While it seems like the "home stretch" of pregnancy would be a good time to rest up for the big day and relax, the last trimester can be a time of many potential complications. While most pregnancies progress towards delivery without a hitch, serious problems can arise in the last three months of pregnancy.
Preterm Labor
One out of 10 babies in the United States is born prematurely, before 37 weeks gestation. The fetus is viable around 24 weeks, when the lungs start to produce surfactant, Case Western Reserve Professor Judi Maloni, PhD, RN states. Surfactant is produced in the lungs and helps the lungs inflate so oxygen can be absorbed.
If labor occurs prematurely, drugs called tocolytics may be given to stop labor. Steroid medications to help mature fetal lungs may also be given. Patients may also need to be on bed rest to prevent contractions. Very premature infants have many complications and the survival rate without significant long term problems is low; the longer the fetus stay in the womb, the better chance he has of surviving.
Pregnancy Induced Hypertension
Pregnancy induced hypertension, or PIH, sometimes still called pre-eclampsia, may occur in women who didn't have high blood pressure before they got pregnant, or may complicate chronic hypertension. Around seven in 100 women have PIH, the University of Maryland Medical Center states. Pregnancy induced hypertension is caused by abnormalities with the placenta, and can lead to fetal growth retardation, prematurity and dangerous complications such as seizures and liver failure. Serious complication occur when PIH progresses to eclampsia, which affects one in 1,500 women. Women with pregnancy induced hypertension and their babies need close monitoring, possibly bed rest, and possibly early delivery.
Placenta Previa
Placenta previa is the growth of the placenta across the opening to the uterus, the cervix. Placenta previa is common in early pregnancy. Doctors don't get concerned about it until the third trimester, because the placenta normally migrates up the uterine wall by that time. After six months, this is less likely to happen. Placenta previa causes painless bright red bleeding that can become heavy without warning. Bed rest is usually required to prevent hemorrhage and serious complications for mother and baby.
Abnormal Fetal Presentation
Until the middle of the third trimester, the position of the fetus isn't of great concern. Most babies have plenty of room to turn if they're not in a head down position. However, after 32 weeks, it becomes less likely that a fetus is going to change position, the Family Practice notebook states. Around 3 percent of babies decide not to face the world head on, preferring instead to plant their bottom down or to lie sideways in the uterus. Obstetricians may suggest trying a version, which means attempting to change the baby's position through gentle abdominal manipulation. Others decide a cesarean delivery is the best option; this is the only option if the fetus is transverse, or sideways.
Twins are a complicated situation if one is head down and one head up; if the first is head down, a vaginal delivery may be tried, since the second twin may flip or can be rotated after the first is delivered. Some obstetricians prefer to play it safe and plan a cesarean from the start.
