SARS-CoV-2 antibodies and their neutralizing capacity against live virus in human milk after COVID-19 infection and vaccination: prospective cohort studies.

BACKGROUND: There is limited understanding of the impact of coronavirus disease 2019 (COVID-19) infection and vaccination type and interval on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) human milk antibodies and their neutralizing capacity. OBJECTIVES: These cohort studies aimed to determine the presence of antibodies and live virus neutralizing capacity in milk from females infected with COVID-19, unexposed milk bank donors, and vaccinated females and examine impacts of vaccine interval and type. METHODS: Milk was collected from participants infected with COVID-19 during pregnancy or lactation (Cohort-1) and milk bank donors (Cohort-2) from March 2020-July 2021 at 3 sequential 4-wk intervals and COVID-19 vaccinated participants with varying dose intervals (Cohort-3) (January-October 2021). Cohort-1 and Cohort-3 were recruited from Sinai Health (patients) and through social media. Cohort-2 included Ontario Milk Bank donors. Milk was examined for SARS-CoV-2 antibodies and live virus neutralization. RESULTS: Of females with COVID-19, 53% (Cohort-1, n = 55) had anti-SARS-CoV-2 IgA antibodies in ≥1 milk sample. IgA+ samples (40%) were more likely neutralizing than IgA- samples (odds ratio [OR]: 2.18; 95% confidence interval [CI]: 1.03, 4.60; P = 0.04); however, 25% of IgA- samples were neutralizing. Both IgA positivity and neutralization decreased ∼6 mo after symptom onset (0-100 compared with 201+ d: IgA OR: 14.30; 95% CI: 1.08, 189.89; P = 0.04; neutralizing OR: 4.30; 95% CI: 1.55, 11.89; P = 0.005). Among milk bank donors (Cohort-2, n = 373), 4.3% had IgA antibodies; 23% of IgA+ samples were neutralizing. Vaccination (Cohort-3, n = 60) with mRNA-1273 and shorter vaccine intervals (3 to <6 wk) resulted in higher IgA and IgG than BNT162b2 (P < 0.04) and longer intervals (6 to <16 wk) (P≤0.02), respectively. Neutralizing capacity increased postvaccination (P = 0.04) but was not associated with antibody positivity. CONCLUSIONS: SARS-CoV-2 infection and vaccination (type and interval) impacted milk antibodies; however, antibody presence did not consistently predict live virus neutralization. Although human milk is unequivocally the best way to nourish infants, guidance on protection to infants following maternal infection/vaccination may require more nuanced messaging. This study was registered at clinicaltrials.gov as NCT04453969 and NCT04453982.

Characteristics of vulnerable women and their association with participation in a Canada Prenatal Nutrition Program site in Toronto, Canada. / Caractéristiques de femmes vulnérables en lien avec leur participation aux activités d'un centre du Programme canadien de nutrition prénatale à Toronto (Canada).

INTRODUCTION: The Canada Prenatal Nutrition Program (CPNP) supports community organizations to provide maternal-infant health services for socially/economically vulnerable women. As part of our research program exploring opportunities to provide postnatal breastfeeding support through the CPNP, we investigated the sociodemographic and psychosocial characteristics of clients enrolled in a Toronto CPNP site and explored associations with participation. METHODS: Data were collected retrospectively from the charts of 339 women registered in one southwest Toronto CPNP site from 2013 to 2016. Multivariable regression analyses were used to assess associations between 10 maternal characteristics and three dimensions of prenatal program participation: initiation (gestational age at enrolment in weeks), intensity (number of times one-on-one supports were received) and duration (number of visits). RESULTS: The mean (SD) age of clients was 31 (5.7) years; 80% were born outside of Canada; 29% were single; and 65% had household incomes below the Statistics Canada family size-adjusted low-income cut-offs. Income was the only characteristic associated with all dimensions of participation. Compared to clients living above the low-income cut-off, those living below the low-income cut-off enrolled in the program 2.85 weeks earlier (95% CI: -5.55 to -0.16), had 1.29 times higher number of one-on-one supports (95% CI: 1.03 to 1.61) and had 1.29 times higher number of program visits (95% CI: 1.02 to 1.63). CONCLUSION: Our findings show that this CPNP site serves vulnerable women, with few differences in participation based on maternal characteristics. This evidence can guide service provision and monitoring decisions at this program site. Further research is needed to explore new program delivery models to enhance perinatal services for vulnerable women.

