Invasive diagnostic procedures like amniocentesis and chorionic villus sampling (CVS) are performed under ultrasound guidance to obtain amniotic fluid and chorionic villi (or placental tissue) respectively to check for certain conditions during the pregnancy. These procedures are safe when performed by experienced operators though they are associated with procedure-related risks of miscarriage ranging from 0.1-0.3%. Antibiotics used during the procedure have not been shown t

QF-PCR is a common test used in many laboratories for the quick identification of the common chromosomal aneuploidies like Trisomies 21/18/13 and sex chromosomal aneuploidies such as 45XO, 47 XXX, 47XXY and 47XYY. It checks on the number of specific chromosomes like 21, 18, 13, X and Y. QF-PCR technique allows the results to be released within 2-3 working days. It is a test performed on amniotic fluid and chorionic villi obtained via amniocentesis and chorionic villus samp

Conventional karyotype is a genetic test that examines the size, shape and number of chromosomes in a sample of cells. The turn around time for this test is about 2 weeks, and may take longer if the cell culture is slow. Common chromosomal disorders such as Down syndrome (Trisomy 21), Edward syndrome (Trisomy 18), Patau syndrome (Trisomy 13), Turner syndrome (45XO) and other sex chromosomal abnormalities (e.g. 47XXX, 47XXY, 47XYY) can be diagnosed by a conventional karyotyp

Chromosomal microarray (CMA) test allows the detection of clinically significant microdeletions or microduplications that are bigger than 50,000 to 100,000 DNA bases, a resolution that is 50-100 x higher than that of conventional karyotype. It detects most gross chromosomal abnormalities detected by standard karyotype. Since 2010, the American College of Medical Genetics has recommended CMA test (instead of karyotype) as the first tier testing in individuals with with develo

Introduction DNA sequencing is the process of finding the order of the building blocks (i.e. nucleotides) of the genetic code of an individual. Whole exome sequencing (WES) is a widely used next-generation sequencing (NGS) method that involves sequencing the protein-coding regions (exome) of the genome. The human exome represents 1-2% of the genome, and mutations within the exome are known to cause about 85% of the diseases caused by genes. Therefore WES is thought to be a

Introduction DNA sequencing is the process of finding the order of the building blocks (i.e. nucleotides) of the genetic code of an individual. Whole genome sequencing (WGS) is a next-generation sequencing (NGS) method that is increasingly being used, and it involves sequencing both the non-protein coding (introns) and protein coding (exon) regions in an individual. It is currently the most comprehensive genetic test available and would obviate the need to do WES and CMA.

Single gene testing may be performed on amniocentesis or CVS sample if a specific gene abnormality is suspected because of: 1. very unique features on ultrasound scan 2. previous history of such a specific gene abnormality in a previous baby where parents were found not to have carry similar genes (usually such cases are counselled that there is a 1-2% risk of recurrence) 3. family history of a genetic disease where: a) both parents are known to be carriers of a known autoso

Targeted gene panels may be performed on amniocentesis or CVS sample if a specific abnormalities are suspected because of specific fetal abnormalities detected on ultrasound scan (e.g. increased nuchal translucency, heart abnormalities, brain abnormalities). The main advantages of doing targeted gene panels are that: 1. only specific genes in the panel are tested for, and hence avoids the difficulty sometimes of interpreting variants of unknown significance when using more e

Most parents do tests to reassure themselves that the fetus is at low risk for some (not ALL) common chromosomal abnormalities that can...

The thyroid gland at the neck produces thyroid hormones which regulate the metabolism in the body. Common disorders of the thyroid gland...

Hysterectomy is the surgical removal of the womb. Often, this is considered as a last ditch attempt after failed medical treatment to...

Iron deficiency is common during pregnancy. This is especially common amongst pregnant women in the third trimester. Local studies have...

Research shows that having a BMI of 25 or higher (which is considered overweight) can increase certain risks during pregnancy, delivery,...

BMI is weight in kilograms divided by the square of the height in metres. There is now much data that shows that the following risks are...

Recommendations for breastfeeding 1. Exclusive breastfeeding is recommended for up to 6 months, and continued breastfeeding beyond that...

Benefits to breastfeeding For the infant 1. Human breast milk is specific for the needs of human infants. 2. Breastfed infant takes what...

Aims of a pre-pregnancy check-up 1. Investigate for potential problems that may reduce fertility 2. Optimise control of pre-existing...

Adapted from the Perinatal Society of Singapore's Guidelines published in 2020 1. Physical activity and exercise are beneficial during...

Both the mother (up to 10%) and the father (up to 5%) can experience mental health issues during the pregnancy and after birth. It is...

What is iron deficiency in pregnancy? During pregnancy, your body produces more red blood cells to support the growth of the fetus. Iron,...