36 weeks

From Babycenter:
Your baby is still packing on the pounds — at the rate of about an ounce a day. He now weighs almost 6 pounds (like a crenshaw melon) and is more than 18 1/2 inches long. He's shedding most of the downy covering of hair that covered his body as well as the vernix caseosa, the waxy substance that covered and protected his skin during his nine-month amniotic bath. Your baby swallows both of these substances, along with other secretions, resulting in a blackish mixture, called meconium, will form the contents of his first bowel movement.

At the end of this week, your baby will be considered full-term. (Full-term is 37 to 42 weeks; babies born before 37 weeks are pre-term and those born after 42 are post-term.) Most likely he's in a head-down position. But if he isn't, your practitioner may suggest scheduling an "external cephalic version," which is a fancy way of saying she'll try to coax your baby into a head-down position by manipulating him from the outside of your belly.