Your baby is just about as big as he's ever going to get in week 40. He's more than 21 inches long from head to toe and weighs about 7 and a half pounds.
Although he's still attached to you, he's his own person. He has his own memories, and he can recognize familiar sounds and tastes. He knows what he likes (chewing on his hand, kicking) and what he doesn't like (cramped living quarters). He already has more than 70 different reflexes that will help him survive in the outside world. For one thing, he knows what to do with a nipple. He also knows how to cry for attention. All he needs is a little air in his lungs and a willing audience.
As soon as he's born, his progress will be put to the test -- the Apgar test, to be exact. Within one minute of birth, a doctor, nurse, or midwife will give him a score of 0 to 2 in five different categories: heart rate, breathing, muscle tone, color, and reflexes. The exam is then repeated again in five minutes.
Don't be alarmed if your baby doesn't score a perfect 10 -- very few babies do. An Apgar score of 7 or above is considered normal. Your baby may have a slightly lower score if he was born prematurely or had a difficult delivery. Most children born with low Apgar scores turn out to be perfectly healthy. The Apgar test is repeated at five minutes because it is not uncommon for babies to come out a little stunned and take a couple minutes to perk up. This second score is more predictive of how much care or intervention the baby will need.
The Apgar test, developed by obstetrician Virginia Apgar more than 50 years ago, can't tell whether a child will have any long-term disabilities. (A very low score has been associated with a higher-then-normal risk of cerebral palsy, but 90 percent of the low-scoring babies fail to develop that disorder.) Instead, it helps identify babies who may need immediate medical assistance. It's also a strong predictor of survival, especially for preterm infants.
The true measure of your baby's health will come in the following weeks and months. Watch him grow, track his progress, and take him to the pediatrician for his scheduled checkups. Congratulations, and enjoy!
American Academy of Family Physicians. Pregnancy Calendar.
Campbell, Stuart, MD. Watch Me Grow. St. Martins Griffin.
Curtis, Glade, MD. Your Pregnancy Week by Week, 5th edition. Da Capo Press.
American Pregnancy Association. Your child's first test: The Apgar. http://www.americanpregnancy.org/labornbirth/apgartest.html
Casey, BM et al. The continuing value of the Apgar score for the assessment of newborn infants. New England Journal of Medicine. Vol. 344(7): 467-471.
Fetal memory: Does it exist? What does it do?. ACTA PDIATRICA SUPPLEMENT, Volume 416: pp. 16-20, (Available at: http://www.cirp.org/library/psych/hepper1/)