3 weeks pregnant
Your developing Baby
When you are 3 weeks pregnant, things actually begin to take place. Around mid-cycle (day 14 of a typical 28-day cycle), you ovulate – one of your eggs is swept into your fallopian tube. In the next 12 to 24 hours, that egg can be fertilized if one of 350 million sperm (an average ejaculation) manages to swim all the way to the fallopian tube – from the vagina through the uterus – to penetrate the egg.
Ovum Fertilization and Zygote formation.
The union of egg and sperm at fertilization represents one of the most important processes in biology. Ovulation frees the ovum from the ovary. The ovum is released into the peritoneal cavity, the egg is quickly engulfed by the infundibulum of the fallopian tube. Transport of the egg through the fallopian tube toward the uterus is accomplished by directional movement of ciliary action as well as peristalsis. Fertilization takes place in the Fallopian tube, and it is broadly agreed that fertilization of the ovum must within 24 hours after ovulation. Therefore, sperm must be present in the Fallopian tube at the time of ovum arrival. Almost all pregnancies occur when intercourse occurs during the 2 days preceding or on the day of ovulation.
The steps involved to achieve fertilization are highly complex. The molecular mechanisms that allow passage of sperm between the follicular cells, through the zona pellucida (outer protective covering of Ovum), and into the egg’s cytoplasm leading to the formation of the zygote.
After fertilization in the fallopian tube, the mature ovum becomes a zygote a diploid cell with 46 chromosomes.
The zygote undergoes slow cleavage for 3 days while still within the fallopian tube. As it continues to divide, a solid mulberry-like ball of cells, referred to as the morula, is produced. The morula enters the uterine cavity about 3 days after fertilization. The gradual accumulation of fluid between the cells of the morula results in the formation of the early blastocyst.
Embryos also have been shown to secrete human chorionic gonadotropin (hCG), which may influence endometrial receptivity.
Embryo “hatching” is a critical step toward successful pregnancy as it allows association of the trophoblasts with the epithelial cells of the endometrium and the release of trophoblast-produced hormones into the uterine cavity.
In short, when you are 3 weeks pregnant, fertilization occurs and it become a zygote which continually divides itself and finally attach to the endometrium.
You are 3 weeks pregnant, so start taking certain nutrients, such as folic acid, protein, calcium, and iron, is essential for your baby’s development. A folic acid supplement — which, ideally, you’ve been taking since before you conceived — is particularly important because folic acid helps prevent defects of the neural tube (the structure that gives rise to the brain and spinal cord), which forms very early in pregnancy.
Your intake of protein, which is used to create new tissue, should increase during pregnancy. In addition, calcium is necessary for the development of bones and teeth, so make sure you’re getting a good dose of dairy products, leafy green vegetables, and legumes. Iron is essential during pregnancy as you support the continual increase of your baby’s blood volume. Good sources of iron include red meat, legumes, eggs, and leafy green vegetables.
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