1st trimester
1-5 weeks
The size of a grain of rice, in the first month your baby is busy developing a spinal cord, nervous system, gastrointestinal system and also heart and lungs.
6-9 weeks
Less than an inch long, baby’s face is forming, arms and legs are moving and their brain is developing further.
10-13 weeks
Three inches long, weighing about 1oz, with wiggling finger and toes. He’ll even have tiny fingerprints now.
2nd trimester
14-17 weeks
Baby is about five inches long, weighs around 5oz and now has tiny finger and toenails!
18-22 weeks
Nearing 12inches in length, with hair, eyelashes, eyebrow and even hiccup! Baby can now hear your voice and you’ll start feeling movements.
23-27 weeks
Eleven to fifteen inches long and weighing over 1lb, baby’s eye can open. Baby will start to store fat and look more like a baby!
3rd trimester
28-32 weeks
Now 14 to 17 inches long, weighing 3lb, your baby is putting on body fat and his lungs are also developing.
33-36 weeks
16-18 inches, 4-5lb, baby wakes and sleeps in cycles and should respond to sounds, especially your voice.
37-40 weeks
About 19 inches long and approx 6lb your baby is fully formed and ready to come into the big world! 
