hi, yes its the fluid, one bub is taking too much and the other doesnt have enough. any info would be great thanks! she said the babies are identical also. we didnt find out the sex she stopped the scan once she realised there was a problem. The scan showed one bub was 4-5 days behind the other growth wise so it had only happened recently but she wasnt sure how rapidly the fluid was going. i hope that all makes sense!