ANTEPARTUM | PREGNANCY TESTS | Maternity

What NCLEX Cares About

The purpose, basic procedure, and correct interpretation of each test.
What to do when results are not reassuring.
When a test is contraindicated or must be repeated.

Clinical Decision Guide

Routine surveillance

Start with an NST (or a modified BPP).

Nonreactive NST

Extend the test and use vibroacoustic stimulation. If still nonreactive, perform a BPP (preferred) or CST.

Abnormal results

A positive CST, a BPP of 4 or less, or oligohydramnios → stabilize the client, consider gestational age, and prepare for possible birth.

MEMORY TOOL

NST: “Reactive is reassuring” (you want accelerations). CST: “Negative is nice” (you do not want late decelerations).

Nonstress Test (NST)

Purpose: assesses fetal oxygenation and nervous system function through FHR accelerations, which usually occur with fetal movement.

Position

Semi-Fowler’s or side-lying to prevent supine hypotension.

Monitor

Apply the external FHR transducer and a tocotransducer; the client may mark fetal movements.

Duration

Usually 20 minutes, extended to 40 minutes if needed for a fetal sleep cycle.

Result	Criteria	Meaning
Reactive (normal)	At 32 weeks or more: at least 2 accelerations of 15 beats/min or more, lasting 15 seconds or more, within 20 minutes. Before 32 weeks: 10 beats/min for 10 seconds.	Intact fetal nervous system and good oxygenation
Nonreactive (abnormal)	Fewer than 2 qualifying accelerations in 40 minutes	Possible hypoxia — or a sleep cycle, medications, or prematurity. Needs further testing (BPP or CST).

IF NONREACTIVE: Extend the test and use vibroacoustic stimulation per protocol. If the result remains nonreactive, a BPP or CST is performed.

THINK SIMPLE

The NST looks for a baby whose heart rate speeds up with movement. Two good accelerations in 20 minutes = reactive = reassuring.

Contraction Stress Test (CST)

Purpose: evaluates how the FHR responds to the stress of uterine contractions; screens for uteroplacental insufficiency. The CST is used less often today because the BPP is easier and safer.

Induce contractions

Nipple stimulation or low-dose IV oxytocin.

Goal

At least 3 contractions lasting 40 seconds or more within 10 minutes.

Observe

Watch for late decelerations; stop the oxytocin and position the client on the side if contractions are too frequent.

Result	Criteria	Meaning
Negative (normal)	No late or significant variable decelerations	Good placental function; reassuring
Positive (abnormal)	Late decelerations with 50% or more of contractions	Uteroplacental insufficiency; birth is considered based on gestational age
Equivocal (suspicious)	Intermittent late decelerations or significant variable decelerations	Repeat or evaluate with a BPP
Unsatisfactory	Fewer than 3 contractions in 10 minutes or a tracing that cannot be interpreted	Repeat the test

CONTRAINDICATIONS: Placenta previa, previous classical uterine incision or extensive uterine surgery, high risk of preterm labor, preterm rupture of membranes.

THINK SIMPLE

The CST asks: can the baby handle contractions? Negative = no late decelerations = good. Positive = late decelerations with half or more of contractions = not good.

Biophysical Profile (BPP)

Purpose: combines the NST with an ultrasound of four fetal variables. Each of the 5 components scores 0 or 2; the maximum score is 10.

Component	2 Points (Normal)	0 Points (Abnormal)
NST (FHR reactivity)	Reactive	Nonreactive
Fetal breathing movements	At least 1 episode lasting 30 seconds or more in 30 minutes	Absent or shorter than 30 seconds
Gross body movements	3 or more body or limb movements in 30 minutes	2 or fewer movements
Fetal tone	At least 1 episode of extension with return to flexion (or opening and closing a hand)	Slow, partial, or absent extension and flexion
Amniotic fluid volume	At least one pocket of fluid more than 2 cm deep	No pocket of at least 2 cm (oligohydramnios)

Score Interpretation

Score	Interpretation
8–10 (with normal fluid)	Normal; reassuring
6	Equivocal; repeat testing or consider birth depending on gestational age
4 or less	Abnormal; possible fetal hypoxia — prepare for possible birth

MOST IMPORTANT PREDICTOR — AMNIOTIC FLUID VOLUME: NST, breathing, movement, and tone reflect acute oxygenation. Amniotic fluid reflects chronic placental function: low fluid (oligohydramnios) suggests long-term placental insufficiency and needs evaluation even when the total score looks acceptable.

Other Antepartum Fetal Assessments

Assessment	Key Points
Fetal movement counts (“kick counts”)	Count daily from about 28 weeks; lying on the side, often after a meal. Fewer than 10 movements in 2 hours, or a clear decrease, requires evaluation (usually an NST).
Modified BPP	NST plus amniotic fluid assessment; a common routine surveillance test
Umbilical artery Doppler	Assesses blood flow in growth-restricted fetuses; absent or reversed flow is concerning
Amniocentesis	Genetic testing (15–20 weeks) or lung maturity. Before 20 weeks the bladder may need to be full; after 20 weeks, empty. Rho(D) immune globulin for Rh-negative clients. Report fever, bleeding, fluid leakage, cramping, or decreased fetal movement.
Chorionic villus sampling (CVS)	Genetic testing at 10–13 weeks; earlier than amniocentesis; small risk of pregnancy loss; Rho(D) immune globulin for Rh-negative clients

NCLEX Self-Check — Antepartum Fetal Assessment

Select the best answer for each question. Press Submit Answer to view your result and the rationale for every option.

Question 1 of 10

How NCLEX Tests Fetal Assessment

NCLEX questions ask you to interpret results, choose the next step after a nonreactive NST, identify contraindications to the CST, score the BPP, and teach fetal movement counts.

Clinical Judgment Connections

Clinical Judgment	Application
Recognize Cues	Identify accelerations, decelerations, fetal movement, and amniotic fluid findings.
Analyze Cues	Classify results as reassuring, equivocal, or abnormal.
Prioritize Hypotheses	Positive CST, BPP of 4 or less, and oligohydramnios come first.
Generate Solutions	Plan the next test, repeat testing, or preparation for birth.
Take Action	Position the client on the side, stimulate the fetus, stop oxytocin for tachysystole, and notify the provider.
Evaluate Outcomes	Reassess the FHR tracing and repeat testing as ordered.

NCLEX KEY POINT

Start with the NST → if nonreactive, extend and stimulate → then BPP. A positive CST or a BPP of 4 or less suggests the need for birth. Low amniotic fluid is a red flag on its own.