Handling an issue that isn't black and white.
Use of social drugs by a minority of pregnant and breastfeeding mothers is a fact of life. Breastfeeding is the only way to feed an infant for that infant to be able to achieve optimum growth, health and mental development. Drug-using mothers need to know how their drug habit will impact on their baby and their lactation and how artificial formula will affect them and their baby. Informed decision-making, which achieves the best outcome for both baby and mother, is the goal.
Unfortunately these drugs are all drugs of addiction to varying degrees, so the ‘easy’ solution of “just give it up” isn’t as easy as we’d like it to be – and may not be an option at all for some mothers. It’s not a black and white issue – there’s no ‘one answer fits all’ solution.
There is a significant risk:benefit judgment call to be made in every case. To be able to assist a mother and her other health care advisers to make an appropriate decision many factors should be considered together.
Careful and caring counselling is required of the health professional who is assisting a mother to make decisions that will impact on the present and future health of her baby. An understanding of the many social factors that influence her, the very latest information about specific drug transfer into breastmilk and its effect on the infant AND the effect on her infant of not being breastfed in each circumstance all need to be balanced in your counselling.
It is also significant to determine what other drugs (prescription or otherwise) the mother may be taking, as these could cause interactions potentiating the effect of one or the other. The stage of the lactation, the age of the baby, the condition of the baby (particularly if preterm or ill) and the number of breastfeeds or amount of breastmilk the infant receives are all factors that will influence your discussions and recommendations.
There are few recent figures available that reflect the incidence of illicit drug use during lactation but it is generally thought to be low. Polysubstance abuse (nicotine, caffeine and alcohol; or a mixture of licit and illicit drugs) causes cumulative and sometimes enhanced risk factors for the infant. Most women who continue their drug use during pregnancy are unlikely to stop it during lactation.
However, don’t underestimate what mothers will do for the benefit of their children.
There are many reasons why a woman may be a smoker – some of these reasons are common with why a woman would choose to bottle feed her infant (or wean very early). Power relations, the construction of her social identity, social control and poverty are all closely related to why women smoke. Some of these factors are also involved with why a woman chooses to bottle feed – lack of body confidence, poverty and social identity.
Many countries survey their populations to determine the incidence of smoking. As an example 21.5% of women of child-bearing age in the USA are regular smokers with 17% continuing to smoke during pregnancy (National Health Interview Survey 2005); 21.3% in Canada with 13% reporting smoking during pregnancy (Canadian Tobacco Use Monitoring Survey 2005) and 21.6% of Australian women of child-bearing age, with 17.3% smoking during pregnancy (Australian Institute of Health & Welfare 2004 National Drug Strategy Household Survey).
Giglia et al (2006) reported that pregnancy is a time when many women are motivated to stop smoking. Unfortunately many return to their habit after the birth of the baby (Lawrence, 2005).
Artificially feeding the baby has been found to be more closely related to a woman resuming smoking again after the birth.
Nicotine has also been reported to be one of the most addictive drugs.
Transfer of nicotine to the infant:
Transfer into breastmilk:
Nicotine is rapidly and completely absorbed from the respiratory tract into the mother’s bloodstream.
The transfer into breastmilk is by simple diffusion and the maternal serum and breastmilk levels of nicotine are closely related.
Nicotine has a half-life of about 97 minutes.
Absorption by the infant:
The infant absorbs nicotine readily from the air, along with tar and carbon monoxide and another 2000 or so by-products of cigarette smoke – passive smoking. Nicotine is absorbed a little more slowly and less efficiently from breastmilk.
The levels in the baby’s bloodstream are greater from passive smoking than from ingesting nicotine only via breastmilk, but the effects are cumulative. Levels of urinary cotinine, a metabolite of nicotine and a specific marker for tobacco smoke exposure, is found in levels up to 10-times higher in breastfed infants of mothers who smoke compared to artificially-fed infants whose mothers smoke (Mascola, 1998).
Effect of cigarette smoking on lactation:
Women who smoke are less likely to intend to breastfeed, less likely to initiate breastfeeding, and more likely to breastfeed for a shorter duration than non-smokers. They may have a reduced volume of breastmilk which could be linked to lowered prolactin levels, though the effect persists even after lactogenesis comes under autocrine control. Amir et al (2003) found psychosocial factors rather than physiological factors to be largely responsible for the lower rates of breastfeeding found in women who smoke compared with those who do not.
