Direct and indirect effects of breast milk on the neurobehavioral and cognitive development of premature infants

Eighty-six premature infants were tested to examine the effects of maternal breast milk on infant development. Infants were classified by breast-milk consumption during the hospitalization period (M = 57.4 days) into three groups: those receiving minimal (<25% of nutrition), intermediate (25-75%), and substantial (>75%) amounts of breast milk. Infants in the three groups were matched for birth weight, gestational age (GA), medical risk, and family demographics. At 37 weeks GA, mother-infant interaction was videotaped, maternal depression self-reported, and neurobehavioral maturation assessed by the Neonatal Behavior Assessment Seale (Brazelton, 1973). At 6 months corrected age, infants were tested with the Bayley II (Bayley, 1993). Infants receiving substantial amounts of breast milk showed better neurobehavioral profiles-in particular, motor maturity and range of state. These infants also were more alert during social interactions, and their mothers provided more affectionate touch. Higher maternal depression scores were associated with lower quantities of breast milk, longer latencies to the first breast-milk feeding, reduced maternal affectionate touch, and lower infant cognitive skills. Maternal affectionate touch moderated the relations between breast milk and cognitive development, with infants receiving a substantial amount of breast milk and frequent touch scoring the highest. In addition to its nutritional value, breast milk may be related to improved maternal mood and interactive behaviors, thereby indirectly contributing to development in premature infants.     

The effect of supplementation with fish oil during pregnancy on breast milk immunoglobulin A, soluble CD14, cytokine levels and fatty acid composition

BACKGROUND: Breast milk contains many immunomodulatory factors (soluble CD14 (sCD14), IgA and cytokines) with the potential to influence infant immune development. OBJECTIVE: To determine if changes in breast milk omega-3 polyunsaturated fatty acid (n-3 PUFA) composition as a result of maternal dietary fish oil supplementation during pregnancy can modify levels of these immunological parameters in breast milk. METHOD: In a randomized controlled trial, 83 atopic women received either 4 g fish oil capsules (containing 3.7 g n-3 PUFA) (n = 40) or 4 g olive oil capsules (n = 43) from 20 weeks gestation until delivery. Breast milk was collected 3 days post-partum and fatty acids were analysed by gas liquid chromatography and IgA, sCD14 and cytokines (IL-5, IL-6, IL-10, TNF-alpha and IFN-gamma) were quantitated by ELISA or time resolved fluorescence (TRF). RESULTS: Omega-3 docosahexaenoic acid (DHA; 22:6n-3) and eicosapentaenoic acid (EPA; 20:5n-3) levels were significantly higher (P < 0.001) in breast milk from women supplemented with fish oil (n = 33, DHA mean 1.15%, SD 0.47% and EPA mean 0.16%, SD 0.07%) than in samples from the control group (n = 40, DHA mean 0.50%, SD 0.17% and EPA mean 0.05%, SD 0.02%). Breast milk arachidonic acid (AA; 20:4n-6) levels were significantly lower (P = 0.045) in the fish oil group (mean 0.55%, SD 0.12%) compared with the control group (mean 0.61%, SD 0.14%). Breast milk IgA was positively correlated with DHA (P = 0.046) and 22:5n-3 (P = 0.003), but inversely correlated with linoleic acid (LA; 18:2n-6) (P=0.034). Levels of sCD14 were also positively correlated with 22:5n-3 (P=0.009). Cytokines involved in IgA synthesis (IL-10 and IL-6) were also significantly correlated with both IgA and n-3 PUFA levels, although there were no differences in the levels of breast milk IgA, sCD14 or cytokines between study groups. CONCLUSION: Supplementation with fish oil during pregnancy significantly alters early post-partum breast milk fatty acid composition. omega-3 PUFA levels were positively associated with IgA and sCD14 levels, suggesting a relationship between fatty acid status and mucosal immune function.     

The vitamin D content of fortified milk and infant formula.

