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Fetal viability is the ability of a human fetus to survive outside the uterus. Viability depends upon factors such as birth weight, gestational age, and the availability of advanced medical care. In low-income countries, more than 90% of extremely preterm newborns (less than 28 weeks gestational age) die due to a lack of said medical care; in ...
Obstetric ultrasonography, or prenatal ultrasound, is the use of medical ultrasonography in pregnancy, in which sound waves are used to create real-time visual images of the developing embryo or fetus in the uterus (womb). The procedure is a standard part of prenatal care in many countries, as it can provide a variety of information about the ...
Gestational age. In obstetrics, gestational age is a measure of the age of a pregnancy taken from the beginning of the woman's last menstrual period (LMP), [ 1] or the corresponding age of the gestation as estimated by a more accurate method, if available. Such methods include adding 14 days to a known duration since fertilization (as is ...
Head hair becomes coarse and thicker. Birth is imminent and occurs around the 38th week after fertilization. The fetus is considered full-term between weeks 37 and 40 when it is sufficiently developed for life outside the uterus. [ 14][ 15] It may be 48 to 53 cm (19 to 21 in) in length when born.
The second trimester is defined as starting, between the beginning of week 13 (12 weeks +0 days of GA) [4] and beginning of week 15 (14 weeks + 0 days of GA). [36] It ends at the end of week 27 (26 weeks + 6 days of GA) [ 36 ] or end of week 28 (27 weeks + 6 days of GA).
Gestational age: 3 weeks and 0 days until 3 weeks and 6 days old. 22–28 days from last menstruation. Embryonic age: Week nr 2. 1 week old. 8–14 days from fertilization. Trophoblast cells surrounding the embryonic cells proliferate and invade deeper into the uterine lining. They will eventually form the placenta and embryonic membranes.
Embryonic development in the human, covers the first eight weeks of development; at the beginning of the ninth week the embryo is termed a fetus. The eight weeks have 23 stages. 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 ...
By about week 21, the fetus begins to develop a regular schedule of movement. [17] The startle reflex is present in half of all fetuses by week 24 and in all fetuses by week 28. [19] Movement is restricted around this time because the fetus has grown so large it has little space for kicking or changing body position. [20]