Femur length running behind .

I'm having monthly growth scans because of previous Small for gestational age baby .. he was exact to date in all other measurements except femur length which was less than 8 percentile from 20 weeks onwards . when he was born, he was 5lbs 8oz and 181/4 inches in length. Now with this pregnancy, baby was measuring right on track as per my anatomy scan but at 24 weeks scan ,femur length was one week behind and I'm afraid that it will be like this on all of remaining scans .Does anyone else have same problem? Is there anything I can do dietwise to boost overall baby weight and femur length. I know it depends on genetic background. my husband is 5'8 & I am 5'3 .