The Third Trimester
The Normal Pregnancy:
In normal pregnancy, the third trimester is a little longer because there's a variation in lengths of pregnancies, with "term" considered anywhere from 37 to 42 weeks. A due date is just the middle of the bell curve, and your baby will have his or her own clock, so think of if as your due month.
As you near your due date, a physician or nurse will check your cervix for change—a predictor for how imminent labor is. Some practitioners check as soon as 37 weeks, some not until after the due date.
This is the time for philosophical discussions regarding elective induction, because if there are no medical indications for induction, elective induction should be done only at or after 39 weeks–and you should expect it to be your call. Even though two weeks past the due date is considered the time to act no matter what, extra surveillance should begin right after the due date because your baby keeps growing but the placenta may start dying, and your baby's needs may outpace the placenta's ability to deliver.
Non-stress tests and additional ultrasound may be prudent at this time. The third trimester is the time most likely to see pregnancy-related complications of pregnancy-induced hypertension, so signs of this are of the utmost importance. Gestational diabetes is screened for at or around 26 weeks. Group B strep cultures are obtained at around 28 weeks.
The High-Risk Pregnancy:
Problems that can make you high risk in the third trimester include:
- The high-risk factors from the first and second trimesters
- Decreased fetal movement
- Abnormal amount of amniotic fluid
- Emotional abnormalities (pregnancy is a stress that may bring out borderline psychiatric conditions)
- Nausea and/or vomiting—not the typical morning sickness of the first trimester. This late in pregnancy, liver problems may be the cause, from a sneaky PIH variant called HELLP which would prompt immediate delivery to a more benign gallbladder problem which can be addressed after delivery.
- Right upper quadrant pain.
- Decreased "reactivity" on non-stress test, in which the baby's heart rate does not accelerate after movement, which is the expected norm.
Pregnancy is a condition in which one can be normal one moment and be blindsided by a problem the next. For this reason, every doctor has a routine for keeping an eye out for warning signals in every pregnancy. High-risk patients have a series of appointments tailored just for them. In your visits to your obstetrician, you should expect all of the screenings that this year has to offer—not last year's obstetrics. You should expect your doctor to follow your pregnancy appropriately, whether you're high risk or not. And you should expect him or her to know the difference.