Dictionary of surrogacy terms II

 In the world of fertility in general and surrogacy in particular, there are a number of important terms and concepts that it’s recommended to understand. If you are considering a surrogacy process, this article will help you understand some of the technical terms. Additionally, you can view the first post on surrogacy terms here: https://www.tammuz.com/dictionary-of-surrogacy-terms/

Amniocentesis

Amniocentesis is a medical procedure that involves extracting a small amount of amniotic fluid from the sac surrounding the fetus in the uterus. This fluid contains cells and other substances that provide important information about the baby’s health. The procedure is typically performed between the 16th and 22nd weeks of pregnancy, when a thin needle is inserted through the surrogate mother’s abdomen and guided by ultrasound to collect amniotic fluid. The collected material is then analyzed using molecular methods to identify genetic abnormalities such as Down syndrome, other chromosomal abnormalities, and neural tube defects.

In addition to testing for genetic abnormalities, the amniotic fluid sample collected during the procedure can be used for further testing as needed, based on specific issues that arise during the pregnancy. While amniocentesis is generally safe, it is an invasive procedure and carries certain risks such as the possibility of miscarriage, infection, or injury to the fetus or uterus. This test is usually performed when there is a clear medical indication or when parents want more detailed information about the fetus’s health.

Non-Invasive Prenatal Testing (NIPT)

NIPT is a screening test used during pregnancy to assess the risk of certain genetic conditions in the fetus. It analyzes small fragments of fetal DNA that circulate in the pregnant woman’s blood. These DNA fragments, known as cell-free DNA (cfDNA), originate from the placenta and are found in the mother’s bloodstream.

A basic NIPT is typically performed after the 10th week of pregnancy and primarily screens for chromosomal abnormalities including:

• Down syndrome (Trisomy 21): Tests for the presence of an extra chromosome 21.
• Edwards’s syndrome (Trisomy 18): Tests for the presence of an extra chromosome 18.
• Patau syndrome (Trisomy 13): Tests for the presence of an extra chromosome 13.

What is this trisomy and monosomy that appears everywhere?

Each person has 23 pairs of chromosomes – a total of 46 chromosomes, with half coming from the biological mother and half from the biological father. This is a normal, healthy situation. When do we have a problem? There are three problematic situations that these tests detect:

• Monosomy- instead of a pair of chromosomes we have only one. That is, only one chromosome was received from one of the biological parents.

• Trisomy – as its name is, “tri” (3): instead of one chromosome, two chromosomes were transferred from one of the parents and now instead of a pair we have triplets.

• The last problematic situation is when the chromosome passed down from the parent has a deficiency, that is, it is not “whole”.

As mentioned, the basic test includes 3 common syndromes and there are more extended tests that examine 7 syndromes and those that examine even 100 syndromes or more.

NIPT can also detect other chromosomal conditions, such as sex chromosome abnormalities (Turner syndrome, Klinefelter syndrome) and certain microdeletions and can predict the sex of the baby. This is a non-invasive procedure that only requires a blood sample from the pregnant woman, without risk to the fetus. It has a high accuracy rate for detecting certain genetic conditions but is not considered a diagnostic test. This means that if there is a high-risk result from NIPT it can indicate a higher likelihood of a genetic condition, but is not absolute.

Additional diagnostic tests, such as amniocentesis or chorionic varicocele sampling (CVS), are usually recommended to confirm the results if the NIPT test indicates a possible problem.

Triple Test (also known as Maternal Serum Alpha-Fetoprotein Test)

The triple test is a prenatal screening test performed during the second trimester of pregnancy. This test measures the levels of three specific substances in the pregnant woman’s blood to assess the risk of birth defects or genetic abnormalities in the fetus.

