top of page
  • Writer's pictureJen Curtis


This is a topic that’s been bugging me a lot lately. Like most women who are pregnant for the first time, I have been religiously devouring books and articles and blogs about pregnancy. Although my training has centred on physical activity during this time and not the pregnancy itself, I still know a fair bit about anatomy and physiology during this time of life – and it infuriates me when details are left out of some crappy blog or half-arsed book.

“Weight gain during pregnancy” is touched on a lot – and it’s almost always concluded with a variant on the following theme: “it’s normal” “try to love your body anyway, it’s doing an amazing thing” “try not to worry about the weight gain”.

Do we even need to discuss this?

Now, firstly I want to say that some people might think that it's not necessary to discuss fat gain during pregnancy – you might feel that we only need to revel in the glory of our bodies creating life and not even worry about issues such as fat gain. You might feel like it's a totally pointless topic and that I am just contributing to body image issues by even discussing it. But from my experience working with pregnant and postpartum women, I know that it's something that lots of women worry about, but they are not "allowed" to discuss it, or it is simply dismissed by literally everyone. It doesn't usually help to silence someone who is concerned about an issue, however trivial it may seem to you. It usually helps to talk about it, share the experience with others and UNDERSTAND it.

So this blog post is for those women, those that want to understand what's really going on and what the WEIGHT gain is really all about.


As a trainer, when people talk about wanting to lose weight, we are encouraged to talk to them about losing FAT. To talk about fat-loss and fat-gain. If someone weighs 100kg and is 40% fat – there’s still a hell of a lot of mass there that ISN’T fat – there’s water and muscle and bones and skin and organs… we don’t want to lose any of that weight. Women are often obsessed with the WEIGHT on the scale and want it to go down no matter what, but they aren’t paying any attention to, or measuring in any way how much of that is FAT. It is critical if we want to keep our metabolism up and stay strong and achieve long-term fat-loss.

It’s a similar story with pregnancy. Yes, you are going to gain weight, and yes it is normal. It is also very disconcerting if you’ve watched your weight for a long time to see it creep up on the scales.

But most books, when they address it in the way that I described above, make it sound like you have to deal with a whole lot of FAT gain – and this isn’t necessarily so – there is a whole lot of matter being made by your body at this time, and fat isn’t necessarily a large part of it (although it will be for some women).

Over the course of a normal pregnancy, you are likely to add weight in the following ways:


3-4 kg

This is no surprise to people

Amniotic fluid

0.5 kg


1 kg

Yes, 1kg, just uterus, NOT it's contents. The uterus of a woman who has never had a baby weighs approximately 100g. During pregnancy, it undergoes MASSIVE growth to accommodate the baby (it doesn't just stretch.) By the end of pregnancy it weighs around 1.1kg


1-2 kg

The average woman has around 4 litres of blood before pregnancy. At the beginning of pregnancy, her blood vessels dilate and her body has to produce more blood to fill the space (a problem called "underfill", which I will address in detail in another post). The result is a massive 40% increase in the total volume of blood in the woman's body. That's sometimes as much as 2 litres, or 2 kilos - just of blood! This helps supply the foetus with nutrients and oxygen all the time, dissipate heat and gives her a cushion in the event of blood loss. If combined with cardiovascular exercise, it can massively improve her cardiovascular fitness (an effect similar to blood doping). Again, I will discuss this more at length in a future post.


0.5 -2 kg