Effect of cigarette smoking on the infant:
Nicotine flavours the milk and is a known appetite suppressant. Babies often show fussiness at the breast and sometimes breast refusal if the mother has just recently had a cigarette. Other symptoms, which can be attributed to nicotine ingestion, include vomiting, diarrhoea, restlessness and an increased heart rate. There is an increase in colic in infants of mothers who smoke 5 or more cigarettes per day.
Babies who are artificially fed in a household where smoking occurs are more frequently hospitalised and have a higher incidence of respiratory and gastro-intestinal illness. Colic is much more common in this group too. Infants exposed to passive smoke also have a higher incidence of middle ear infections and compromised lung function and development. However, probably the most significant effect of cigarette smoking in the household is the greatly increased risk of Sudden Infant Death Syndrome.
Breastfeeding will help to protect the infant against all of these health concerns.
Babies of mothers who smoke have an average birth-weight of 200g less than those whose mothers don’t smoke. Weight gain in the first few months is also reported to be less – though by 12 months no differences are evident. Gross motor development and mental development don’t appear to be affected by maternal smoking during lactation.
Counselling the breastfeeding mother who smokes
The American Association of Pediatrics (AAP) has not classified maternal smoking (Committee on Drugs 2001). They acknowledge that, while maternal smoking and the transfer of chemicals from smoking into breastmilk is deleterious, health outcomes attributable to maternal smoking are poorer for infants artificially-fed than those breastfed and therefore they encourage continued breastfeeding.
“Clearly, it is not ideal to smoke and breastfeed. But it is worse to smoke and not to breastfeed.” (Minchin, 1991, p187)
Quitting would be the ultimate recommendation but, short of that, discussion should focus around reducing the infant’s exposure to nicotine while ensuring the mother still appreciates the value of continuing to breastfeed her infant.
Strategies could include:
- educating the mother regarding use of nicotine transdermal patches instead of smoking
- reducing the number of cigarettes she smokes and perhaps changing to low nicotine brands
- smoke AFTER breastfeeding and use other settling techniques for the infant for the hour and a half it will take until nicotine has reached it’s first half-life
- don’t allow smoking in enclosed areas where the baby may be eg. inside the house or inside the car
- don’t take baby into smoky environments and don’t allow people to smoke around the baby
- cover hair with a scarf and clothing with a big old shirt while smoking – remove and leave outside after smoking. Wash hands and face after smoking.
- observe baby for nicotine-related symptoms and further reduce exposure if possible.
The nicotine patch
Ilett et al (2003) found that mothers who smoked on average 17 cigarettes per day had similar nicotine and cotinine levels in their breastmilk as they did when they used a 21mg per day nicotine transdermal patch. At reduced patch concentrations (14mg/day and 7mg/day) the nicotine and cotinine levels in breastmilk decreased significantly. The researchers concluded that undertaking maternal smoking cessation with the nicotine patch is a safer option than continued smoking.
Combined with the decreased exposure to environmental smoking by-products the difference to the infant would be significant.
A significant number of women between 14 and 39 years of age drink alcohol regularly (at least one standard drink per week) in many countries. A Norwegian study (Alvik 2006) reported that 80% of women breastfeeding a 6-month old used alcohol. They had, however, reduced by half the amount of alcohol they used to consume prior to pregnancy. Relatives, friends and health professionals for many years have recommended that breastfeeding mothers have a glass of alcohol to relax of an evening, purporting it to increase milk supply and perhaps even breastmilk quality. This is erroneous.
Transfer of alcohol to the infant:
Alcohol readily crosses into breastmilk by simple diffusion, achieving levels approximately equal to that in the maternal blood stream.
Alcohol flavours the breastmilk and changes the smell of breastmilk. (Mennella 1992)
Effect of alcohol on lactation:
Oxytocin release, necessary for the milk-ejection reflex to function is inhibited, or at least partially inhibited, after 2 standard drinks of alcohol. (Mennella, 2005)
Milk volume is reduced by about 23% after one standard drink of alcohol. (Mennella, 2005). Note that alcohol in any form (beer, stout, wine, etc) is NOT a galactagogue!
Caloric value of breastmilk is unchanged after ingestion of alcohol.
Effect of alcohol on the infant:
Due to liver immaturity, infants detoxify alcohol at about half the rate of adults until they are at least 3 months old. Alcohol exposure to a younger baby can be far more detrimental than to an older infant.