BACKGROUND. The fortification of milk and infant formula with vitamin D has had an important role in eliminating rickets in children and osteomalacia in adults. A recent outbreak of vitamin D intoxication caused by drinking milk fortified with excess vitamin D has led to questions about the level of vitamin D in milk from other producers. METHODS. We used high-performance liquid chromatography to measure vitamin D in samples of 13 brands of milk with various fat contents and 5 brands of infant formula purchased at random from local supermarkets in five Eastern states. RESULTS. Only 12 (29 percent) of the 42 samples of the 13 brands of milk and none of the 10 samples of the 5 brands of infant formula contained 80 to 120 percent of the amount of vitamin D stated on the label. Twenty-six of the 42 milk samples (62 percent) contained less than 80 percent of the amount claimed on the label. No vitamin D was detected in 3 of the 14 samples of skim milk tested (lower limit of assay, 4.7 IU per quart [5.0 IU per liter]). One milk sample labeled as containing vitamin D2 (ergocalciferol) contained vitamin D3 (cholecalciferol). Seven of the 10 samples of infant formula contained more than 200 percent of the amount stated on the label; the sample with the highest concentration contained 419 percent of the stated amount. None of the samples of infant formula contained less than the amount stated. CONCLUSIONS. Milk and infant-formula preparations rarely contain the amount of vitamin D stated on the label and may be either underfortified or overfortified. Since both underfortification and overfortification are hazardous, better monitoring of the fortification process is needed.     

A survey of Aflatoxin M1 in some commercial milk samples and infant formula milk samples in Goa,India

A survey of aflatoxin M1 (AFM1) contamination in packaged milk and infant formula milk samples in the Goan market, India, was conducted using high performance liquid chromatography, association of analytical communities approved commercial kit and a sensitive chemiluminescent sandwich enzyme-linked immunosorbent assay (ELISA). A total of 72 samples of infant formula milk food (18) and packaged milk samples (54) was analysed. One hundred per cent of the analysed samples exceeded the European Communities recommended limits (50 ng/L) and 75% of the samples exceeded Codex Alimentarius, Food Safety and Standards Authority of India (FSSAI) and US Food and Drug Administration recommended limits (500 ng/L). The range of contamination of AFM1 was found lower in infant milk formula (501–713 ng/L) than liquid milk (511–809 ng/L). The methods were also compared for their performance, and ELISA was found to be most suitable for analysis of low-level AFM1 contamination in milk.     

Neurobehavioral morbidity associated with disordered breathing during sleep in children: a comprehensive review

STUDY OBJECTIVES: To comprehensively review research on the association between childhood sleep-disordered breathing (SDB) and neurobehavioral functioning. DESIGN: Qualitative and quantitative literature review. SETTING: N/A. PATIENTS OR PARTICIPANTS: N/A. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: The findings of 61 studies of the relationship between childhood SDB and neurobehavioral functioning were critically evaluated and synthesized. There is strong evidence that childhood SDB is associated with deficits in behavior and emotion regulation, scholastic performance, sustained attention, selective attention, and alertness. There is also evidence that SDB has minimal association with a child's typical mood, expressive language skills, visual perception, and working memory. Findings have been insufficient to draw conclusions about intelligence, memory, and some aspects of executive functioning. Mechanisms by which SDB might result in neurobehavioral morbidity are being explored, but clinical symptoms such as chronic snoring remain the best predictors of morbidity. Short-term SDB treatment outcome studies are encouraging, but the long-term outcomes are not known. Failing to treat SDB appears to leave children at risk for long-term neurobehavioral deficits. CONCLUSIONS: Childhood SDB is associated with neurobehavioral morbidity. Applying commonly used guidelines for causal inference, even in the absence of a much-needed randomized clinical trial, there is strong evidence of association, consistent findings, and specificity of effect. There is suggestive evidence that this association fits the expected temporal pattern and that SDB is a biologically plausible cause of neurobehavioral deficits. Clinicians should be alert to the coexistence of SDB symptoms and concerns about a child's academic progress, attention, arousal, or behavior or emotion regulation.     

Exposure of the fetus and infant to hens'' egg ovalbumin via the placenta and breast milk in relation to maternal intake of dietary egg

BACKGROUND: Maternally derived allergens may be transferred to the developing infant during pregnancy and lactation. However, it is not known how manipulation of environmental allergen levels might impact on this early-life exposure. OBJECTIVE: To measure dietary egg allergen (ovalbumin (OVA)) in gestation-associated environments, in relation to maternal dietary egg intake. METHOD: OVA was measured by allergen-specific ELISA in maternal blood collected throughout pregnancy, infant blood at birth (umbilical cord) and in breast milk at 3 months post-partum. Samples derived from pregnant women undergoing diagnostic amniocentesis at 16-18 weeks gestation who were not subject to any dietary intervention, and from pregnant women, with personal or partner atopy, randomized to complete dietary egg exclusion or an unmodified healthy diet before 20 weeks gestation as a primary allergy prevention strategy. Maternal dietary egg intake was monitored closely throughout the study period by diary record and serial measurement of OVA-specific immunoglobulin G concentration. RESULTS: Circulating OVA was detected throughout pregnancy in 20% of women and correlated with both presence (P<0.001) and concentration (r=0.754, P<0.001) of infant OVA at birth (umbilical cord). At 3 months post-partum OVA was detected in breast milk samples of 35% women, in higher concentrations than measured in blood. Blood and breast milk OVA were not related to maternal dietary intake or atopic pre-disposition. CONCLUSIONS: Rigorous dietary egg exclusion does not eliminate trans-placental and breast milk egg allergen passage. This early-life exposure could modulate developing immune responses.     

