18w0d Chromosome Chart

your baby’s the size of a mango! 

Your baby’s sensory development is exploding! Her brain is designating specialized areas for smell, taste, hearing, vision, and touch. Some research suggests that she may be able to hear your voice now, so don’t be shy about reading aloud, talking to her, or singing a happy tune if the mood strikes you.

Your baby weighs about 8 1/2 ounces and measures 6 inches, head to bottom — about the size of a large mango. Her arms and legs are in the right proportions to each other and the rest of her body now. Her kidneys continue to make urine and the hair on her scalp is sprouting. A waxy protective coating called the vernix caseosa is forming on her skin to prevent it from pickling in the amniotic fluid.

(Source: The Bump and Baby Center)

Following the good news of our amnio results, I requested for our genetic counselor to send us Baby Z’s chromosome chart (or more accurately, his karyotype chart) so that we may have it as a keepsake.  It arrived today and it is so cool! (See pic below)

The normal human karyotypes contain 22 pairs of chromosomes and one pair of sex chromosomes.  Chromosomes are numbered from largest to smallest, 1 through 22, plus X and Y (which determines gender).  Normal karyotypes for females contain two X chromosomes and are denoted XX; males have both an X and a Y chromosome denoted XY.

As you can see below in the very last pair of chromosomes, Baby Z clearly has a X and a Y chromosome pair, which makes him a very definitive BOY!

I’m no karyotype chart expert, but according to our genetic counselor, here are some other important observations to make from Baby Z’s chart:  Baby Z is negative for Klinefelter’s Syndrome, Down’s Syndrome and Trisomy 13 Syndrome – three of the most common chromosomal disorders.

This is what you would see on his chart if he had any of the above:

i.      Klinefelter’s Syndrome– one or more extra sex chromosomes (i.e., XXY).

ii.    Down’s Syndrome– Trisomy 21, extra chromosome 21.

iii.   Trisomy 13 Syndrome– extra chromosome 13.

Awesome, right?!  The nerd in me is now obsessed with reading up on human genetics…I’m keeping my fingers crossed that Baby Z will inherit my eyes and nose but J’s hair and brains 🙂


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