1 standard drink per day has been associated with a decrease in psychomotor development in some studies, but not all. Binge drinking (5 standard drinks) weekly has the same effect. 1 standard drink results in the infant suckling more but getting less milk and becoming mildly sedated. In the 4.5 hours following ingestion of alcohol in breastmilk, infants were found to be more wakeful. (Mennella 2001A)
Effect of alcohol on the mother
More than 2 standard drinks at a time can impair the mother’s judgement and functioning. Regular alcohol consumption is often associated with depression and fatigue. The diet of a woman who drinks regularly may be deficient in nutrients.
Counselling the mother who consumes alcohol
Discussion should include:
- minimising alcohol exposure to the infant for at least the first 3 months of life
- choosing low alcohol drinks
- eating before and while drinking
- avoiding breastfeeding for 2 to 3 hours after drinking
- storing alcohol-free breastmilk for use after moderate or heavy drinking
- alcohol will REDUCE milk intake by the baby. Ignore, or educate correctly, anyone who recommends its use.
Caffeine is one of the most popular drugs in the world. It is present in coffee, tea, cola-based drinks, some foods and medications. Many mothers use a cup of hot coffee to relax and aid milk ejection. Coffee varies considerably in the amount of caffeine present depending on the size of the cup and the method of preparation (eg Turkish ‘mud’ compared to soluble instant coffee).
Transfer of caffeine to the infant
Transfer into breastmilk varies from person to person depending on their ability to absorb and eliminate the drug. Generally, peak levels of caffeine are found in breastmilk 60 minutes after ingestion.
Less than 1% of the maternal dose is transferred to the infant. A maternal dose of one or two cups of coffee (60 – 180 mg caffeine) is clinically insignificant for the infant. Newborn babies may take up to 80 hours to metabolise caffeine. Because of this long excretion time in the very young baby, caffeine may accumulate in significant amounts. By 6 months of age they are able to metabolise caffeine in 2.6 hours. (Aldridge 1979, Hale 2006)
Effect of caffeine on milk composition:
3 cups of coffee or more per day may be associated with a reduction in iron content of breastmilk of up to one third of that of women who don’t consume coffee. Moreira (2005) noted the iron-reducing activity of coffee beverages was not influenced by caffeine, but rather by the presence of chlorogenic acids in coffee.
Chronic coffee consumption by the mother could result in iron deficiency anaemia in the breastfed infant. (Liston, 1998)
Effect of caffeine on infant:
Maternal consumption of more than 300mg caffeine (about 3 cups brewed or filtered coffee) per day has been associated with jitteriness and irritability in the baby and also poor sleeping patterns. Maternal cigarette smoking accentuates the effects of caffeine in the breastfed infant.
Counselling the mother who consumes caffeine:
Advising the mother of the effects of caffeine on her infant will give her the opportunity to consider reducing her caffeine intake by choosing decaffeinated alternatives. Occasional caffeinated beverages and foods have minimal clinical effect on the infant.
7.6% of American women (SAMHSA, 2006) , 10.2% of Canadian women and 11% of Australian women of childbearing age used marijuana in the year prior to the survey. Usage during pregnancy in America is between 3 and 16% of women. In comparison with alcohol and nicotine usage, marijuana is the drug least likely to be reduced during pregnancy. Delta-9-tetrahydrocannabinol (THC) is metabolized in the liver and has a half-life of 25 to 57 hours (Hale 2006). In chronic users, its half-life could be as long as 4 days because it is stored in body fat; it can be detected for up to a month after last use..
Transfer of marijuana to the infant
The active component (THC) is fat-soluble and transfers in moderate amounts into breastmilk; higher levels are found in breastmilk than in maternal serum with chronic heavy use (Perez-Reyes, 1982).
via passive smoking:
As with nicotine the baby will absorb significant amounts of the drug if he is in an environment where smoking of marijuana is occurring.
Effect of marijuana on lactation
Some animal studies have found marijuana reduces basal prolactin levels therefore reducing milk supply.
Effect of marijuana on the infant
This remains quite controversial. Animal studies have shown that structural changes occur in the brains of newborn animals exposed to marijuana through their mother’s milk. In the human baby the first 12 months to 2 years is a time of rapid growth and development of the brain and central nervous system – and insult at this time could have far-reaching effects. Few studies have demonstrated long-term effects on the breastfed infant, though Astley (1990) reported marijuana exposure via the mother's milk during the first month postpartum appeared to be associated with a decrease in infant motor development at one year of age Short-term effects appear to be confined to sedation, weakness and poor feeding patterns.
