Tocolytic Agents: Drugs that prevent preterm labor and immature birth by suppressing uterine contractions (TOCOLYSIS). Agents used to delay premature uterine activity include magnesium sulfate, beta-mimetics, oxytocin antagonists, calcium channel inhibitors, and adrenergic beta-receptor agonists. The use of intravenous alcohol as a tocolytic is now obsolete.Tocolysis: Any drug treatment modality designed to inhibit UTERINE CONTRACTION. It is used in pregnant women to arrest PREMATURE LABOR.Uterine Contraction: Contraction of the UTERINE MUSCLE.Obstetric Labor, Premature: Onset of OBSTETRIC LABOR before term (TERM BIRTH) but usually after the FETUS has become viable. In humans, it occurs sometime during the 29th through 38th week of PREGNANCY. TOCOLYSIS inhibits premature labor and can prevent the BIRTH of premature infants (INFANT, PREMATURE).Ritodrine: An adrenergic beta-2 agonist used to control PREMATURE LABOR.Magnesium Sulfate: A small colorless crystal used as an anticonvulsant, a cathartic, and an electrolyte replenisher in the treatment of pre-eclampsia and eclampsia. It causes direct inhibition of action potentials in myometrial muscle cells. Excitation and contraction are uncoupled, which decreases the frequency and force of contractions. (From AMA Drug Evaluations Annual, 1992, p1083)Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Vasotocin: A nonapeptide that contains the ring of OXYTOCIN and the side chain of ARG-VASOPRESSIN with the latter determining the specific recognition of hormone receptors. Vasotocin is the non-mammalian vasopressin-like hormone or antidiuretic hormone regulating water and salt metabolism.Scutellaria baicalensis: A plant species of the genus SCUTELLARIA, family LAMIACEAE, that contains skullcapflavone and is used in CHINESE HERBAL DRUGS.Myometrium: The smooth muscle coat of the uterus, which forms the main mass of the organ.Placenta Previa: Abnormal placentation in which the PLACENTA implants in the lower segment of the UTERUS (the zone of dilation) and may cover part or all of the opening of the CERVIX. It is often associated with serious antepartum bleeding and PREMATURE LABOR.Placenta: A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (CHORIONIC VILLI) derived from TROPHOBLASTS and a maternal portion (DECIDUA) derived from the uterine ENDOMETRIUM. The placenta produces an array of steroid, protein and peptide hormones (PLACENTAL HORMONES).Placentation: The development of the PLACENTA, a highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products between mother and FETUS. The process begins at FERTILIZATION, through the development of CYTOTROPHOBLASTS and SYNCYTIOTROPHOBLASTS, the formation of CHORIONIC VILLI, to the progressive increase in BLOOD VESSELS to support the growing fetus.Placenta Accreta: Abnormal placentation in which all or parts of the PLACENTA are attached directly to the MYOMETRIUM due to a complete or partial absence of DECIDUA. It is associated with POSTPARTUM HEMORRHAGE because of the failure of placental separation.Calcium Channel Blockers: A class of drugs that act by selective inhibition of calcium influx through cellular membranes.Calcium Channels: Voltage-dependent cell membrane glycoproteins selectively permeable to calcium ions. They are categorized as L-, T-, N-, P-, Q-, and R-types based on the activation and inactivation kinetics, ion specificity, and sensitivity to drugs and toxins. The L- and T-types are present throughout the cardiovascular and central nervous systems and the N-, P-, Q-, & R-types are located in neuronal tissue.Nifedipine: A potent vasodilator agent with calcium antagonistic action. It is a useful anti-anginal agent that also lowers blood pressure.Uterine Monitoring: Measurement or recording of contraction activity of the uterine muscle. It is used to determine progress of LABOR, OBSTETRIC and assess status of pregnancy. It is also used in conjunction with FETAL MONITORING to determine fetal response to stress of maternal uterine contractions.Labor, Obstetric: The repetitive uterine contraction during childbirth which is associated with the progressive dilation of the uterine cervix (CERVIX UTERI). Successful labor results in the expulsion of the FETUS and PLACENTA. Obstetric labor can be spontaneous or induced (LABOR, INDUCED).Labor, Induced: Artificially induced UTERINE CONTRACTION. Generally, LABOR, OBSTETRIC is induced with the intent to cause delivery of the fetus and termination of pregnancy.Blood Pressure: PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.Hypertension: Persistently high systemic arterial BLOOD PRESSURE. Based on multiple readings (BLOOD PRESSURE DETERMINATION), hypertension is currently defined as when SYSTOLIC PRESSURE is consistently greater than 140 mm Hg or when DIASTOLIC PRESSURE is consistently 90 mm Hg or more.Tonometry, Ocular: Measurement of ocular tension (INTRAOCULAR PRESSURE) with a tonometer. (Cline, et al., Dictionary of