In the 1st trimester you know you are pregnant, but your body’s shape doesn’t really change and baby's movements while constant will be too small to notice.
By your 2nd trimester (from 12 weeks) you will begin to see your ‘bump’ developing and notice your baby move- most women begin to feel their baby move between 16-24 weeks. This can feel like ‘gas’ in your tummy at the beginning! As your baby grows the movements become stronger and more pronounced.
By 24 weeks you should be able to feel and see your baby move. If you are not feeling your baby move by this stage, you can speak to your community midwife about your concerns and they can have a listen to your baby’s heartbeat.
By 28 weeks your baby should have developed a routine, periods when they are awake and when they sleep. You know your baby best and if you are concerned by the movements you should always speak to your maternity unit and discuss with them. They are open 24hrs a day and you are not disturbing them. It is always better to get it checked out rather than worrying at home.
Babies movements DO NOT decrease as they get bigger. They should maintain their routine right up until birth.