Effect of marijuana on the mother
Marijuana causes reality distortion and maternal judgement may be impaired. Secondary behavioural changes may interfere with a mother’s ability to care for her infant or to breastfeed adequately. After the marijuana ‘high’ the mother may sleep very deeply and be unresponsive to her baby’s needs.
Counselling the mother who uses marijuana
The AAP (2001) has listed marijuana in Table 2: “Drugs for Which the Effect on Nursing Infants Is Unknown but May Be of Concern”, listing only one report of adverse events.
Advice similar to that given regarding cigarette smoking will reduce the exposure of the infant to passive smoke inhalation. For a mother who only occasionally uses marijuana she could prepare to have un-affected milk available for her infant and would be advised to have a carer who is not drug-affected to assist her with the infant during this time.
This is a difficult situation to counsel in as there is so little evidence of long-term detrimental effects of marijuana use on the infant, but there is considerable evidence of long-term detrimental effects of artificial baby milks on infants.
If you do advise artificial feeding, can adequate hygiene be maintained? Is the mother sufficiently responsible to mix the artificial baby milk in the appropriate strength? When she’s ‘stoned’ can she be trusted to prepare artificial baby milk and feed her baby? Can she afford to buy artificial baby milk, or will she swap to unsuitable substitutes too early? Being fed a breastmilk substitute, her infant will suffer more ill health – will she seek adequate and timely treatment?
Are any, or all, of these factors more detrimental to the infant than continuing to be breastfed nutritionally superior milk, which has doubtful contamination?
Methamphetamine use is growing problem. In Australia it is the second most commonly used illicit drug after cannabis, with 9% of Australians having ever tried it. In America it is the most common drug-related law enforcement problem faced. Crimes of burglary, domestic violence, child abuse and sexual violence have increased as a direct result of methamphetamine use. Methamphetamine usage is closely associated with mental disorders such as psychosis. If the drug is injected the risk of HIV AIDS and hepatitis C is increased. Dexamphetamine is commonly used therapeutically to treat Attention Deficit Disorder. In therapeutic usage no untoward effects have been reported in breastfed infants.
Transfer of methamphetamine to the infant:
Significant transfer of drug into breastmilk. 18 – 68 mg/kg/day transferred in two studies (Ilett 2002) Breastfeeding is contraindicated while breastmilk is affected. Pumping and discarding the breastmilk is recommended for 24 hours after the last dose.
Effect of methamphetamine on infant:
None reported via breastmilk. (Ilett 2002, Hale 2002)
Effect of methamphetamine on mother:
The mother is likely to suffer from hallucinations, agitation, seizures, acute paranoid psychosis, extreme hypertension, hyperthermia, tachyarrhythmias - dependent on the dose taken. While under the influence of this drug she will be incapable of providing any care for her infant.
Counselling the mother who uses methamphetamine:
This drug causes major personal and society harm. Support to attend a drug rehabilitation service should be provided. Due to the very high risk of child neglect and abuse ongoing surveillance of the child’s situation is required.
Alternative arrangements should be made to care for children while the mother is affected by this drug. Breastfeeding should be withheld for 24 hours after the last dose of methamphetamine.
Approximately 1% of women of child-bearing age used heroin in the 12 months prior to be surveyed. Of this number, 87% are probably infrequent users ie. may have only used it once in that 12 months. Heroin is seen as a highly addictive drug; however the usage surveys don’t support this for most people who have used it. Regular users of heroin tend to be unemployed, though, surprisingly are more likely to have trade or tertiary qualifications. Lifestyle issues are very important to consider when counselling this woman.
Transfer of heroin to the infant:
Heroin passes into breastmilk. It has a poor oral bioavailability from the milk – ie it is not absorbed well by the infant
Effect of heroin on the infant:
If the mother has been a regular user during pregnancy her baby will be growth retarded. The infant will experience withdrawal symptoms dependent on the mother’s dosage and length of addiction. Sedation, respiratory depression, vomiting and irritability can occur from exposure via the breastmilk.
Effect of heroin on the mother:
She will be incapable of caring appropriately for her baby while affected with this drug. Counselling the mother who uses heroin If the mother is an occasional user she may be able to have her baby cared for by a responsible adult at those times. If she is a regular user, breastfeeding is contraindicated and her ability to care for her child at all is probably doubtful. Support for her to be referred to a drug rehabilitation service is essential. With occasional use and continuing to breastfeed the mother should be made aware of the risk of contracting hepatitis B, C or HIV. When the mother is in an acute stage of HIV, such as when she first acquires the disease, it can be readily passed on to her infant via breastmilk. This may also be a concern if her sexual partner is a substance abuser, putting her at risk.