Breastfeeding rates are high in a prenatal community support program targeting vulnerable women and offering enhanced postnatal lactation support: a prospective cohort study.

BACKGROUND: In Canada, 91% of all mothers initiate breastfeeding, but 40-50% stop by 6 months and only 34% breastfeed exclusively for 6 months, with lower rates among socially and/or economically vulnerable women. The Canada Prenatal Nutrition Program (CPNP) aims to support breastfeeding among vulnerable women, but there is no formal framework or funding for sites to integrate proactive postnatal breastfeeding support. This research aimed to i) describe infant feeding practices among clients of one Toronto CPNP site using charitable funds to offer a lactation support program (in-home lactation consultant visits, breast pumps); ii) determine whether breastfeeding outcomes at 6 months differ based on maternal sociodemographics and food insecurity; and iii) assess utilization of the lactation support program. METHODS: Infant feeding practices were collected prospectively at 2 weeks, 2, 4 and 6 months postpartum via telephone questionnaires (n = 199). Maternal sociodemographics were collected at 2 weeks and food insecurity data at 6 months postpartum. Program monitoring records were used to determine utilization of the lactation support program. RESULTS: Ninety-one percent of participants were born outside of Canada; 55% had incomes below the Low-Income Cut-Off; and 55% reported food insecurity. All participants initiated breastfeeding, 84% continued for 6 months and 16% exclusively breastfed for 6 months. Among breastfed infants, ≥76% received vitamin D supplementation. Approximately 50% of infants were introduced to solids before 6 months. Only high school education or less and food insecurity were associated with lower breastfeeding rates. Overall, 75% of participants received at least one visit with a lactation consultant and 95% of these received a breast pump. CONCLUSIONS: This study provides initial evidence that postnatal lactation support can be delivered within a CPNP site, with high uptake by clients. While all participants initiated breastfeeding and 84% continued for 6 months, adherence to the recommended 6 months of exclusive breastfeeding was low. Further research is needed to better understand the barriers to exclusive breastfeeding and how to support this practice among vulnerable women. Study registered at clinicaltrials.gov as NCT03400605 .

Maternal BMI is positively associated with human milk fat: a systematic review and meta-regression analysis.

BACKGROUND: Lack of robust estimates of human-milk nutrient composition and influential maternal factors, such as body composition, are barriers to informing nutrition policies and programs. OBJECTIVE: The objective was to understand the relation between maternal BMI and human-milk energy, fat, and/or total protein. METHODS: Four electronic databases (MEDLINE, Embase, CINAHL, and Web of Science) were searched. Outcomes assessed were human-milk energy (kcal/L), fat (g/L), and total protein (g/L) from mothers 1 to 6 mo postpartum. Studies with data on maternal BMI or weight and height that quantified human-milk energy, fat, or protein between 1 and 6 mo postpartum were eligible. Random-effects meta-regression weighted by the inverse of the study-level SE was completed for each of the 3 outcomes. The certainty of evidence for each outcome was assessed using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach. RESULTS: A total of 11,373 titles and abstracts were identified, and after full-text screening, 69 articles of 66 studies were included. Meta-regression results showed a positive association between maternal BMI and human-milk fat (ß: 0.56 g/L; 95% CI: 0.034, 1.1; P = 0.04; I2 = 93.7%, n = 63 datapoints). There was no significant association between maternal BMI and human-milk energy (ß: 3.9 kcal/L; 95% CI: -1.6, 9.5; P = 0.16, I2 = 93.3%, n = 40 datapoints) or total protein (ß: 0.13 g/L; 95% CI: -0.16, 0.41; P = 0.37, I2 = 99.1%, n = 40 datapoints). The certainty of evidence for human-milk energy was low and the certainty of evidence for fat and total protein was very low. CONCLUSIONS: Meta-regression analysis of available literature suggested an association between maternal BMI and human-milk fat between 1 and 6 mo postpartum. Future studies are needed to confirm the relation between maternal BMI; variation in human-milk energy, fat, and protein content; and the implications for child growth and development. This review is registered with International Prospective Register of Systematic Reviews (PROSPERO 2018 CRD42018098808) at https://www.crd.york.ac.uk/prospero/.