Multiple Birth Offspring
Reproductive Techniques, Assisted
The age of the mother in PREGNANCY.
CHILDBIRTH before 37 weeks of PREGNANCY (259 days from the first day of the mother's last menstrual period, or 245 days after FERTILIZATION).
Infant, Low Birth Weight
The transfer of mammalian embryos from an in vivo or in vitro environment to a suitable host to improve pregnancy or gestational outcome in human or animal. In human fertility treatment programs, preimplantation embryos ranging from the 4-cell stage to the blastocyst stage are transferred to the uterine cavity between 3-5 days after FERTILIZATION IN VITRO.
The age of the conceptus, beginning from the time of FERTILIZATION. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last MENSTRUATION which is about 2 weeks before OVULATION and fertilization.
Fertilization in Vitro
Prenatal Exposure Delayed Effects
Inability to reproduce after a specified period of unprotected intercourse. Reproductive sterility is permanent infertility.
Pregnancy Reduction, Multifetal
Selective abortion of one or more embryos or fetuses in a multiple gestation pregnancy. The usual goal is to improve the outcome for the remaining embryos or fetuses.
A family of snakes comprising the boas, anacondas, and pythons. They occupy a variety of habitats through the tropics and subtropics and are arboreal, aquatic or fossorial (burrowing). Some are oviparous, others ovoviviparous. Contrary to popular opinion, they do not crush the bones of their victims: their coils exert enough pressure to stop a prey's breathing, thus suffocating it. There are five subfamilies: Boinae, Bolyerinae, Erycinae, Pythoninae, and Tropidophiinae. (Goin, Goin, and Zug, Introduction to Herpetology, 3d ed, p315-320)
Alligators and Crocodiles
Large, long-tailed reptiles, including caimans, of the order Loricata.
The doctrines and policies of the Nazis or the National Social German Workers party, which ruled Germany under Adolf Hitler from 1933-1945. These doctrines and policies included racist nationalism, expansionism, and state control of the economy. (from Columbia Encyclopedia, 6th ed. and American Heritage College Dictionary, 3d ed.)
Diseases in Twins
Disorders affecting TWINS, one or both, at any age.
Performing the role of a parent by care-giving, nurturance, and protection of the child by a natural or substitute parent. The parent supports the child by exercising authority and through consistent, empathic, appropriate behavior in response to the child's needs. PARENTING differs from CHILD REARING in that in child rearing the emphasis is on the act of training or bringing up the children and the interaction between the parent and child, while parenting emphasizes the responsibility and qualities of exemplary behavior of the parent.
Encyclopedias as Topic
The condition of carrying TWINS simultaneously.
A vitamin that includes both CHOLECALCIFEROLS and ERGOCALCIFEROLS, which have the common effect of preventing or curing RICKETS in animals. It can also be viewed as a hormone since it can be formed in SKIN by action of ULTRAVIOLET RAYS upon the precursors, 7-dehydrocholesterol and ERGOSTEROL, and acts on VITAMIN D RECEPTORS to regulate CALCIUM in opposition to PARATHYROID HORMONE.
Vitamin D Deficiency
A nutritional condition produced by a deficiency of VITAMIN D in the diet, insufficient production of vitamin D in the skin, inadequate absorption of vitamin D from the diet, or abnormal conversion of vitamin D to its bioactive metabolites. It is manifested clinically as RICKETS in children and OSTEOMALACIA in adults. (From Cecil Textbook of Medicine, 19th ed, p1406)
That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-UV or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-UV or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants.
Disorders caused by interruption of BONE MINERALIZATION manifesting as OSTEOMALACIA in adults and characteristic deformities in infancy and childhood due to disturbances in normal BONE FORMATION. The mineralization process may be interrupted by disruption of VITAMIN D; PHOSPHORUS; or CALCIUM homeostasis, resulting from dietary deficiencies, or acquired, or inherited metabolic, or hormonal disturbances.