The three substances measured in the triple test are:

• Alpha-fetoprotein (AFP): AFP is a protein produced by the fetal liver. AFP levels in a pregnant woman’s blood can help assess the risk of neural tube defects (such as spina bifida) and abdominal wall defects. High or low levels of AFP may also be associated with other conditions.
• Human chorionic gonadotropin (hCG): hCG is a hormone produced by the placenta during pregnancy. High levels of hCG may indicate an increased risk of chromosomal abnormalities such as Down syndrome (trisomy 21).
• Unconjugated estriol (uE3): Estriol is an estrogen produced by the fetus and placenta. Low levels of estriol may be associated with certain genetic disorders including Down syndrome and trisomy 18.

The triple test is usually performed between the 16th and 19th weeks of pregnancy. The test results, along with the mother’s age and other factors, provide a risk assessment for specific conditions such as Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), Patau syndrome (trisomy 13), and various problems with the fetal neural tube, brain, and spine.

Currently, there is also a quad screen available, which includes the three components of the triple test and additionally measures Inhibin A. Elevated levels of Inhibin A are an indicator of an increased risk of Down syndrome.

Glucose Tolerance Test (GTT)

Commonly known as a “sugar load test,” a glucose tolerance test is a medical examination that assesses how well the body processes glucose, the primary sugar found in the blood. This test is typically used to diagnose diabetes, prediabetes, and gestational diabetes (a type of diabetes that can develop during pregnancy). It’s usually performed between weeks 24-28 of pregnancy, unless there’s a medical reason to do it earlier or later. There are different types of GTTs, depending on the specific situation of the individual, and they are designed for:

• Oral Glucose Tolerance Test (OGTT): This test is specifically used to diagnose gestational diabetes in pregnant women and involves the following steps:
  1. 50-gram glucose load: A screening test where a blood sample is taken from the pregnant woman after fasting. Immediately afterward, she drinks a glucose solution (usually 50 grams of glucose, hence the name of the test) and blood sugar is measured after one hour to assess insulin resistance. If the results are above a certain threshold (usually above 130/140 milligrams per deciliter), a follow-up test is recommended.
  2. 100-gram glucose load: In cases where the standard glucose load yields readings above 140 milligrams per deciliter (approximately 15% of women), or if the treating physician recommends it, the pregnant woman will undergo a 100-gram glucose load. This test is similar to the 50-gram glucose load, with the main differences being the amount of powder the pregnant woman drinks (100 grams, hence the name) and the fact that four blood tests are taken over a 3-hour period.

If the results are above 95 mg/dL in the first test after fasting, 180 mg/dL after 1
hour, 155 mg/dL after 2 hours, and 140 mg/dL after 3 hours, respectively, then the doctor will recommend appropriate treatment for gestational diabetes.

•  Intravenous Glucose Tolerance Test (IVGTT): In this test, glucose is administered intravenously, and blood samples are taken at various intervals to assess how quickly glucose is cleared from the bloodstream. This test is less common in pregnancies and is usually performed in cases of specific risks.
  
  
• Interpretation of GTT results

1. Normal: Blood sugar levels rise after consuming the glucose solution and then fall as insulin helps the glucose enter the cells.

2. Impaired glucose tolerance (pre-diabetes): blood sugar levels are higher than normal but not high enough to be classified as diabetes.

3. Diabetes: blood sugar levels remain high above a certain threshold.

For gestational diabetes, the criteria for diagnosis may vary slightly, but high blood sugar levels at specific time points indicate a diagnosis. The GTT is an essential tool in the diagnosis and management of diabetes and gestational diabetes, allowing early intervention and management to prevent complications.

Understanding these key terms is essential, so if you are considering getting involved in the surrogacy process in Australia, we wish you the best on your exciting journey towards starting a family.

For any questions, you are welcome to contact the Tammuz team and we will be happy to help.

Tammuz family: We are an international company specializing in international surrogacy, fertility, and egg donation.
For more information: [email protected]

This content was created to provide information only, may change over time and does not constitute a medical opinion or a medical substitute for a consultation with a doctor.
For any medical question, please talk to your doctor regarding your medical condition. Good Luck!