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Implantation bleeding. "Implantation bleeding is thought to be light bleeding that occurs about 10 days after ovulation," says Washington, D.C.-based ob-gyn Dr. Cordelia Nwankwo .
The implantation is assisted by hydrolytic enzymes that erode the epithelium. The syncytiotrophoblast also produces human chorionic gonadotropin, a hormone that stimulates the release of progesterone from the corpus luteum. Progesterone enriches the uterus with a thick lining of blood vessels and capillaries so that it can oxygenate and sustain ...
Implantation, also known as nidation, [1] is the stage in the mammalian embryonic development in which the blastocyst hatches, attaches, adheres, and invades into the endometrium of the female's uterus. [2] Implantation is the first stage of gestation, and, when successful, the female is considered to be pregnant. [3]
The germinal stage refers to the time from fertilization, through the development of the early embryo, up until implantation. The germinal stage is over at about 10 days of gestation. [2] The zygote contains a full complement of genetic material with all the biological characteristics of a single human being, and develops into the embryo.
Adequate nutrition is needed for a healthy fetus. Mothers who gain less than 20 pounds during pregnancy are at increased risk for having a preterm or low birth weight infant. [51] Iron and iodine are especially important during prenatal development. Mothers who are deficient in iron are at risk for having a preterm or low birth weight infant. [52]
For example, early pregnancy factor (EPF) can be detected in blood within 48 hours of fertilization, rather than after implantation. [32] However, its reliable use as a pregnancy test remains unclear as studies have shown its presence in physiological situations besides pregnancy, and its application to humans remains limited. [33]
For most species, the amount a fetus grows before birth determines the length of the gestation period. Smaller species normally have a shorter gestation period than larger animals. [2] For example, a cat's gestation normally takes 58–65 days while an elephant's takes nearly 2 years (21 months). [3]
This is an accepted version of this page This is the latest accepted revision, reviewed on 21 December 2024. Procreative biological processes of humanity Part of a series on Sex Biological terms Sexual dimorphism Sexual differentiation Feminization Virilization Sex-determination system XY XO ZW ZO Temperature-dependent Haplodiploidy Heterogametic sex Homogametic sex Sex chromosome X chromosome ...