Aw mama, I understand your worry kasi ganyan din ang naging concern ng one of my mum friends during her second trimester, ang baby's femur ay delayed compared sa gestational age niya. Ang best thing talaga is to follow up with your OB para ma-monitor closely, kasi may maraming reasons why this happens (sometimes it's just genetics or measurement timing, sometimes baby just catches up later) at sila lang ang makakapag-do ng proper assessment at repeat ultrasound. Marami sa aming group na nakaexperience nito and most turned out fine, pero iyong peace of mind ngayon is really important so don't hesitate to ask your doctor kung kailangan ng specialist referral or more frequent monitoring, that's what they're there for, girl. Sending you strength through this wait!