The Third Trimester of Pregnancy: An Overview

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With delivery imminent, women have questions during the third and final trimester of pregnancy. Learn what to expect in your last weeks of gestation from your baby, your body, and your healthcare provider.

The third trimester of your pregnancy, from 27 weeks until 40 weeks or delivery, centers mostly on your baby. You and your doctor are now awaiting your growing babe to attain maturity and finally begin the delivery process. Throughout the third trimester, there is a heightened vigilance for any diseases and complications unique to pregnancy.

With your delivery just around the corner, you may be feeling nervous and have some concerns. Here's a look at some common questions many women ponder during this late stage of pregnancy.

Monitoring the Fetus: The Biophysical Profile

Modern technology allows for extensive monitoring of the fetus. Doctors can see your unborn baby through ultrasound, take exact measurements to determine growth, and often confirm the baby's position by physical exam. Doctors can measure amniotic fluid, a normal amount being one of the most crucial determinants of fetal well-being. Doctors can also directly observe fetal movement, tone, and even breathing-like movements, statistically assuring a mother-to-be of her baby's good health.

Another test, the non-stress test (NST)–also called fetal activity determination (FAD)—makes use of the valuable relationship between fetal movement and fetal heart rate. When you run around the block, your own heart begins to race. This is your body's way of speeding up the process of delivering more oxygenated blood to the muscles, where it is needed most. In the same way, when a baby moves, which the mother marks on a fetal monitor, we should also see a corresponding rise in fetal heart rate. This tells us that everything is pretty much working right in the baby, too.

The combined results of the ultrasound exam and the NST are referred to as a biophysical profile. Scores are assigned by adding all of the criteria which are met. Over the years, many researchers have exhaustively tabulated what these results mean. When all of the normal ultrasound items are found, and the non-stress test is normal, their statistics have demonstrated that a baby has a 99 percent or better chance of another week's worth of fetal well-being ahead. So doing these evaluations once or twice a week on high-risk mothers is essential.