Pregnancy Calendar
The First Trimester
This is what is going on in your body throughout the first trimester on your pregnancy calendar:
Pregnancy Calendar: Conception to Embryo
Your baby is conceived approximately 14 days after the first day of your last period. When figuring out your due date, your doctor includes those first two weeks in the 40- week gestation term even though you weren't officially pregnant at that time.
During conception, your egg hooks up with your man's sperm to form a zygote, which is just one tiny cell at this point. Despite its small size, chromosomes within the zygote are responsible for eye color, hair color, height and other features. Once it is fertilized, the little zygote will move on down your fallopian tube to your uterus. At this point, your zygote becomes known as a blastocyte.
Once it lands in your uterus, the blastocyte embeds itself into the your uterine wall. This usually happens around 7-9 days after conception. Once the blastocyte is a part of your uterine wall, the placenta starts forming. By now you may have noticed that you skipped a period and begun celebrating your pregnancy!
Next your blastocyte becomes an embryo! Development of the brain, organs and spine begins quickly, and the embryo's heart and circulatory system start developing before you are even six weeks pregnant. Although you can't hear the baby's heart yet, it may be visible during an ultrasound. The heart will start beating as soon as the baby's circulatory system completes its circuit.
Pregnancy Calendar: Week 6
By the halfway point of your first trimester, the baby is about 1/8 inch long. Here's what else is happening: - neural tube for the brain and spine has nearly closed - baby's heart is beating - mouth, ears and other facial features are starting to form - tissue is growing for the ribs and muscles - arms and legs are preparing to grow - baby's skull not solid, but canals and channels that circulate spinal fluid are developed.
Pregnancy Calendar: Week 8
Now you can see the baby's fingers and toes, although they are still webbed. The ears, eyelids, lips and nose are more clearly defined, as are the joints at the baby's ankles, elbows and wrists.
Pregnancy Calendar: Week 9
By week 9, your baby has grown to about one inch long and their head is tucked down into their chest. At this point the embryonic tail is disappearing and hair follicles, nipples and reproductive organs are starting to develop. Other organs, like the gallbladder and pancreas, have already been formed.
Pregnancy Calendar: Weeks 10-12
Toward the end of the first trimester, the embryonic tail has completely disappeared as has the webbing between the fingers and toes. Vital organs are developed, bones have been formed and the brain is already beginning to work. You can also see the baby's eyelids and outer ears, and tooth buds are being developed.
Pregnancy Calendar: The First Trimester Ends
At the end of the first trimester, your baby officially becomes a fetus. The baby is now approximately 3 inches long and weighs just under an ounce. Fingernails and facial features are now more apparent, and genitals are becoming more obvious. The placenta is kicked into overdrive now to supply all of the nutrients that will be needed by your growing baby in the second and third trimesters.
| Next >> |