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Read the Pregnancy & Lactation FAQ
by Loretta P. Finnegan, MD
The use of psychoactive drugs during pregnancy can place at risk the expectant mother, fetus, newborn and child. This represents a problem affecting all socioeconomic and ethnic classes, in countries throughout the world, and the associated costs are borne by the entire society.
In the United States in 1992, the National Institute on Drug Abuse estimated that of some 4 million births, one or more illicit drugs were taken during pregnancy by 5.5 percent, or 221,000, of the mothers. The incidence of use varies with geographic location, socioeconomic status and educational level.
Drug dependence during pregnancy is a complex biopsychosocial problem that presents multiple challenges. When assessing the impact of addiction on the pregnant woman and, ultimately, her infant, one must consider the environmental problems they face. The cycle of addiction not only includes illicit and licit drug use and its direct concomitants, but also family dysfunction, physical and sexual abuse, social issues, legal problems and educational deficits, unemployment, etc.
Because of this extremely high-risk environment, and the pregnant drug-dependent woman's frequent lack of prenatal care, the infant is predisposed to a host of neonatal problems in addition to the pharmacologic effect of the substance used. Many are due to low birth weight and prematurity – e.g., asphyxia neonatorum, intracranial hemorrhage, respiratory distress syndrome, intrauterine growth retardation, hypoglycemia, hypocalcemia, septicemia and hyperbilirubinemia.
For injecting drug users, the most frequently encountered medical problems include: infections (cellulitis, hepatitis, pneumonia, bacterial endocarditis, sexually transmitted diseases and HIV), anemia, thombocytopenia, thrombophlebitis, overdose and multiple injuries from trauma. In women using heroin, fetal wastage can result from spontaneous abortion, intrauterine death, amnionitis, chorioamnionitis, gestational diabetes, and premature rupture of the membranes and septicemia. Placental disorders that may occur include abruption, infarction and insufficiency. Lack of prenatal care also predisposes to pre-eclampsia and eclampsia. The most commonly seen obstetrical complications are preterm birth and intrauterine growth retardation. In addition, heroin-addicted women are at heightened risk of hemorrhage following delivery.
For three decades, methadone maintenance has been recommended for opioid dependence in pregnancy. It has been demonstrated consistently that treatment with methadone, delivered with comprehensive services that include prenatal care, can reduce significantly the incidence of obstetric and fetal complications and neonatal morbidity and mortality. Methadone can be taken by mouth, prevents the onset of opioid abstinence syndrome for 24-36 hours, reduces or eliminates drug craving, and blocks (through the development of tolerance) the euphoric effects if supplemental narcotics are taken. Methadone maintenance therapy for the pregnant woman also prevents erratic maternal opioid levels and protects the fetus from repeated episodes of withdrawal, decreases the woman's risk of HIV infection and hepatitis, and reduces behaviors often associated with drug-seeking, such as prostitution and the risk of sexually transmitted diseases. As pregnancy progresses, some methadone maintained women require elevations of the dose to maintain the same plasma level. Higher doses of methadone in the third trimester have been associated with improved fetal growth and longer duration of gestation; therefore, more liberal methadone dosing in pregnancy may improve initial and long-term neonatal outcome.
Not all infants born to opioid-dependent mothers – whether on heroin, methadone or other narcotics – show signs of withdrawal; literature reports indicate an incidence between 60 to 90 %. This variation is not surprising, because the multiple biochemical and physiologic processes governing withdrawal, and their interactions, are still poorly understood. Polydrug abuse, erratic drug ingestion, vague and inaccurate maternal histories and methods of analyzing body fluids to detect prenatal exposure – all these factors preclude definitive statements regarding the type, time of onset, duration and severity of withdrawal.
Methadone-exposed infants generally are reported to have a higher incidence and more prolonged duration of abstinence than those whose mothers used heroin. Comparison studies, however, involve unknown dosage of heroin; often lump together clinically prescribed, constant dosage of methadone with intermittent self-administration; and fail to take into account varying duration of methadone maintenance prior to delivery. At any rate, the relationship between methadone dose and neonatal abstinence severity has not been clearly established. The bottom line: there is no rationale for lowering doses during pregnancy. To do so may be expected to promote illicit drug use and increase the risk to the fetus.
