The
Stages Of Pregnancy - The First Trimester
by Janet Hart
Here is what happens inside your womb during the first trimester: Conception actually takes place about two weeks after your menstrual cycle starts. Although the 2 week period of time during and right after menstruation is counted into your 40 week gestation term, you are not actually pregnant during that time, but your doctor will calculate your due date, based on the start date of your last period. The sperm and egg get together to form a tiny one-celled being (a zygote). The chromosomes in the zygote dictate gender, eye and hair color, height and features. After fertilization takes place, the zygote will begin to travel down the fallopian tube and into the uterus. Your little zygote is now called a 'blastocyte', a not so pretty name for your new baby. When the blastocyte reaches the uterus it attaches itself to the uterine wall (some time between day 7 and day 9 following conception) and the placenta begins to form. If you have been paying attention to your cycles, you may already be celebrating a positive pregnancy test by now! At this point, your child is officially an 'embryo' with a developing brain, spine, and organs. Not quite half way through the first trimester, your baby's heart and circulatory system will develop quickly. You won't be able to hear your baby's heart beat yet but your doctor may see the first signs of a heartbeat during an ultrasound test. Once the circulatory system has completed its circuit, the heart will beat and the first organ in your baby's body will be functional. In week 6, your baby is about 8th of an inch in size and the neural tube for his/her brain and spine is nearly closed. The heart is beating and basic facial features are forming, including the mouth and the ears. The tissue for ribs and muscles is developing and the 'buds' are in place to grow arms and legs. Her skull is not solid yet but she has formed all the canals and channels she will need to circulate spinal fluid. During week 8, fingers and toes are now visible, though they are still webbed. There is increased definition in the joints (ankles, elbows and wrists) and his ears lips, nose and eyelids are more defined. By the 9th week, your baby is just about an inch long, and the embryonic 'tail' at the bottom of the spine is shrinking fast. Her head is tucked down on her chest, and she has started to form nipples, reproductive organs and hair follicles. Organs like the pancreas and gallbladder have also developed. Nearly at the end of the first trimester, your baby has developed his vital organs, lost his embryonic tail and the webbing between his fingers and toes. His bones are form and his brain is cranking out neurons. His eyelids and his outer ears are formed and he is starting to grow 'tooth buds' Congratulations!
You now have a fetus! Genitalia is becoming apparent, and your placenta
is working overtime to supply the nutrients for her growth during
the 2nd and 3rd trimester.
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