I think February tends to be quite a busy month for a lot of people, at least the folks I know anyway.
What about texting them to set up a firm play date in March? It'll be something for the girls to look forward to.
Can you perhaps set the girls up on Skype? They could have a chat a couple of times a week to maintain their bond.
Pregnant for the first-time?
Not sure where to start? We can help!