Narcotic abstinence syndrome is a generalized disorder characterized by signs of hyperirritability of the central nervous system, gastrointestinal dysfunction, respiratory distress and vague autonomic nervous system symptoms that include yawning, sneezing, mottling and increased temperature. Initially infants develop mild, high frequency, low amplitude tremors that progress in severity. A high-pitched cry, increased muscle tone, irritability, increased deep tendon reflexes and an exaggerated Moro reflex are all characteristic of the syndrome at this stage. The rooting reflex is increased and sucking of fists or thumbs is common, yet infants show great difficulty with feeding and regurgitate frequently. The feeding difficulty results from an uncoordinated and ineffectual sucking reflex. Infants may also develop loose stools, and therefore are susceptible to dehydration and electrolyte imbalance.
Time of onset of signs of withdrawal is variable. At delivery, serum and tissue levels of in-utero drugs begin to fall. The newborn continues to metabolize the drug(s), and abstinence signs occur when critically low tissue levels have been reached. Because of the variation in time of onset and in degree of severity, a spectrum of abstinence patterns may be observed. Withdrawal may be mild and transient, delayed in onset, or characterized by a stepwise increase in severity. It may be present intermittently, or have a biphasic course that includes acute withdrawal followed by improvement, and then an exacerbation once again. More severe symptoms seem to occur in infants whose mothers have taken large amounts of drugs for a long time. The maturity of the infant's metabolic and excretory mechanisms also plays an important role, since preterm infants generally excrete the prenatal drug(s) more slowly and seem to show a less vigorous onset of withdrawal. Duration of withdrawal signs may vary from a few days to weeks or even months.
A significant advantage of treating the pregnant heroin addict with methadone is that breast feeding can be encouraged if the mother is not abusing other drugs. Such a small amount of methadone appears in the breast milk that it is not even adequate treatment for the newborn showing signs of abstinence. The immunologic and bonding benefits of breast feeding, of course, are particularly valuable in the opiate-dependent mother. On the other hand, if the mother is abusing drugs, or if there are infections such as HIV or hepatitis, breast feeding is contraindicated.
We have made great strides in the medical care of newborns who experience drug exposure in-utero. And yet, specialized treatment resources for childbearing women and their children are generally lacking and, sadly, many medical professionals do not see this as an important area for their research and treatment efforts. Addiction is a chronic, relapsing disorder which encompasses every system in the human body. The numerous issues to be addressed acutely, and the chronic relapsing nature of addiction, make the clinician's task appear almost overwhelming when contemplating the optimal care of the maternal-infant dyad. But we know that intergenerational transmission of addiction and its multiple problems, including HIV, are inevitable if methadone maintenance with comprehensive services are not provided for the opioid dependent women and her child. While (as with most medical conditions) there is no panacea in response to maternal heroin dependence, there is a great deal that can be done to prevent the physical, psychological and social disabilities resulting from this most pervasive disorder, which destroys not only individuals, but the fiber of our society - the family.
The above is taken from a presentation at the International Conference on Drug Dependence, Maternity and Childhood held in Turin, Italy on November 13-14, 2000.
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Source: OB GYN News – Section No. 16, Vol 36; Pg 10 – ISSN:0029-7437 (August 15,2001) United States – Los Angeles
Dr. Peter Selby presented at the annual meeting of the American Society of Addiction Medicine, 2001, a study demonstrating that babies born to women who take relatively higher doses of methadone during the third trimester are no more likely to experience withdrawal than those whose mothers receive a lesser dosage.
The findings were based on a careful review of records of 53 women who delivered at St. Joseph's Health Centre in Toronto between 1994 and 2000. Of these, 26 received a mean daily dose of 64mg methadone and 27 received a mean daily dose of 132mg. The infants of the two cohorts had no significant differences in birth weight, length of hospital stay, or incidence or duration of neonatal withdrawal.
Methadone maintenance is the standard care for opioid addicted women during pregnancy. Perhaps due to changes in maternal metabolism during the third semester, many women have reported that previously adequate doses became insufficient to relieve their drug cravings. Return of craving, of course, can lead to relapse to illicit opioid use and all the associated dangers to mother and fetus. Accordingly, the author recommends individualization of methadone doses, which should be titrated to minimize discomfort and possible opioid use by the mother.
Limitations of the study include the small number of subjects, lack of long-term follow-up and the fact that all these women received comprehensive care that may not be available in every center that cares for pregnant women on methadone.