Background Pregnant and lactating women were excluded from initial COVID-19 vaccine trials; thus, data to guide vaccine decision-making are lacking. Objectives To evaluate the immunogenicity and reactogenicity of COVID-19 mRNA vaccination in pregnant and lactating women compared to: (1) non-pregnant controls and (2) natural COVID-19 infection in pregnancy. Study Design 131 reproductive-age vaccine recipients (84 pregnant, 31 lactating, and 16 non-pregnant) were enrolled in a prospective cohort study at two academic medical centers. Titers of SARS-CoV-2 Spike and RBD IgG, IgA and IgM were quantified in participant sera (N=131) and breastmilk (N=31) at baseline, second vaccine dose, 2-6 weeks post second vaccine, and at delivery by Luminex. Umbilical cord sera (N=10) titers were assessed at delivery. Titers were compared to those of pregnant women 4-12 weeks from natural infection (N=37) by ELISA. A pseudovirus neutralization assay was used to quantify neutralizing antibody titers for the subset of women who delivered during the study period. Post-vaccination symptoms were assessed via questionnaire. Kruskal-Wallis tests and a mixed effects model, with correction for multiple comparisons, were used to assess differences between groups. Results Vaccine-induced antibody titers were equivalent in pregnant and lactating compared to non-pregnant women (median [IQR] 5.59 [4.68-5.89] pregnant, 5.74 [5.06-6.22] lactating, 5.62 [4.77-5.98] non-pregnant, p = 0.24). All titers were significantly higher than those induced by SARS-CoV-2 infection during pregnancy (p < 0.0001). Vaccine-generated antibodies were present in all umbilical cord blood and breastmilk samples. Neutralizing antibody titers were lower in umbilical cord compared to maternal sera, although this finding did not achieve statistical significance (median [IQR] 104.7 [61.2-188.2] maternal sera, 52.3 [11.7-69.6] cord sera, p=0.05). The second vaccine dose (boost dose) increased SARS-CoV-2-specific IgG, but not IgA, in maternal blood and breastmilk. No differences were noted in reactogenicity across the groups. Conclusions COVID-19 mRNA vaccines generated robust humoral immunity in pregnant and lactating women, with immunogenicity and reactogenicity similar to that observed in non-pregnant women. Vaccine-induced immune responses were significantly greater than the response to natural infection. Immune transfer to neonates occurred via placenta and breastmilk.

Key Points Question What key biological characteristics of maternal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and placental function and pathology have implications for vertical transmission and neonatal protection? Findings In this prospective cohort study including 127 pregnancies, there was no maternal viremia, placental infection, or vertical transmission of SARS-CoV-2. Compromised transplacental transfer of anti–SARS-CoV-2 antibodies with robust transfer of influenza-specific immunity and nonoverlapping placental expression of SARS-CoV-2 receptors angiotensin-converting enzyme 2 and transmembrane serine protease 2 were noted. Meaning These findings suggest that, although low rates of maternal viremia and patterns of placental SARS-CoV-2 receptor distribution may underlie the rarity of vertical transmission, reduced transplacental transfer of anti–SARS-CoV-2 antibodies may leave neonates at risk for infection.

SARS-CoV-2 infection causes more severe disease in pregnant women compared to age-matched non-pregnant women. Whether maternal infection causes changes in the transfer of immunity to infants remains unclear. Maternal infections have previously been associated with compromised placental antibody transfer, but the mechanism underlying this compromised transfer is not established. Here, we used systems serology to characterize the Fc-profile of influenza-, pertussis-, and SARS-CoV-2-specific antibodies transferred across the placenta. