What's Pregnancy

  

   Pregnancy is a physiological process in which the living offspring of a woman grows in her body, from conception until it can survive outside the mother's body. A woman's pregnancy is said to be pregnant or pregnant. Pregnancy begins with fertilization of the ovum by the sperm that result in the creation of an egg cell which will divide to become an embryo, then a fetus. It continues until birth, or its interruption by a natural or artificial abortion (miscarriage).

    In humans, pregnancy lasts about 39 weeks from fertilization to birth. It is divided into three periods of three months each, commonly called quarters.But for reasons of convention we spoke in weeks of gestation is 41 weeks (corresponding to 39 weeks of gestation over 2 weeks between the first day of last menstruation and fertilization), or even months of pregnancy.

Preimplantation Period At this moment the zygote is a single totipotent stem cell (called cell-egg) with the ability to create an entire organism. Cell division by mitosis is the next process: each cell splits to produce another diploid cell. The zygote divides to produce two smaller cells, called blastomeres, roughly every 20 hours. These cells redivisent about 3 times (16 cells). This cluster of cells, said the morula (because of its appearance, which can bring a blackberry) leaves the fallopian tube and enters the uterus.

Post-implementation Involutes cells are distributed around the blastocoel, a fluid cavity in the middle of cells. The cells become, progressively as their division by mitosis, becoming smaller. This structure includes the zygotic cells and the blastocoel is called the blastocyst. The cells begin to differentiate between cells inside and outside the blastocyst. 24 to 48 hours, the wall of the blastocyst, the zona pellucida, is broken. The exterior of the blastocyst cells begin to secrete an enzyme which erodes the uterine epithelium and creates a site for implantation. The blastocyst also secretes chorionic gonadotropin (HCG), a hormone that stimulates the corpus luteum of the ovary of the mother to produce progesterone, which maintains the lining of the uterus to nourish the embryo. The glands in the uterine lining grow in response to the blastocyst, and the growth of capillaries is stimulated in the region, ensuring the supply of vital nutrients and oxygen to the blastocyst. 

Biological diagnosis of pregnancy is by research blood or urine fraction beta chorionic gonadotropin, better known as beta-HCG. The urine pregnancy tests available in pharmacies offer a qualitative assay of the hormone, their reliability is 90 to 99%. Blood assay, quantitative beta-HCG can be diagnosed with certainty and timing of early pregnancy (the rate of this hormone doubles every 48 hours in early pregnancy)