Methadone is a long-acting opiate used in detoxification and treatment of opiate addicts (primarily heroin). This drug is approved by the AAP (2001) for use by women breastfeeding their infants.
Transfer of methadone to the infant:
Methadone peaks in the maternal serum ½ to 1 hour after oral ingestion and has a very long half-life (13-55 hours) (Hale 2002). The dose transferred via breastmilk is largely dose-dependent, but generally averages about 2.8% of the maternal dose. Many studies have found the levels in breastmilk to be so low as to not have a deleterious effect on the infant.
Effect of methadone on the infant:
Methadone exposure via the breastmilk assists the baby to withdraw from the drug following intra-uterine exposure. Many breastfed babies will require no treatment, whereas artificially fed infants will. (Abel-Lativ 2006) Observe the infant for sedation, respiratory depression and neonatal abstinence syndrome.
Counselling the mother on a methadone program:
Mothers should be encouraged to continue to breastfeed their infants – it’s preferable that the infant withdraws slowly from the drug and breastfeeding is the best way to do this. To begin to limit exposure to the drug the mother could take her daily dosage just prior to the longest sleep the baby usually has. Gradual withdrawal will occur as complementary foods are commenced and the baby breastfeeds less frequently,
Babies born to mothers who abuse drugs start life with a handicap. Their compromised intra-uterine life has affected their nutritional status, their growth and in some cases their intellectual ability. After birth they go through withdrawal symptoms that affect their health and adaptation to extra-uterine life.
Artificial baby milk provides second grade nutrition, no protection against infections, has the potential to cause chronic disease and further inhibits the intellectual potential of the infant.
Breastmilk is medicine for these babies and breastfeeding is about more than merely providing nutrition. Breastfeeding develops a bond between mother and baby, which may empower and motivate positive change on the part of drug-abusing parents, while decreasing the risk of future child maltreatment. This should be considered along with concerns about the likelihood or degree of drug exposure the baby has if breastfed. If the child protection authority supervising the case considers it safe for the parents to retain care of their infant, education on safe breastfeeding practices should be included as a part of the rehabilitation plan.
No effort should be spared in assisting the mother to receive treatment for her addiction for her own and her baby’s future. Giving birth and then breastfeeding can be an empowering and life changing experience for a woman and may be the catalyst that causes her to stop her substance abuse. Before counselling a woman to feed artificial baby milk, consider giving her the opportunity to meet this challenge.
Denise Fisher, MMP, BN, RN, RM, IBCLC Sandpiper Education PO Box 2405 Chermside Centre 4032 Queensland. Presented at Breastfeeding: Nurturing and Knowledge NMAA 25thAnnual Tasmanian Branch Seminar, Devonport, August 2000. Revised: November 2006.
- Abdel-Latif ME, Pinner J, Clews S, Cooke F, Lui K, Oei J. (2006) Effects of breast milk on the severity and outcome of neonatal abstinence syndrome among infants of drug-dependent mothers. Pediatrics. 117(6):e1163-9.
- Aldridge A, Aranda JV, Neims AH. 1979 Caffeine metabolism in the newborn. Clin Pharmacol Ther. 25(4):447-53.
- Alvik A, Haldorsen T, Lindemann R. (2006) Alcohol consumption, smoking and breastfeeding in the first 6 months after delivery. Acta Paediatr. 95(6):686-93.
- American Academy of Pediatrics, Committee on Drugs. (2001) The transfer of drugs and other chemicals into breastmilk. Pediatrics. 108(3):776-789
- Amir LH, Donath SM. (2003) Does maternal smoking have a negative physiological effect on breastfeeding? The epidemiological evidence. Breastfeed Rev.;11(2):19-29.
- Astley S, Little RE. Maternal marijuana use during lactation and infant development at one year. Neurotoxicol Teratol. 1990;12:161–168.
- Australian Institute of Health and Welfare. National Drug Strategy Household Survey 2004. [Online].
- Available: http://www.aihw.gov.au/publications/index.cfm/title/10122
- Astley S, Little R 1990. Maternal marijuana use during lactation and infant development at one year. Neurotoxicol teratol 2(12) 161-168
- Cobo E, 1973. Effect of different doses of ethanol on the milk-ejecting reflex in lactation women. Am J Obst Gynecol 115 817-821.
