From What to Expect:
Only two more weeks (or plus two more, max) before your baby makes his or her appearance. And what an adorable appearance that will be! Your little one isn't so little anymore — weighing in at close to seven pounds and hitting the height charts at the 21-inch mark (or less).
As you prepare (best you can) for baby's ETA, he or she is also getting ready, big time. Vernix and lanugo continue to shed from your baby's body into the amniotic fluid. Your baby swallows that amniotic fluid (yum yum?) and some of it winds up in his or her intestines where it — along with other shed cells, bile, and other waste products (triple yum) — will turn into your baby's first bowel movement (meconium) and perhaps your first diaper change.
Your baby's lungs continue to mature as more and more surfactant is secreted (remember — it helps prevent the lungs from sticking to each other when your baby begins to breathe…definitely a good thing).