft!) and Sussan.

6. Stretchy skirts.

This is one item that doesn't necessarily need to come from a maternity shop, although they often have a great range.

Stretchy skirts which can be pulled up under the bump, or comfortably worn underneath are great for all seasons. Grab yourself some in some patterns or colours and wear them with leggings and boots in the colder weather and tanks with flats when it's warm.

I'm currently in love with one from Seed and have worn it for both day and nighttime events.

Finally, says Amanda, you should invest in one item that you love. "Have a go to item in your wardrobe that makes you feel amazing on those days you feel a little flat and 'over it'.  You deserve it!"

What do you think is the most essential piece of maternity fashion?