At week 25 the baby is now over 1 ½ pounds and about 9 inches in length. The baby continues to accumulate fat and fill out. This is one of the best times to get pictures on a 3D ultrasound. The baby is big enough to look like a little person, facial features are viewable, and the baby is not so big as to get in its own way. 3D ultrasounds can be a lot of fun and the pictures can be phenomenal. They are perfectly safe. These are not medical ultrasounds; they are just photo shoots for the baby.
If the baby is born at 25 weeks it has about a 75% chance of survival. This is getting better but there is still a lot of risk at 25 weeks. The baby is just starting to make surfactant at week 25. This is a chemical produced in the lungs that helps keep the lungs open and functioning. 25 week babies do not have enough surfactant to allow the baby to breath on its own, but this is when surfactant first starts getting produced.
Sleep wake cycle may be apparent at week 25. As the movement continues to become more pronounced, patterns become recognizable. Babies do sleep inside the uterus so it is alright if there are times of the day when there is less movement. Most people are feeling the baby move some throughout the day at week 25 but there will be periods when the baby is more active then other times. Many women feel the baby most when they are lying down in a quit area. This may because there are fewer distractions. This could also be because the baby is not experiencing the gentle rocking motions that take place when you are walking and active.