Ultrasounds: What Is EFBW and GMS?

Thanks for your question and congratulations on your pregnancy. During pregnancy, a number of ultrasounds and scans are carried out to monitor how the pregnancy is growing and the growth of your baby in the womb. Ultrasounds are painless and safe, so it's an ideal method of scanning for pregnancy.

It's standard practice for ultrasounds to be carried out at the stages of three months and five months into pregnancy. Many hospitals provide women with a printed copy of the scan to take home afterwards – often they very clearly show your baby, although other times they could be facing the wrong way, have a limb crossed or be obscuring the face somehow! It's a bit hit and miss when photographing babies in the womb like this, but it's a lovely memento to take home. At the bottom of the scan there are various printed letters and numbers, including EFW and GMS.

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Although it may seem like a slightly strange acronym, EFW actually stands for Estimated Fetal Weight – the current estimated weight of your baby. The second part, in your case 323 GMS, stands for the estimated weight – i.e. 323 grams.

The meaning of this acronym should have been explained to you at the scan (remember, if you are unsure about anything, it's always fine to ask – although it's easy to forget at the time and only think of things later on). The estimated weight is also often given out to mums, although it's usually given in the form of pounds and ounces rather than grams. Pounds and ounces is the form of measurement that babies are traditionally weighed in and it's what most people can understand in terms of baby weight. It's worth bearing in mind, though, that this is very much an estimate at this stage, as the actual weight can vary considerably. In fact, it can vary by about 25%.

Due to the variation in actual birth weight, not all hospitals do give out details of the estimated birth weight, which is why you may not have been told what EFW meant. During the next few months, your baby will be increasing in size and continuing to grow and develop in a variety of ways.

Good Luck With The Rest Of Your Pregnancy!

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The Next Step

Now that you have read through the advice above, you might want to put it into practice. Our Due Date Calculator lets you calculate your estimated due date and get week-by-week pregnancy guidance. Try it now →