My doctor gave me a list of medications that are safe to take during pregnancy and milk of magnesia was included on the list.
Go for a walk it'll help get things moving and you can take milk of magnesia to help but do NOT self medicate for more than 24 hours.
Water, fruit and vegetables, I ate an activia yogurt every day, and exercise.
My gf told me "fruit cups" she just keeps tell me after a couple of fruit cups she was much better.
Drink lots of water and eat fiber rich foods (fruits and vegetables work great for me but there's plenty of fiber rich foods). If you still can't go, metamucil, colace, and milk of magnesia are safe to take while pregnant.