Serum IgE in healthy infants fed breast milk or cow's milk-based formulas

A group of ninety-five infants was followed from birth to one year of age, and the total serum IgE concentration was studied. The infants were fed on breast milk, home-prepared cow's milk formula, or proprietary infant milk formula. Solid foods were introduced at 3.5 months of age. The breast milk group had lower IgE than the cow's milk group up to 4 months of age, i.e. until the end of exclusive milk feeding. The formula group had intermediate IgE values. The difference was not due to the presence of IgE antibodies to cow's milk in the bottle-fed infants, since no such antibodies could be detected. After the introduction of solid foods the differences between the groups disappeared. Our data suggest that exclusive breast milk feeding can reduce total serum IgE concentration in early infancy. Reference values for unselected infants and for infants with no atopic manifestations are reported.     

Microbiological monitoring of milk samples and surface samples in a hospital infant formula room

OBJECTIVE: Analyze the microbiological quality of reconstituted milk formulas and the surface hygiene in a hospital infant formula room, in the context of a worldwide emergence of Enterobacter sakazakii infections. MATERIAL AND METHODS: Over 3.5 years, monthly samples of reconstituted milk formulas as well as quarterly infant formula room surface samples were taken for bacteriological analysis. RESULTS: Of the 156 formulas analyzed, 54 carried microorganisms but no pathogenic bacteria. The presence of Bacillus species was found in 54% of the formulas for premature infants and in 19% of the other formulas (significant difference). Bacteria, probably brought by operators during reconstitution of the powdered formulas, were found in four of 156 samples (two negative-coagulase staphylococcus, one alpha-hemolytic streptococcus, and one Clostridium bifermentans). Surfaces were studied using 117 samples divided into 11 series: 4.3% of the points carried pathogenic bacteria (Enterobacter cloacae, Pseudomonas fluorescens, Bulhkholderia cepacia, Staphylococcus aureus). DISCUSSION: The presence of Bacillus species should be analyzed thoroughly so as to differentiate Bacillus cereus from other nonpathogenic species. The microbiological analysis techniques used for reconstituted infant formulas can be simplified. CONCLUSION: The quality of the infant formulas seems satisfactory. Hygiene practices provide good microbiological quality in reconstituted infant milk formulas. Microbiological monitoring of these preparations and the infant formula room surfaces is an important aspect of the quality assurance policy, which makes it possible to take corrective measures when an unsatisfactory result is found.     

The interaction of infant formula with macrophages: effect on phagocytic activity, relationship to expression of class II MHC antigen and survival of orally administered macrophages in the neonatal gut

The effect of infant formula on human peritoneal and breast milk macrophages has been investigated. The ability of peritoneal macrophages to subsequently ingest and degrade immune complexes was slightly impaired, but breast milk cells were not affected. However, the cells were found to have bound antigenically intact casein and beta-lactoglobulin, although little, if any, alpha-lactalbumin was bound. Furthermore, a positive correlation was found between binding of these proteins and expression of HLA-DR antigen. Labelled macrophages fed to newborn mice survived for at least 4 hr in the gastrointestinal tract and, in some cases, localized in the mucosal tissue. In one case a labelled cell was found in the spleen. These findings indicate that breast milk macrophages may be able to perform immunological functions in the gut, and suggest that binding of cows' milk proteins by macrophages may constitute a first step in the sensitization of the neonate to cow's milk proteins. Human milk macrophages may also play a protective role by acting as antigen-presenting cells in the local immune response of the gut.     

