Antenatal Tests for High-Risk Pregnancies: Extra Precautions and Procedures Explained

High-risk pregnancies require specialised care to ensure the safety of both mother and baby. Antenatal tests for high-risk pregnancies focus on identifying potential complications, monitoring foetal development, and tailoring care to meet specific needs. These tests, conducted alongside routine antenatal care, allow healthcare providers to take proactive measures and provide expectant parents with reassurance.

This article explains the additional antenatal tests and precautions taken during high-risk pregnancies, covering their purpose, timing, and how they contribute to a healthy pregnancy.

What Defines a High-Risk Pregnancy?

A high-risk pregnancy occurs when medical or lifestyle factors increase the likelihood of complications for the mother, baby, or both. These factors include pre-existing medical conditions, advanced maternal age, multiple pregnancies, or a history of pregnancy complications. High-risk pregnancies require more frequent antenatal checkups and specialised testing to address potential challenges.

Common Risk Factors for High-Risk Pregnancies

Maternal Health Conditions: Diabetes, high blood pressure, heart disease, and autoimmune disorders.

Age-Related Risks: Women over 35 or under 18 have an increased risk of complications.

Pregnancy-Specific Conditions: Gestational diabetes, pre-eclampsia, and placenta previa.

Multiple Pregnancies: Carrying twins or higher-order multiples increases risks of preterm labour and growth restrictions.

Healthcare providers identify these factors early during routine antenatal appointments and adjust the care plan to include additional monitoring and tests.

Specialised Antenatal Tests for High-Risk Pregnancies

Chorionic Villus Sampling (CVS)

CVS is a diagnostic test that analyses placental tissue for chromosomal and genetic abnormalities. It is typically offered between weeks 10 and 13 and is recommended when screening tests indicate a high risk of conditions like Down syndrome or if there is a family history of genetic disorders.

Procedure and Purpose

CVS involves collecting a small sample of chorionic villi through the cervix or abdomen. The sample is tested for chromosomal abnormalities and genetic conditions such as cystic fibrosis. While CVS is highly accurate, it carries a small risk of miscarriage (about 1%).

Who Needs CVS?

CVS is often recommended for women with abnormal results from first-trimester screenings, such as the combined test or NIPT, or those with a history of genetic conditions.

Amniocentesis

Amniocentesis is another diagnostic test offered from week 15 onwards. It involves extracting a small amount of amniotic fluid to analyse for chromosomal abnormalities, neural tube defects, and infections. This test is usually recommended when CVS is not performed or if further confirmation is needed after NIPT or combined screening.

Benefits and Considerations

Amniocentesis provides definitive results, making it a valuable tool for high-risk pregnancies. Like CVS, it carries a small risk of miscarriage, so it is only performed when necessary.

Non-Stress Test (NST)

The NST monitors the baby’s heart rate and movements to ensure they are receiving enough oxygen. It is a non-invasive test often conducted in the third trimester for high-risk pregnancies. Women with gestational diabetes, high blood pressure, or reduced foetal movements may require regular NSTs to track the baby’s well-being.

What to Expect

During the NST, the mother reclines while a device measures the baby’s heart rate in response to their movements. A reactive result (normal heart rate changes with movement) indicates a healthy baby, while non-reactive results may prompt further testing.

Doppler Ultrasound

Doppler ultrasound assesses blood flow in the umbilical cord, placenta, and foetal vessels. It is particularly useful for high-risk pregnancies involving growth restrictions, pre-eclampsia, or multiple pregnancies.

Importance in High-Risk Pregnancies

Doppler ultrasound helps detect issues such as placental insufficiency, ensuring that interventions are planned early to protect the baby’s health.

Biophysical Profile (BPP)

The BPP combines an NST with an ultrasound to evaluate the baby’s movements, breathing, muscle tone, and amniotic fluid levels. This comprehensive test is often recommended for high-risk pregnancies nearing full term or when reduced foetal movements are reported.

Components of the BPP

Each parameter is scored, and a total score helps determine whether further monitoring or immediate delivery is necessary.

Glucose Tolerance Test (GTT)

High-risk pregnancies often include earlier or more frequent screening for gestational diabetes. The GTT involves drinking a sugary solution and measuring blood sugar levels over several hours to assess how the body processes glucose.

Who Needs the GTT?

Women with a history of gestational diabetes, a BMI over 30, or a family history of diabetes are more likely to require this test early in pregnancy.

Extra Monitoring for High-Risk Pregnancies

Ultrasound Scans

Routine antenatal scans are enhanced for high-risk pregnancies with additional ultrasounds to monitor growth, amniotic fluid levels, and placental health. Growth scans may be scheduled every few weeks to track the baby’s progress and detect potential issues like growth restrictions or preterm labour.

Cervical Length Measurement

Women at risk of preterm labour, such as those with a history of early delivery or uterine abnormalities, may undergo cervical length measurements. This test uses ultrasound to assess whether the cervix is shortening prematurely, which could indicate a higher risk of preterm birth.

Group B Streptococcus (GBS) Screening

GBS screening, conducted between weeks 35 and 37, identifies whether the mother carries GBS bacteria. Women with high-risk pregnancies may receive earlier screening or preventative antibiotics during labour if GBS is detected.

Preparing for High-Risk Antenatal Tests

Emotional Preparation

High-risk pregnancies can bring additional stress, but attending antenatal education classes or seeking antenatal support from healthcare providers and counsellors can help parents feel more confident.

Practical Tips

Communicate Openly: Share any concerns or symptoms with your healthcare provider during antenatal appointments.

Follow Instructions: Tests like the GTT require fasting or specific preparation, so adhere to guidelines for accurate results.

Stay Informed: Learn about each test’s purpose to reduce anxiety and make informed decisions.

Lifestyle Considerations

A healthy lifestyle complements antenatal testing and supports overall well-being. Maintaining a balanced diet rich in essential nutrients and taking antenatal vitamins like folic acid are crucial. Regular physical activity, such as yoga during pregnancy, improves circulation and reduces stress, while practices like prenatal massage promote relaxation.

The Role of Antenatal Clinics

Antenatal clinics are essential for coordinating care during high-risk pregnancies. They provide tailored care plans, ensure timely testing, and offer emotional support to parents. Regular visits to the antenatal clinic help address any issues promptly and keep parents informed about their baby’s health.

Antenatal tests for high-risk pregnancies are critical for safeguarding the health of both mother and baby. From diagnostic procedures like CVS and amniocentesis to monitoring tools like NSTs and Doppler ultrasounds, these tests provide invaluable insights and guide personalised care plans. Regular antenatal checkups, open communication with healthcare providers, and a supportive lifestyle are essential for navigating a high-risk pregnancy. With the right precautions, testing, and support, parents can approach their journey with confidence and optimism.