- Dahlstrom A, Ebersjo C, Lundell B. (2004) Nicotine Exposure in Breastfed Infants. Acta Paediatr; 93(6):810-6.
- Giglia RD, Binns C, Alfonso H. (2006) Which women stop smoking during pregnancy and the effect on breastfeeding duration. BMC Public Health, 6:195 doi:10.1186/1471-2458-6-195. http://www.biomedcentral.com/1471-2458/6/195 Accessed Sept 2006.
- Hale T 2002. Medications and Mothers’ Milk 10th ed, Pharmasoft Medical Publishing, Texas
- Howard C, Lawrence R 1998. Breast-feeding and drug exposure. Obs Gynec Clin of Nth Am 25(1) 195-217.
- Ilett K. (2002) Drugs and Breastfeeding in the Perinatal Period. Presentation made at ALCA Conference, Sydney Australia. Available online at http://www.pharm.uwa.edu.au/drugs-milk/ALCA- 2002/frame.html Accessed November 2006.
- Ilett K, Hale T, Page-Sharp M, Kristensen J, Kohan R, Hackett L. (2003) Use of nicotine patches in breast-feeding mothers: transfer of nicotine and cotinine into human milk. Clin Pharmacol Ther.; 74(6):516-24.
- Liston J 1998. Breastfeeding and the use of recreational drugs – alcoholism, caffeine, nicotine and marijuana. Br Review 6(2) 27-30.
- Little RE, Northstone K, Golding J; ALSPAC Study Team. (2002) Alcohol, breastfeeding, and development at 18 months. Pediatrics. 2002 May;109(5):E72-2.
- Little RE 1989. Maternal alcohol use during breastfeeding and infant mental and motor development at one year. New Engl J Med 321 425-430
- MacMahon, J 1997. Perinatal Substance Abuse: The impact of reporting infants to child protective services. Pediatrics 100(5) e1. Available: http://www.pediatrics.org/
- Makkai T, McAllister I 1998. Patterns of drug use in Australia 1985 – 1995. National Drug Strategy [Online] Available: http://www.health.gov.au/pubhlth/publicat/patterns.pdf
- Mascola MA, Van Vunakis H, Tager IB, Speizer FE, Hanrahan JP. 1998 Exposure of young infants to environmental tobacco smoke: breast-feeding among smoking mothers. Am J Public Health. 88(6):893-6.
- Maza P, et al 1998. Maternal Lifestyles Study. Caretaking environment and stability of substance- exposed infants at one month corrected age. An NY Acad Sc 846, 358-361.
- Mennella JA, Pepino MY, Teff KL. 2005 Acute alcohol consumption disrupts the hormonal milieu of lactating women. J Clin Endocrinol Metab. 90(4):1979-85.
- Mennella J. 2001 Alcohol's effect on lactation. Alcohol Res Health. 25(3):230-4.
- Mennella JA, Garcia-Gomez PL. (2001A) Sleep disturbances after acute exposure to alcohol in mothers' milk. Alcohol. 25(3):153-8.
- Mennella J 1998. Short-term effects of maternal alcohol consumption on lactational performance. Alcohol Clin Exp Res, 22(7) 1389-1392.
- Mennella J, Beauchamp G 1992. The transfer of alcohol to human milk. Br Review 2(6) 286-290.
- Minchin M 1991. Smoking and breastfeeding: An overview. J Hum Lact 7(4) 183-188.
- Moreira DP, Monteiro MC, Ribeiro-Alves M, Donangelo CM, Trugo LC. 2005 Contribution of chlorogenic acids to the iron-reducing activity of coffee beverages. J Agric Food Chem. 53(5):1399-402.
- Perez-Reyes M, Wall ME. 1982. Presence of delta-9-tetrahydrocannabinol in human milk. N Engl J Med. 307:819–820.
- Schulte P 1995. Minimising alcohol exposure of the breastfed infant. J Hum Lact 4(11) 317-319.
- Wakefield M, Jones W. (1998) Effects of smoking cessation program for pregnant women and their partners attending a public hospital antenatal clinic. Aust NZ J Public Health 22(3 suppl):313-20
- Wiemann C, DuBois J, Berenson A, 1998. Racial/Ethnic differences in the decision to breastfeed among adolescent mothers. Pediatrics 101(6) e11. Available: http://www.pediatrics.org/