Hi momshie! Variable lie basically means ang baby mo ay hindi pa naka-settle sa isang position, sometimes head down, sometimes sideways, sometimes butt down, kaya "variable" talaga. Totally normal pa sa 18 weeks kaya don't worry, marami pang oras ang baby mo mag-position properly bago ka mag-deliver! A few of us moms had the same thing and lahat nag-settle na by 34-36 weeks, pero para sa peace of mind mo, best to ask your OB directly kung may concern siya or kung kailangan mo ng check-ups pa along the way.