Antepartum Testing Health Article

Definition

Antepartum testing involves the use of electronic fetal monitoring (EFM) or ultrasound (US) to assess fetal well-being as determined by the fetal heart rate (FHR) and other characteristics during the antepartal period, which is the period spanning from conception to labor. Antepartum tests include the nonstress test (NST), modified biophysical profile (MBPP), contraction stress test (CST), oxytocin contraction stress test (OCT), biophysical profile (BPP), doppler flow studies, amniocentesis, cordocentesis, and fetal echocardiography.

Purpose

Antepartum testing can start as early as 24 weeks but usually begins after 32 weeks of pregnancy depending on the mother's physical status. It provides a means for the physician and pregnant woman to identify any problems and be alert to any changes that may necessitate additional testing or interventions. The testing results reflect how well the placenta is functioning in its ability to adequately supply blood and, therefore, oxygen to the fetus.

The testing is done for pregnancies at risk for maternal and/or fetal complications. Some of these risks include:

• any chronic illness in the mother, such as high blood pressure, diabetes, or autoimmune diseases, including systemic lupus erythematosus (SLE)
• problems with previous pregnancies, such as a history of unexplained stillbirth
• fetal complications, such as intrauterine growth restriction (IUGR) (growth in the fetus below the tenth percentile), birth defects, twins, or other multiple gestations in which a growth discrepancy occurs, such as twin-to-twin transfusion syndrome
• problems in current pregnancy, including pregnancy-induced hypertension frequently referred to as preeclampsia); gestational diabetes (diabetes caused by pregnancy) requiring the use of insulin; premature rupture of the membranes (PROM); too little or too much amniotic fluid (the liquid surrounding the fetus) called oligohydramnios and polyhydramnios, respectively; vaginal bleeding; placental abnormalities, i.e., partial abruption (a portion of the placenta pulls away from the wall of the uterus), or placenta previa (a condition in which the placenta is covering the cervix instead of near the top of the uterus)

Antepartum testing is also used in low-risk pregnancies to evaluate decreased fetal activity, a lag in fundal height (as measured from top of the pubic area to the highest point in the midline at the top of the uterus), and postdates or post-term pregnancy. A normal pregnancy is 40 weeks and testing should begin at 41 weeks to assess the status of the placenta, which may no longer be capable of meeting the baby's needs. This can be indicated by the FHR pattern, amniotic fluid status, and fetal movement patterns.