Week 39 Update
How your baby's growing: Your baby's ready to greet the world! He continues to build a layer of fat to help control his body temperature after birth, but it's likely he already measures about 20 inches and weighs a bit over 7 pounds. (Boys tend to be slightly heavier than girls.) Your baby's organs are fully developed and in place, and the outer layers of skin are sloughing off as new skin forms underneath.
How your life's changing:
At each visit, your midwife or doctor will do an abdominal exam to check your baby's growth and position. She might also do an internal exam to see whether you've started effacing (when the cervix thins out) or dilating (when the cervix opens). If the week passes and your baby stays put, don't panic. Only 5 percent of babies are born on their scheduled due date. And your baby can't make you wait indefinitely for his arrival. If you go past your due date, your provider will schedule you for fetal testing (usually a sonogram) after 40 weeks to ensure that it's safe to continue the pregnancy. If you don't go into labor on your own, most practitioners will induce labor when you're between one and two weeks overdue.
Pregnant women on television sitcoms always have their water break dramatically — in the middle of a crowded room, of course — just before going into labor. Don't worry about a similar scenario happening to you. Membranes rupture before the beginning of labor in less than 15 percent of pregnancies, and it's not normally an enormous gush — usually a small gush or a slow leak. In any case, if your water does break (or you even suspect you might have a leak), call your doctor or midwife right away, but stay calm — it may be hours before your first contraction. (If you're a GBS carrier, you'll be asked to go to the hospital so you can start getting IV antibiotics and will likely be induced at the same time if you don't start contracting on your own.) Also call your practitioner right away if you notice that your baby's movements have slowed, whether or not you're leaking fluid.
There are more common signs of impending labor than water breaking. You may notice your mucus plug — the small amount of thick mucus that blocks your cervical canal — in your undies or in the toilet. It might be tinged with a small bit of brownish, pink, or red blood (which is why it's called "bloody show"). (If you have vaginal spotting or bleeding other than mucus tinged with a tiny amount of blood, call your caregiver without delay.) Labor usually starts within a day or two of seeing the mucus plug. Another sign of labor is contractions at regular — but increasingly shorter — intervals. If you've been having Braxton Hicks contractions, you'll now realize that these were just practice. Your doctor or midwife will tell you when to give her a call, but it will likely be once your contractions last about a minute each and arrive every five minutes for about an hour. (Time the contractions from the beginning of one to the beginning of the next one.) If you're unsure about your progress, go ahead and give your practitioner a call.
Your practitioner may have you count fetal movements. Even if you aren't asked to formally count movements, call her immediately if you notice a decrease in your baby's activity. Your baby should remain as active as ever right up to delivery, and a decrease in activity could be a sign of a problem — meaning that you need to deliver now rather than later.