How can I get my toddler to sleep thru the night?

My daughter will be two soon and we are expecting our second child in February. Recently, she is not able to sleep unless I am with her, so both of us are not sleeping thru the night. I've left her in her crib to cry until even my husband can't stand it and I have a nightly routine with her to help her fall asleep. But she still wakes up and will not sleep unless I lay down with her or put her on the couch with myself and my husband (if he's awake). Help I need advice/suggestions. Is this a phase or something I should be concerned about?