It is understandable, with the natural weight gain of pregnancy, and your changing body shape that you should find your posture is affected in pregnancy.
Just as when you are coming home from shopping with a heavy bag which makes you tilt to one side, the changes of pregnancy make you alter how you comfortably walk, sit and even sleep as your bump grows.
Possible problems with posture in pregnancy
The extra weight and the way in which you might be shifting your centre of gravity can cause problems like
sciatica (pain which runs down into your leg), back pain and consequently, even headaches.
In preparation for the birth, your body is going through hormonal changes in order to allow the muscles to relax and let your frame grow comfortably. This can mean that changes in your posture are more quickly felt through back pain etc because your muscles aren't supporting you as they usually do.
Retaining good posture in pregnancy
Your growing bump is most likely to affect your posture by encouraging you to arch your back more, pushing your tummy forward. Be aware of this and realign your body, making sure your neck and back are straight with each other.
Every now and again, sit up straight and gently push down on your shoulders, WITHOUT OVERSTRETCHING. Just the smallest movement should feel free; if it feels tight or bruised, you are taking too much pressure on the top half of your body and you need to do small stretching exercises and relax more often.
When you are relaxing, make sure you are sitting properly on a chair or sofa where your back and neck are well supported, and don't stay sitting down for too long at a time. Even if you are resting, getting up to make a cup of tea or a quick potter around every now and then is good for your legs, back and circulation.
Pregnancy is often a time when women find they don't get a good night's sleep. This extra tiredness can make posture worse during the day. Additionally, twisting around to get comfortable in bed can affect your body alignment. Make sure your pregnancy sleeping positions are correct, and you will soon notice a real difference through the day and the night.