I just had a baby and I hid the pregnancy from my step son until the third trimester. It was worth the secrecy. This is my first child and my husband's second. As a high risk pregnant woman, the last thing I needed was additional stress in my life. Navigating a complicated pregnancy as a stepmom is not for the weak. Pregnancy is a time filled with anticipation, joy, and sometimes anxiety. For a step mom expecting a child in a blended family, especially when co-parenting invo