Popsugar Parenting Pregnancy How Big Is My Baby? A Week-by-Week Fetus-Size Guide Based on Objects You Actually Know 8 June 2018 by Annie Gabillet View On One Page Photo 16 of 36 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 16 Week 20: a Tall Water Bottle Stay hydrated, and remember that this week, your baby is as long as a tall water bottle at 10.08 inches. Previous Next Start Slideshow Pregnancy