Ay, hindi ako doc pero based sa sinabi ng OB ko before, ang FL:BPD ratio na yan (femur length to biparietal diameter) is one of those measurements they check to make sure baby's proportions are normal, 20% difference ay usually within the normal range at 29 weeks, pero dapat talaga i-confirm ng doctor mo kung okay lang yan base sa full ultrasound results mo. Marami sa amin may slight variations sa measurements tapos nag-turn out fine naman, pero since pregnancy monitoring varies, best to ask your OB directly kung may concern sila or kung kailangan mo pa ng follow-up ultrasound, they'll know your full picture better. Don't stress yourself too much muna, pero do bring it up sa next appointment mo para peace of mind!