Trisomy, (Three bodies), is that the affected baby has 47 chromosomes instead of the typical 46. Humans have 23 pairs of chromosomes. In this chromosomal disorder, baby will have an extra. The most common forms are Down syndrome, Patau syndrome and Edward syndrome.
What are the risks?
At conception, the additional chromosome usually occurs spontaneously. The cause is unknown and prevention is not at all possible. Here are some risk factors:
~ Women over 37 years old. Older women are more likely to have babies with chromosomal disorders.
~ Paternal age. Older men (50+ in age) are more likely to father babies with chromosomal disorders.
~ Amount of children a person has given birth to. Women who have had four or more babies have a higher risk.
What are the signs?
During the pregnancy, signs may be evident:
~ Excessive fluid surrounding the baby. (Polyhydramnios)
~ One umbilical cord artery only.
~ Small baby for its gestational date.
~ Small placenta than expected.
~ Less active baby than expected.
~ Congenial defects present: includes- Cleft palate, heart abnormalities. Ultrasound scan can pick this up.
How is trisomy diagnosed?
~ Ultrasound scans
~ Maternal serum screening. (Blood test done at particular times of pregnancy)
~ Amniocentesis. (Withdrawal of amniotic fluid by needle. Fluid is examined.)
~ Chronic villi sampling. Cells are taken from the chorion, tissue that will become the placenta is taken and examined.
Children that are affected usually have birth defects, experience delayed development and intellectual disabilities. You may have heard of different types referred to as trisomy 13 or trisomy 18.
Miscarriage or pregnancy loss is often an unfortunate outcome of this genetic abnormality.