Wednesday, September 14

5 Weeks Postconception

When I called and told one of my dear friends that I was pregnant, she was almost as I excited and curious as I was to know exactly what is happening with our baby at that moment. I, of course, find this to be absolutely fascinating. I thought that some of my readers might find these changes interesting too. If you don’t, don’t worry, I’ll be back to talking about other things soon.


While I am considered seven weeks pregnant, our baby was conceived just five weeks ago. Development during this time has been taking place very rapidly. For the first two weeks after conception, our baby was considered a zygote, which is marked by rapid cell division. During the third week our baby implanted into my uterine wall which brings it into the embryonic stage of development, which will last for six weeks. The embryonic stage of development is when the major development of all the organs and bodily systems take place. This is also the most delicate stage of development in that it is when major structural abnormalities occur.

A baby’s central nervous system is the first thing to develop. At this point our baby has a tiny little brain and a neural tube as well as the nerves connecting to the other developing systems. I’ve been really good about getting enough folic acid so his/her neural tube should have closed last week. This week the cerebral hemispheres are growing and little cavities and passageways for the flow of spinal fluid should be forming.

A baby’s heart and circulatory system also starts to develop very soon after implantation, with the first heartbeats happening 21-22 days after conception. Last week, the heart was developed enough to have a regular beat and to pump blood through main blood vessels. By this time, it has divided into left and right heart chambers, bulging from the body with every beat. His/her umbilical cord is now clearly visible and circulatory system is independent of mine. Our baby receives oxygen and nutrients it needs through placental exchange. The amniotic sac has formed and our baby is now floating in a cushion of amniotic fluid.


Artist rendering courtesy of Mayo Clinic Guide to a Healthy Pregnancy

Last week, both the optic nerve and the inner ears began to form. This week a little more facial definition is happening with a little perforation for a mouth, nostrils and ear canals. The color in the eye’s irises in now visible and the lenses of the eyes are forming. His/her inner ear is now connecting to the middle ear and to the rest of the world.

The beginning of both the respiratory and the digestive system began to form last week. By now, the primary bronchi of the lungs should be present. At this point, part of the intestines bulge into the umbilical cord and the intestines are developing further. The appendix should be present, and so should the pancreas and the liver.

Last week, small buds that will grow into the baby’s arms and legs became visible. This week, these buds will take on a little more definition and form shoulders and little paddles that will later become his/her hands and feet.

Most of our baby’s development is taking place in and close to the head, so just about half of the baby’s total length is made up of head. This week our baby is expected to more than double in size from around 5 mm to approximately 12 mm, averaging around the size of the eraser at the end of a pencil, or 1/3 or an inch.

My sources:

Curtis, Glade B. and Judith Schuler. Your Pregnancy Week by week, 4th ed. Tucson: Fisher Books, 2000.
This book was passed along to me by my sister-in-law (the mother of my adorable niece and nephew). It pays a attention to the hormonal irrational fears and the aches and pains of pregnancy and is nice to have around.

Harms, Robert W., ed. Mayo Clinic Guide to a Healthy Pregnancy. New York: HarperCollins, 2004.
This is the most up to date and no nonsense pregnancy book I could find, to help my imagination from straying too far.

Siegler, Robert, Judy Deloache, and Nancy Eisenberg. How Children Develop. New York: Worth, 2003.
This is the textbook from the enlightening Developmental Psychology class that I’m so glad that I took last autumn.

9 comments:

Pearl said...

It's pretty amazing that you can follow along and know so much about what is going on while the scale in mm is so tiny.

Lora said...

There is so much information out there it's a little overwhelming. I guess research done to help prevent birth defects is mainly to thank.

tapestrygirl said...

Awwwwwwwwwwwwwww!

Julie said...

I remember those days! I was so fortunate during my first pregnancy to work in Labor and Delivery throughout my whole term. We played with the ultrasound when it was slow, and listened to the baby's heartbeat, etc.

I also got to learn sooo much about pregnancy, working alongside all the midwives and ob/gyns, and helped deliver hundreds of babies--and I enjoyed every minute of it. :)

When you have the baby, it's a happy occasion (obviously!), but in a way it's kind of sad too. You lose that connection of that baby living inside you. So savor these days (and all the changed that come with them), because even though it seems like you will be pregnant forever, it will be over before you know it.

Ok, done rambling! Congrats again, I'm soo happy for you!

Julie said...

oops, should be "changes"

oceanskies79 said...

Thanks for sharing. Every bit of the development is a process involving love.

Contemplative Activist said...

I wish I'd popped by earlier - so a slightly belated CONGRATULATIONS from me!

Cute picture - isn't it crazy how a little life develops inside you from a teensy-weensy thing into a baby. Wow.

Princess Jami said...

My congratulations are slightly more belated than contemplative activist, Lori. Oops. :-) So, CONGRATS! This is terrific news. I'll be looking forward to more updates.

Catez said...

The actual size picture is amazing - so tiny.