Effects of lipolysis or heat treatment on HIV-1 provirus in breast milk

BACKGROUND: Transmission of HIV-1 infection through breastfeeding is associated with integrated DNA (provirus) in milk cells. Reduction of HIV-1 DNA in milk may lessen infectivity. PURPOSE: To investigate efficacy of two methods available in developing countries to reduce HIV-1 proviral DNA in breast milk. METHODS: Methods simulated field conditions; milk was heated by bringing it to a boil, for instance, over a cooking fire, and lipolysis was done at room temperature. Four HIV-positive pregnant women were recruited for this pilot study, instructed to feed formula exclusively, and to stimulate milk production using pumping. Milk was collected twice weekly for 3 weeks and analyzed qualitatively for HIV-1 proviral DNA by polymerase chain reaction at three stages: 1) fresh, 2) after standing for 6 hours, and 3) after having been brought to the boiling point. RESULTS: Seventeen samples from 4 mothers were analyzed. Fifteen of 17 fresh samples (88%) had measurable HIV-1 proviral DNA despite all mothers' having had low or undetectable plasma viral loads. Lipolysis (standing at room temperature) for 6 hours did not destroy proviral DNA: 6 of 7 samples (86%) tested positive for DNA after lipolysis. No samples of milk (n = 8) brought to a boil were positive for HIV-1 proviral DNA (p <.0001). CONCLUSIONS: This preliminary evidence suggests that inherent lipolytic activity of fresh breast milk is inadequate for destruction of HIV-1; bringing breast milk to a boil may result in decreased HIV-1 infectivity; and breast milk cell-associated HIV-1 may not reflect plasma viral load. Nutritional value or possible bacterial contamination of milk treated in this manner was not assessed.     

Are cortisol concentrations in human breast milk associated with infant crying?

The present longitudinal study is the first to investigate the association between human breast milk cortisol and infant crying over the first three months of life. Higher concentrations of breast milk cortisol were expected to be differentially associated with fussing and crying in boys and girls. At 2, 6, and 12 weeks of infant age, mothers (N = 70) collected a morning sample of their milk and kept a 3‐day diary to measure infant fussing and crying. Cortisol was extracted and quantified from milk samples. Results showed that breast milk cortisol concentrations increased from 2 weeks through 12 weeks of infant age. Milk cortisol was unrelated to the total duration, frequency, and bout length of infant fussing and crying for both boys and girls. Directions for future research aiming to extend our knowledge on the biology of milk cortisol in relation to infant behavior and development are discussed.     

The relationship between ghrelin and adiponectin levels in breast milk and infant serum and growth of infants during early postnatal life

Ghrelin and adiponectin have been found in breast milk and are considered to take part in the regulation of growth and energy metabolism of infants. Our aims were to determine ghrelin and adiponectin levels in breast milk and serum samples of mothers and their infants, and to investigate the relationship between their levels and anthropometry of newborn infants during early postnatal life. Total and active ghrelin and adiponectin levels were studied in breast milk, and the serum samples of 25 healthy lactating women and their healthy fullterm infants were taken at the 1st and 4th months of life. Anthropometric measurements of infants were also performed during the study period. Breast milk and infant serum active ghrelin levels were found to be significantly increased at the 4th month of life compared with 1st month levels (p < 0.05). Maternal serum total ghrelin and infant serum adiponectin levels were found to be significantly reduced at the 4th month of life (p < 0.05). Breast milk active ghrelin levels were higher than the infant and maternal serum active ghrelin at the 1st and 4th months (p < 0.05). There was a negative significant correlation between the level of infant serum active ghrelin levels and BMI of infants at the 1st month. A positive significant correlation was found between the level of 1st month infant serum adiponectin levels and weight gain of infants during the study period. Fourth month infant serum adiponectin were also positively correlated with weight and BMI of infants at the 4th month and the weight gain during study period. There was a positive significant correlation between the level of 4th month breast milk active ghrelin and weight gain of infants during the study period. Ghrelin and adiponectin are involved in postnatal growth of infants. Ghrelin in breast milk also seems to be related to the growth of infants during early postnatal life. The sources of these peptides in breast milk are probably both maternal serum and breast tissue itself.     

