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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. This type of ...
Bleeding and spotting are common during the luteal phase of the menstrual cycle, and early stages of pregnancy, but are unrelated to implantation. Implantation bleeding occurs between 7 and 14 days after fertilization, [57] and is a small amount of light vaginal bleeding or spotting that can occur in early pregnancy due to the blastocyst ...
[5] [13] Pregnancy is "the presence of an implanted human embryo or fetus in the uterus"; implantation occurs on average 8–9 days after fertilization. [15] An embryo is the term for the developing offspring during the first seven weeks following implantation (i.e. ten weeks' gestational age), after which the term fetus is used until birth. [5]
The popularity of using this measure of pregnancy is largely due to convenience: menstruation is usually noticed, while there is generally no convenient way to discern when fertilization or implantation occurred. Gestational age is contrasted with fertilization age, which takes the date of fertilization as the start date of gestation.
Fertilization was not understood in antiquity. Hippocrates believed that the embryo was the product of male semen and a female factor. But Aristotle held that only male semen gave rise to an embryo, while the female only provided a place for the embryo to develop, [5] a concept he acquired from the preformationist Pythagoras.
The fertilization usually occurs in the fallopian tubes, but can happen in the uterus itself. The zygote then becomes implanted in the lining of the uterus, where it begins the processes of embryogenesis and morphogenesis .
Human embryology is the study of this development during the first eight weeks after fertilization. The normal period of gestation (pregnancy) is about nine months or 36 weeks. The germinal stage refers to the time from fertilization through the development of the early embryo until implantation is completed in the uterus.
Bleeding before childbirth is that which occurs after 24 weeks of pregnancy. [4] Bleeding may be vaginal or less commonly into the abdominal cavity. Bleeding which occurs before 24 weeks is known as early pregnancy bleeding. Causes of bleeding before and during childbirth include cervicitis, placenta previa, placental abruption and uterine rupture.