You get up often to the baby at night? You sleep only few hours at once? Or at all? You have to jump to your baby from your deepest sleep? These are factors result in rigid muscles, bad movement coordination, and not too good nerve-muscle connections.
What does that mean? These are situation where you can easily injure yourself. Based on aptitude, it can lead to lumbago or spinal hernia.
Most of the baby beds have bars and are lying low, which means that you have have to lift weight from deep and you also put it back there. That does not differ too much from a deadlift exercise in the gym except here the weight cries when lifted.
In the gym, the deadlift exercise is an advanced technique and it needs an accurate setup. On the contrary, a beginner mother starts this without any warm-up. The rule is the same in both cases: before lifting, stretch your waist so your body gets straight and bend your knees. So the lifting should happen with straight torso, from the limbs and bottom.