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Prenatal methamphetamine exposure
Prenatal methamphetamine exposure (PME) is the exposure of a prenatal fetus to methamphetamine when a woman uses the drug during her pregnancy. Methamphetamine (MA) has shown increasing popularity in the past two decades among women of childbearing age. Methamphetamine is second only to cannabis as the most widely used illegal drug, which may be because it is relatively cheap and easy to manufacture. Yet, to this date, the effects of PME on the developing fetus have not been well characterized and even less is known regarding the effects on development in childhood. Although few studies have established a pattern of MA use in pregnant users, it is important that researchers seek to determine this pattern to examine a possible dose-response relationship between MA use and neonatal outcomes. The recent increase in MA use in the United States, particularly in the South and Midwest, highlights the need for a better understanding of the short-term and long-term effects of MA use during pregnancy upon newborns and young children.〔
The effects of MA on a fetus are often compared to those of cocaine, but the neurotoxic effects of MA may be greater than those of cocaine. This may be due to MA’s ability to remain active in the body for longer and its greater capacity to mimic the effects of neurotransmitters in the brain. Studying the effects of PME is often complicated by the fact that there are numerous elements that are associated with MA use, which in turn may be associated with adverse effects in exposed infants. For example, depression is highly correlated with MA use, which is in turn associated with less spousal support, increased anxiety, less prenatal care, malnourishment, preterm labor, and more stressors in the areas of work, health, and environment.〔 A study done in New Zealand found that mothers referred to treatment centers for MA use were often multiple drug abusers, had a history of not keeping doctors appointments, and displayed mental health problems including psychotic behavior. This makes it incredibly difficult for researchers to tease apart the effects due to the drug itself versus the other influential lifestyle factors.
==Pathophysiology==
Methamphetamine (MA), a potent central nervous system stimulant, causes a rush of dopamine, norepinephrine, and serotonin release in the brain when ingested.〔 Street methamphetamine is referred to by many names, such as “speed,” “meth,” and “chalk”. The drug can be injected, smoked, snorted, and even taken by oral or anal routes.〔 The neurotransmitter release from MA ingestion (especially dopamine) leads to feelings of euphoria, decreased appetite and fatigue, and increased alertness, wellbeing, and exhilaration.〔 More specifically, MA mechanism of action is to stimulate the release of dopamine into the synaptic cleft while preventing the reuptake of dopamine and norephinephrine.〔 Long-lasting functional impairments in the monoamine system are likely to result from long-term abuse of MA.〔
It is known that MA readily crosses the placenta that feeds the developing fetus, yet the ways in which the drug affects the fetus are not fully understood.〔 MA may exert its effects on the fetus directly by transfer through the placenta or indirectly by altering the fetal environment.〔 MA has vasoconstrictive effects, resulting in decreased uteroplacental blood flow, elevated fetal blood pressure, and fetal hypoxia. These effects often work together to result in prenatal strokes, heart or other major organ damage in the developing fetus.〔 These vasoconstrictive side effects can also have anorexic effects on the mother, which can hinder intrauterine growth.〔 Studies done with pregnant rodents have found that prenatal MA exposure results in altered neural circuitry, both structurally and functionally.〔 These impairments can lead to later behavioral problems since the neural circuitry is responsible for maintaining functions such as arousal, regulation and reactivity to stress.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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