In the UK there are currently no clear guidelines around weight gain during pregnancy although this advice is needed urgently as weight gain before pregnancy and too much during pregnancy can lead to health risks for mother and baby.
Gaining weight gradually during your pregnancy is important and although the amount of weight gain will vary amongst individuals, it is likely to be minimal during the first trimester and then increase gradually over the next two. Therefore you will gain most of your weight in the third trimester. Overall weight gain is likely to be around 10-12.5kg however, it is important to recognise that this varies between individuals and to continue to go for check ups with your doctor/health visitor to ensure you and baby are growing well.
Importantly, it is not recommended to try and diet or lose weight DURING pregnancy, although eating a healthy, well balanced diet can help keep you and baby well and can also help you to return to your pre pregnancy weight sooner.