Visual Science, 4th ed)Antihypertensive Agents: Drugs used in the treatment of acute or chronic vascular HYPERTENSION regardless of pharmacological mechanism. Among the antihypertensive agents are DIURETICS; (especially DIURETICS, THIAZIDE); ADRENERGIC BETA-ANTAGONISTS; ADRENERGIC ALPHA-ANTAGONISTS; ANGIOTENSIN-CONVERTING ENZYME INHIBITORS; CALCIUM CHANNEL BLOCKERS; GANGLIONIC BLOCKERS; and VASODILATOR AGENTS.Amlodipine: A long-acting dihydropyridine calcium channel blocker. It is effective in the treatment of ANGINA PECTORIS and HYPERTENSION.Blood Pressure Determination: Techniques for measuring blood pressure.Pregnancy, Twin: The condition of carrying TWINS simultaneously.Twins: Two individuals derived from two FETUSES that were fertilized at or about the same time, developed in the UTERUS simultaneously, and born to the same mother. Twins are either monozygotic (TWINS, MONOZYGOTIC) or dizygotic (TWINS, DIZYGOTIC).Premature Birth: CHILDBIRTH before 37 weeks of PREGNANCY (259 days from the first day of the mother's last menstrual period, or 245 days after FERTILIZATION).Diseases in Twins: Disorders affecting TWINS, one or both, at any age.Middle Cerebral Artery: The largest of the cerebral arteries. It trifurcates into temporal, frontal, and parietal branches supplying blood to most of the parenchyma of these lobes in the CEREBRAL CORTEX. These are the areas involved in motor, sensory, and speech activities.Magnesium Deficiency: A nutritional condition produced by a deficiency of magnesium in the diet, characterized by anorexia, nausea, vomiting, lethargy, and weakness. Symptoms are paresthesias, muscle cramps, irritability, decreased attention span, and mental confusion, possibly requiring months to appear. Deficiency of body magnesium can exist even when serum values are normal. In addition, magnesium deficiency may be organ-selective, since certain tissues become deficient before others. (Harrison's Principles of Internal Medicine, 12th ed, p1936)Magnesium: A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.Physiology: The biological science concerned with the life-supporting properties, functions, and processes of living organisms or their parts.Educational Measurement: The assessing of academic or educational achievement. It includes all aspects of testing and test construction.Anatomy: A branch of biology dealing with the structure of organisms.Computer-Assisted Instruction: A self-learning technique, usually online, involving interaction of the student with programmed instructional materials.Teaching: The educational process of instructing.Codon, Initiator: A codon that directs initiation of protein translation (TRANSLATION, GENETIC) by stimulating the binding of initiator tRNA (RNA, TRANSFER, MET). In prokaryotes, the codons AUG or GUG can act as initiators while in eukaryotes, AUG is the only initiator codon.Curriculum: A course of study offered by an educational institution.Veterinary Medicine: The medical science concerned with the prevention, diagnosis, and treatment of diseases in animals.Cesarean Section: Extraction of the FETUS by means of abdominal HYSTEROTOMY.Education, Veterinary: Use for general articles concerning veterinary medical education.OregonInformation Centers: Facilities for collecting and organizing information. They may be specialized by subject field, type of source material, persons served, location, or type of services.National Health Planning Information Center (U.S.): A center in the HEALTH RESOURCES ADMINISTRATION Division of Planning Methods and Technology which provides access to current information on health planning and resources development.Beverages: Liquids that are suitable for drinking. (From Merriam Webster Collegiate Dictionary, 10th ed)Poison Control Centers: Facilities which provide information concerning poisons and treatment of poisoning in emergencies.Micronutrients: Essential dietary elements or organic compounds that are required in only small quantities for normal physiologic processes to occur.Diet: Regular course of eating and drinking adopted by a person or animal.Tablets: Solid dosage forms, of varying weight, size, and shape, which may be molded or compressed, and which contain a medicinal substance in pure or diluted form. (Dorland, 28th ed)Drugs, Generic: Drugs whose drug name is not protected by a trademark. They may be manufactured by several companies.Terminology as Topic: The terms, expressions, designations, or symbols used in a particular science, discipline, or specialized subject area.Drug Prescriptions: Directions written for the obtaining and use of DRUGS.Capsules: Hard or soft soluble containers used for the oral administration of medicine.Tablets, Enteric-Coated: Tablets coated with material that delays release of the medication until after they leave the stomach. (Dorland, 28th ed)Marketing: Activity involved in transfer of goods from producer to consumer or in the exchange of services.