Effect of DHA-containing formula on growth of preterm infants to 59 weeks postmenstrual age

Between May 1993, and September 1994, a randomized, blinded clinical trial was conducted to evaluate measures of growth and body composition in 63 (32 males; 31 females) healthy, low-birth-weight infants (940–2250 g) who were randomly assigned to an infant formula with docosahexaenoic acid (22:6n3, DHA, 0.2 wt%) from fish oil or to a control formula. A preterm formula with or without DHA was fed beginning at 7–10 days prior to hospital discharge through 43 weeks postmenstrual age (PMA). Then, from 43-59 weeks PMA, infants were fed a term infant formula with or without a corresponding amount of DHA. Growth (weight, length, head circumference), regional body fatness (triceps, subscapular, suprailiac skinfold thicknesses), circumferences (arm, abdominal, chest), and estimates of body composition determined by total body electrical conductivity (TOBEC) (fat-free mass [FFM]) were evaluated. Growth was slower in males fed the DHA formula. They had significantly (P < 0.05) smaller gains in weight, length, and head circumference between study enrollment to 59 weeks PMA than those fed the control formula. At 51 weeks PMA, males in the DHA group had significantly smaller head circumferences (P < 0.05) and lower FFM (P < 0.05). At 59 weeks PMA, males in the DHA group weighed less (P < 0.05), had shorter recumbent lengths (P < 0.01), smaller head circumferences (P < 0.05), and lower FFM (P < 0.01) than those fed the control formula. Energy intakes from formula (kcal/d), however, were lower at 51 weeks (P < 0.05) and 59 weeks (P < 0.05) PMA in males fed the DHA formula. Adjusted for body weight (kcal/kg/d), mean energy intakes from formula at 51 and 59 weeks PMA were not significantly different between feeding groups. The differences in recumbent length, head circumference, and FFM remained statistically significant after controlling for energy and protein intakes (P < 0.01). For all males, neither FFM nor total body fat (TBF), when expressed as a percentage of total body weight, differed significantly between feeding groups. Among females, there were no significant differences between the feeding groups in measures of growth, body composition, or energy intake. The results indicated that infant formula with fish oil containing DHA and EPA in a 5:1 ratio had a significant, negative effect on growth and body composition in males during the first 6 months of life. It is not clear why the growth deficits were limited to males and not females. The eicosanoids, bioactive metabolites of omega-3 and omega-6 fatty acids, may mediate several important growth hormones. The present results do not support the addition of DHA alone in infant formulas. Am. J. Hum. Biol. 11:457–467, 1999. © 1999 Wiley-Liss, Inc.     

Factors affecting breast milk composition and potential consequences for development of the allergic phenotype

There is conflicting evidence on the protective role of breastfeeding in relation to allergic sensitization and disease. The factors in breast milk which influence these processes are still unclear and under investigation. We know that colostrum and breast milk contain a variety of molecules which can influence immune responses in the gut‐associated lymphoid tissue of a neonate. This review summarizes the evidence that variations in colostrum and breast milk composition can influence allergic outcomes in the infant, and the evidence that maternal and environmental factors can modify milk composition. Taken together, the data presented support the possibility that maternal dietary interventions may be an effective way to promote infant health through modification of breast milk composition.     

Temporal and lateral dynamics of HIV shedding and elevated sodium in breast milk among HIV-positive mothers during the first 4 months of breast-feeding

OBJECTIVE: To better understand the dynamics of breast milk HIV shedding and its relation to postnatal HIV transmission, we investigated the temporal and lateral relations of breast milk viral shedding and sodium concentrations in HIV-positive women. DESIGN: This was a longitudinal cohort study in Lusaka, Zambia. METHOD: We examined patterns of HIV shedding in breast milk over the first 4 months of breast-feeding and their correlations with postnatal HIV transmission among 138 breast-feeding mothers. Sodium concentration in breast milk was also examined in the same samples and in breast milk from 23 HIV-negative controls. RESULTS: Higher breast milk viral load at 1 week, 1 month, and 4 months and consistent viral shedding in breast milk were significantly associated with increased risk of HIV transmission. Elevated breast milk sodium concentration (> or =13 mmol/L) at 4 months was associated with HIV transmission, low maternal CD4 cell count, and high maternal plasma viral load. Elevated sodium concentration at 1 week postpartum was common and was not associated with any of these parameters. CONCLUSIONS: Consistent viral shedding and high breast milk viral load are strong predictors of mother-to-child HIV transmission. Although sodium concentrations later in breast-feeding correlate with breast milk viral load, increased breast milk sodium is normal in early lactation and does not predict HIV transmission.     

