3 Weeks Pregnant...
You're actually considered to be 3 weeks pregnant, even though your just now getting pregnant.
Once the egg is fertilized, the sperm's nucleus (head of the sperm) will fuse with the egg and will combine their genetic information.
The fertilized egg contains 46 chromosomes 23 from you and 23 from daddy. If the sperm that penetrates the egg is an 'X' chromosome the baby will be a girl, but if the sperm is a 'Y' chromosome then the baby will be a boy.
Your baby's gender is determined at conception along with the hair color, eye color and physical characteristics.
During this time the baby is called a 'zygote'. It will take about 3-4 days for the baby to make it's way from the fallopian tube down into the uterus for implantation.
Cell multiplication is happening at a remarkably quick rate. As the baby makes it's way down into the uterus
it will divide into 16 identical cells. Your little zygote will spend the next 7-10 days dividing and multiplying as they slowly drop down into the uterus, where it's now called a 'morula'.
A day or two later, it will start to embed into the lining of your uterus, continuing its miraculous growth and transformation.
If separation into identical twins occurs, 2/3 of the time it will happen between days 5 and 9. If it happens after day 9, there is a significant risk of the twins being conjoined.
Your baby is the size of the head of a pin and during this time that your 3 weeks pregnant the developing baby is just a little ball of cells that's now called a blastocyst measuring about 0.1-0.2 mm or 0.006 inchs: It has an inner cell mass that will become the embryo itself, a fluid-filled cavity that will become the amniotic sac, and an outer cell mass that will become the placenta, the organ that delivers oxygen and nutrients to your baby and carries away his waste products.
Once the baby implants into the uterus, the placenta starts producing the pregnancy hormone hCG. This is the hormone that will turn the pregnancy test positive. You should be able to get this result by the end of the week.
Meanwhile, amniotic fluid is beginning to collect around your baby in the space that will become the amniotic sac. This fluid will cushion your baby in the weeks and months ahead.
About 18 days after fertilization, the embryo has divided to form most of the tissue it will need. Your little, itty, bitty one is shaped like a pear, where the head area is larger than the tail. The baby's nervous system is one of the first organic systems to grow. It begins growing in a concave area known as the neural groove.
The best part of this week is that somewhere around the 21st day, your incredible little baby will have a beating heart, even though the heart chambers and valves will not be completely developed for another couple of weeks.
Now that's a lot going on and your only 3 weeks pregnant!!
Can you believe it?!
You're going to be someones Mommy soon!