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 (ther period spanning conception and labor).

Purpose

Antepartum testing can start as early as 24 weeks but usually after 32 weeks of pregnancy depending on the status of the mother. It provides a means for the physician and pregnant woman to identify fetal well-being and be alert to any changes that may necessitate additional testing or interventions. The results of testing reflect the functioning of the placenta and 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:

• gestational (insulin requiring) diabetes
• intrauterine growth restriction
• chronic hypertension or pregnancy induced hypertension
• too little or too much amniotic fluid (oligohydramnios and polyhydramnios, respectively)
• history of unexplained stillbirth
• autoimmune diseases, including systemic lupus erythematosus
• multiple gestation
• placental abnormalities, i.e. partial abruption (a portion of the placenta pulls away from the wall of the uterus) or placenta previa (the placenta is covering the cervix and subsequent bleeding occurs)

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

Precautions

Clinicians should only prescribe these tests if they are ready to intervene when faced with ominous data. A fetus is considered viable at 24 weeks, as that is the minimum gestational age for sufficient lung development. There are no significant risks to the mother or the fetus from the nonstress test (NST) or the biophysical profile (BPP). Ultrasound waves utilized for the BPP are painless and safe because this method employs no harmful radiation. There is no evidence that sound waves cause any harm to the mother or the baby.