Depressed Mothers' Neonates Improve Following the MABI and a Brazelton Demonstration

Objective: To assess the effectiveness of a short-term interventionfor improving interaction behaviors of newborn infants withtheir depressed mothers. Method: Depressed mothers assigned to the experimental groupfirst observed an administration of the Neonatal BehavioralAssessment Scale (NBAS) at delivery. Mothers then used a similarinstrument, the Mother's Assessment of the Behavior of her Infant(MABI), to independently conduct NBAS-like infant assessmentsperiodically at home. Depressed mothers in the control groupwere not present when the NBAS was administered at delivery,and they periodically completed written assessments at homeof their parenting attitudes and infants' development. Results: One month NBAS assessments administered by an examinerrevealed that experimental group infants performed more optimallythan controls on Social Interaction and State Organization. Conclusions: Findings suggested that an intervention consistingof mothers taking part in NBAS/MABI assessments may be a simpleand cost effective technique for benefiting infants of depressedmothers during the early postpartum period.     

Feeding mode, intestinal permeability, and neopterin excretion: a longitudinal study in infants of HIV-infected South African women

Exclusive breast feeding has been associated with a lower rate of mother-to-child HIV transmission than breast feeding plus other foods. To obtain further information on biologic outcomes of different feeding modes, we examined 272 infants of HIV-infected South African women at ages 1, 6, and 14 weeks. At each visit information about infant diet and morbidity was collected and infants underwent a lactulose/mannitol dual sugar intestinal permeability test. In a subset of infants, urinary neopterin excretion was measured as an indicator of immune system activation. Infants who had themselves become HIV-infected by 14 weeks had higher ( p <.01) intestinal permeability at 6 and 14 weeks and slightly (.05 < p <.1) higher neopterin excretion at all times than uninfected infants. At 1 week infants given no breast milk had higher ( p <.05) intestinal permeability than infants given breast milk exclusively or with other foods. Intestinal permeability in infants fed breast milk plus other foods was never increased relative to that of exclusively breastfed infants. Feeding mode had no effect on neopterin excretion. Thus, infant HIV infection induces changes in gut permeability and possibly immune system activation before clinical symptoms become apparent. The effects of feeding mode on infant intestinal permeability or urinary neopterin excretion do not explain a possible protective effect of exclusive breast feeding on mother-to-child transmission of HIV.     

Neurobehavioral symptoms in childhood closed-head injuries: changes in prevalence and correlates during the first year postinjury

OBJECTIVE: To examine changes in the prevalence and correlates of neurobehavioral symptoms during the first year following childhood closed-head injuries (CHIs). METHODS: Participants included 31 children with severe CHIs, 38 with moderate CHIs, and 53 with orthopedic injuries (OIs). Children and their families were assessed shortly after injury and at 6- and 12-month follow-ups. Parents rated 15 symptoms classified as either cognitive/somatic (C/S) or emotional/behavioral (E/B). RESULTS: Both kinds of symptoms were more common in the CHI groups than in the OI group. C/S symptoms declined in the CHI groups over time, whereas E/B symptoms became relatively more common. Measures of injury severity, children's premorbid behavioral adjustment, and concurrent cognitive functioning predicted C/S symptoms. E/B symptoms were predicted by injury severity, concurrent cognitive functioning soon after the injury, and concurrent parent and family functioning later in time. Both types of symptoms contributed to the prediction of perceived family burden, with the relationships strengthening over time. CONCLUSIONS: The findings indicate that the prevalence and correlates of neurobehavioral symptoms in childhood CHIs vary as a function of symptom type and time since injury.     

Cultivation-independent assessment of the bacterial diversity of breast milk among healthy women

Breast milk has been shown to be an excellent and continuous source of commensal and potentially probiotic bacteria to the infant gut. Our aim was to evaluate the dominant bacteria existing in breast milk of healthy women and the potential role of transit through the vagina in the acquisition of breast milk microbiota using the 16S rRNA amplified gene approach. Samples of breast milk were aseptically collected, at day 7 after delivery, from five mothers whose neonates were born by vaginal delivery and from five others who had had their babies by programmed elective cesarean section. All mothers were healthy, had a full-term pregnancy and breastfed their infants. DNA extracted from biological samples was used as a template for PCR amplification of 16S rRNA gene sequences with universal bacterial primers; then the PCR products were analyzed by denaturing gradient gel electrophoresis (DGGE); finally, clone libraries of 16S rRNA gene sequences from 4 mothers (2 from each group) were constructed. PCR DGGE patterns and clone libraries suggest that each woman had a specific bacterial pattern in her breast milk, and confirm, at the molecular level, that breast milk of healthy women is a source of commensal bacteria to the infant gut. They also reinforce recent molecular studies which have shown that lactic acid bacteria colonization is not significantly related to the delivery method.