Improving Treatment for Drug-Exposed Infants
Treatment Improvement Protocol (TIP) Series 5

Effects of In Utero Heroin Exposure

The effects of heroin on the neonate are as follows:

1. Low Birth Weight - The low birth weight is due primarily to symmetric intrauterine growth retardation. Low birth weight may also be due to prematurity. In either case, low birth weight results in the slowing of both body and head growth. (See definitions of medical terms in Appendix F.)
2. Meconium Aspiration - Meconium aspiration may be caused by hypoxia in association with antepartum or intrapartum passage of meconium secondary to fetal stress.
3. Neonatal Abstinence Syndrome (Withdrawal) - Neonatal abstinence syndrome occurs in about 60 to 80 percent of heroin-exposed infants. Its onset is usually within 72 hours of birth, with possible mortality if the syndrome is severe and untreated. The syndrome involves several body systems. Central nervous system (CNS) signs of abstinence include irritability, hypertonia, hyperreflexia, abnormal suck, and poor feeding. Skin abrasions may result from general hyperactivity. Seizures are seen in 1 to 3 percent of heroin-exposed infants. Gastrointestinal signs include diarrhea and vomiting. Respiratory signs include tachypnea, hyperpnea, and respiratory alkalosis. Autonomic signs include sneezing, yawning, lacrimation, sweating, and hyperpyrexia. If the infant is hypermetabolic, the postnatal weight loss may be excessive and subsequent weight gain suboptimal unless higher caloric intake is provided. In cases demonstrating signs suggestive of the abstinence syndrome, other diagnoses should also receive the clinician's full attention. For example, sepsis, metabolic disorders, and CNS hemorrhage or ischemia should be considered in making the differential diagnosis. Premature infants seem to manifest fewer overt symptoms of opiate abstinence syndrome. These differences may be due to the developmental immaturity of the preterm CNS, which might ameliorate the clinical appearance of abstinence symptoms, or to variations in total drug exposure due to a shortened gestation (Doberczak, Kandall, and Willets, 1991).
4. Delayed Effects - Delayed effects include subacute withdrawal with symptoms such as restlessness, agitation, irritability, and poor socialization that may persist for 4 to 6 months.
5. Sudden Infant Death Syndrome (SIDS) - Epidemiologic studies suggest an association between SIDS and interuterine exposure to opiates (including methadone), but somewhat weaker links between SIDS and cocaine exposure (Kandall and Gaines, 1991).
6. Effects of mother's behavior - Adverse effects may be due to the life circumstances and behavior of the mother who uses heroin. Lack of prenatal care, poor nutrition, medical problems and the abuse of other drugs pose significant risk to the mother and the fetus. In addition, heroin use can cause sexual disinhibition, which increases the possibility of the mother's engaging in behaviors that place her at high risk for contracting HIV, such as sharing needles. Or the addicted mother may engage in sex for drugs with partners infected with HIV and other sexually transmitted diseases (STDs).

Effects of In Utero Methadone Exposure

Maternal methadone maintenance is a valuable treatment modality when administered under medical supervision. Although methadone poses some threat to the fetus, it is important to contrast the benefits of methadone in pregnancy with the risks associated with the continuing use of heroin. For this reason, methadone maintenance is often recommended for pregnant opioid-dependent women.

Benefits of Methadone Maintenance During Pregnancy

1. Assists women in staying heroin free - The purpose of methadone is to provide an opioid-dependent individual with a legal alternative to an illicit substance, the effects of which can be monitored by a medical professional as the individual goes through withdrawal and after withdrawal. Methadone maintenance reinforces the woman's desire to abstain from using heroin. Off heroin, the woman is in a better position to manage her life so as to maximize the possibilities for a healthy lifestyle for herself and her baby.
2. Leads to more consistent prenatal care - Studies have shown that methadone maintenance leads to more consistent prenatal care, giving medical providers and others involved the opportunity to better manage the pregnancy and the various aspects of the pregnant woman's care.
3. Lessens possibility of fetal death - Maternal opiate withdrawal can cause fetal death (Hoegerman and Schnoll, 1991). Significant opiate use is associated with increased pregnancy loss. The incidence of pregnancy loss is definitely decreased if the woman is maintained on methadone.
4. Lessens decreased fetal growth and improves growth of newborn - Significant opiate use is associated with decreased fetal growth and affects the growth of the newborn. Once the baby is born, the baby will often develop more normally if the mother has been maintained on methadone.
5. Reduces risk of HIV infection - Methadone maintenance reduces the transmission of HIV (Blix et al., 1988; Cooper, 1989). Women maintained on methadone do not spread the growth of the HIV virus as do women who use morphine, cocaine, and heroin (ADAMHA News [2], 1992). The reason for the reduced HIV rate is that the use of methadone decreases the practice of high-risk behaviors (unsafe sex and the sharing of used intravenous needles that may contain HIV-infected blood products).
6. Enables the woman to breastfeed her infant - Breastfeeding is not contraindicated if the woman is methadone maintained. Thus, if they are HIV-negative and free of other drug use, women on methadone can be encouraged to breastfeed their babies. Given the well-established importance of breastfeeding in the mother-infant bonding process, the fact that methadone-maintained women can often breastfeed their infants is of vital significance. This advantage to methadone should be emphasized by providers when assisting women in the decisionmaking process regarding whether to begin methadone maintenance.

Risks of In Utero Methadone Exposure

Despite the significant advantages of methadone to an opioid-dependent pregnant woman, dangers to the fetus and to the newborn still exist, as described below.

1. Low Birth Weight - In utero exposure to methadone may lead to low birth weight caused by symmetric fetal growth retardation involving fetal weight, length, and head circumference. There is a lack of consensus on the appropriate methadone dosage schedule during pregnancy. Some studies indicate that a higher dose in the first trimester leads to a more optimal birth weight. Thus, a higher dosing schedule during this period may be considered (Kandall et al., 1976).
2. Neonatal Methadone Abstinence Syndrome - Although the neonatal methadone abstinence syndrome is similar to that of heroin, it is typically more severe. Whether severity is related to maternal dosage is controversial (Harper et al., 1977). Late withdrawal can occur at 2 to 3 weeks of age, and subacute withdrawal can persist until 6 months of age. These phenomena may be related to variations in the metabolism of methadone due to placental transfer or neonatal metabolism. Methadone is also known to accumulate in CNS tissue (Finnegan and Kaltenbach, 1992.)
3. Seizures - Seizures attributed to withdrawal will be seen in some drug-exposed infants. For example, in one study of 301 neonates passively addicted to narcotics, 18 had seizures attributed to withdrawal (Herzlinger et al., 1977). Some studies have shown that infants exposed to methadone may have an increased incidence of seizures (Herzlinger et al., 1977; Harper et al., 1974). Others in the field believe that it is actually the use of diazepam and phenobarbital that increases the incidence of seizures in methadone-exposed babies. The latter recommend the use of paregoric.
4. Thrombocytosis - At 4 to 10 weeks, methadone-exposed neonates are at risk to develop thrombocytosis, which may persist for 6 to 10 months (Burstein et al., 1979).
5. Hyperthyroid State - Elevation of T3 and T4 during the first week of life has been documented (Jhaveri et al., 1980).
6. SIDS - When controlled for other high-risk variables, the rate of SIDS among opiate-exposed infants is about 3-4 times higher than in the general population. The increased rate of SIDS is less impressive for cocaine-exposed infants (Kandall and Gaines, 1991; Kandall et al., 1993).