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The huge animals have the longest pregnancies of all mammals. But the 22 month gestation period is not just because of their size. Baby ellies need to stay in the womb that long for their ...
Active and quiet periods for the fetus do not correspond to those of the mother; fetuses are most active from 9 a.m. to 2 p.m. and again from 7 p.m. to 4 a.m. [21] During the last four to six weeks before birth, most of the fetus's kicking and jabbing movements occur while it is sleeping lightly.
The egg is not retained in the body for most of the period of development of the embryo within the egg, which is the main distinction between oviparity and ovoviviparity. [1] Oviparity occurs in all birds, most reptiles, some fishes, and most arthropods. Among mammals, monotremes (four species of echidna, and the platypus) are uniquely oviparous.
This is a collection of lists of mammal gestation period estimated by experts in their fields. The mammals included are only viviparous (marsupials and placentals) as some mammals, which are monotremes (including platypuses and echidnas) lay their eggs.
Obstructed labour, also known as labour dystocia, is the baby not exiting the pelvis because it is physically blocked during childbirth although the uterus contracts normally. [2] Complications for the baby include not getting enough oxygen which may result in death. [ 1 ]
The monotremes branched early from other mammals and do not have the teats seen in most mammals, but they do have mammary glands. The young lick the milk from a mammary patch on the mother's belly. Viviparous mammals are in the subclass Theria; those living today are in the Marsupialia and Placentalia infraclasses.
Strictly, interspecific pregnancy is also distinguished from endoparasitism, where parasite offspring grow inside the organism of another species, not necessarily in the womb. It has no known natural occurrence; however, it can be achieved artificially by transfer of embryos of one species into the womb of another.
The baby's gestational age (number of completed weeks of pregnancy) at the time of birth and the baby's weight (also a measure of growth) influence whether the baby will survive. Another major factor is gender: male infants have a slightly higher risk of dying than female infants, [ 41 ] for which various explanations have been proposed.