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A frank breech (otherwise known as an extended breech) is where the baby's legs are up next to its abdomen, with its knees straight and its feet next to its ears. This is the most common type of breech. [19] A complete breech (or flexed breech) is when the baby appears as though it is sitting crossed-legged with its legs bent at the hips and knees.
It is a manual procedure that is recommended by national guidelines for breech presentation of a pregnancy with a single baby, in order to enable vaginal delivery. [2] [3] It is usually performed late in pregnancy, that is, after 36 gestational weeks, [4] preferably 37 weeks, [5] and can even be performed in the early stages of childbirth. [4]
Presentation of twins in Der Rosengarten ("The Rose Garden"), a German standard medical text for midwives published in 1513. In obstetrics, the presentation of a fetus about to be born specifies which anatomical part of the fetus is leading, that is, is closest to the pelvic inlet of the birth canal.
Type III or concave curves have the greatest mortality (lowest age-specific survival) early in life, with relatively low rates of death (high probability of survival) for those surviving this bottleneck. This type of curve is characteristic of species that produce a large number of offspring (known as r-selected species).
In obstetrics, position is the orientation of the fetus in the womb, identified by the location of the presenting part of the fetus relative to the pelvis of the mother. . Conventionally, it is the position assumed by the fetus before the process of birth, as the fetus assumes various positions and postures during the course of chil
Fecundity selection, also known as fertility selection, is the fitness advantage resulting from selection on traits that increases the number of offspring (i.e. fecundity). [1] Charles Darwin formulated the theory of fecundity selection between 1871 and 1874 to explain the widespread evolution of female-biased sexual size dimorphism (SSD ...
For example, a class of heuristic optimisation algorithms known as genetic algorithms, pioneered by John Henry Holland in the 1970s and expanded upon by David E. Goldberg, [132] identify optimal solutions by simulated reproduction and mutation of a population of solutions defined by an initial probability distribution. [133]
The theory was popular in the 1970s and 1980s, when it was used as a heuristic device, but lost importance in the early 1990s, when it was criticized by several empirical studies. [5] [6] A life-history paradigm has replaced the r/K selection paradigm, but continues to incorporate its important themes as a subset of life history theory. [7]