Anti-SARS-CoV-2 antibodies in breast milk during lactation after infection or vaccination: A cohort study.

Breast milk is a pivotal source to provide passive immunity in newborns over the first few months of life. Very little is known about the antibody transfer levels over the period of breastfeeding. We conducted a prospective study in which we evaluated concentrations of anti-SARS-CoV-2 Spike IgA and RBD IgG/M/A antibodies in maternal serum and breast milk over a duration of up to 6 months after delivery. We compared antibody levels in women with confirmed COVID-19 infection during pregnancy (n = 16) to women with prenatal SARS-CoV-2 vaccination (n = 5). Among the recovered women, n = 7 (44%) had been vaccinated during the lactation period as well. We observed intraindividual moderate positive correlations between antibody levels in maternal serum and breast milk (r = 0.73, p-value<0.0001), whereupon the median levels were generally higher in serum. Anti-RBD IgA/M/G transfer into breast milk was significantly higher in women recovered from COVID-19 and vaccinated during lactation (35.15 AU/ml; IQR 21.96-66.89 AU/ml) compared to the nonvaccinated recovered group (1.26 AU/ml; IQR 0.49-3.81 AU/ml), as well as in the vaccinated only group (4.52 AU/ml; IQR 3.19-6.23 AU/ml). Notably, the antibody level in breast milk post SARS-CoV-2 infection sharply increased following a single dose of vaccine. Breast milk antibodies in all groups showed neutralization capacities against an early pandemic SARS-CoV-2 isolate (HH-1) and moreover, also against the Omicron variant, although with lower antibody titer. Our findings highlight the importance of booster vaccinations especially after SARS-CoV-2 infection in pregnancy in order to optimize protection in mother and newborn.

Maternal nutrition, inadequate gestational weight gain and birth weight: results from a prospective birth cohort.

BACKGROUND: The aim of our study was to examine maternal weight gain as well as nutrient intake in pregnancy throughout each trimester compared to current recommendations in a low-risk population and its correlation to birth weight. Additionally, we have investigated the association of maternal nutrition with gestational weight gain and birth weight in an economically unrestricted population. METHODS: Our analysis was carried out in a population-based prospective birth cohort in Hamburg, Germany. 200 pregnant women and 197 infants born at term were included in the analysis. Maternal body weight, weight gain throughout gestation, and birth weight, macro- and micronutrients were assessed based on a 24 h dietary recall in each trimester. Our main outcome measures were weight gain, birth weight, and self-reported dietary intake in each trimester in comparison to current recommendations. RESULTS: One third of the women were characterized by an elevated pre-pregnancy BMI, 60 % did not comply with current weight gain recommendations. Particularly overweight and obese women gained more weight than recommended. In a multivariate analysis birth weight correlated significantly with maternal BMI (p = 0.020), total weight gain (p = 0.020) and gestational week (p < 0.001). Compared to guidelines mean percentage of energy derived from fat (p = 0.002) and protein (p < 0.001) was significantly higher, whereas carbohydrate (p = 0.033) intake was lower. Mean fiber intake was significantly lower (p < 0.001). Saturated fat and sugar contributed largely to energy consumption. Gestational weight gain correlated significantly with energy (p = 0.027), carbohydrates (p = 0.008), monosaccharides and saccharose (p = 0.006) intake. 98 % of the pregnant women were below the iodine recommendation, while none of the women reached the required folate, vitamin D, and iron intake. CONCLUSIONS: During gestation appropriate individual advice as to nutrient intake and weight gain seems to be of high priority. Pregnancy should be used as a 'window of opportunity' for behavioral changes.

Fetal thymus size in human pregnancies reveals inverse association with regulatory T cell frequencies in cord blood.

OBJECTIVE: To determine fetal thymus growth and its relationship with fetal weight and cord blood T-regulatory cells in a prospective study. Assessment of fetal immune organs by ultrasound could provide a screening approach to identify fetuses at risk of impaired postnatal immunity. STUDY DESIGN AND OUTCOME MEASURES: Thymus size was measured with four ultrasound techniques. The approaches with lowest coefficient of variation (thymus transverse diameter, 3 vessel edge) were used to longitudinally assess fetal and thymus growth in 137 cases at four time points between a gestational age (GA) of 13 and 37 weeks. Cord blood at birth was analyzed by flow-cytometry to evaluate the frequency of regulatory T (Treg) cells. RESULTS AND CONCLUSION: Fetal thymus growth is significantly correlated with fetal weight (GA 23-25 weeks r=0.40, p<0.01; GA 28-30 weeks r=0.21, p=0.04, GA 35-37 weeks r=0.56, p<0.01). We observed an inverse correlation between fetal thymus size at GA 23-25 weeks and cord blood Treg cells (r=0.37, p=0.01). Thymus growth occurs in a linear fashion throughout pregnancy and can be reliably measured using ultrasound. Our findings of an inverse correlation between thymus growth and Treg cells in cord blood suggests a link between fetal growth, thymus development and immune-status at birth.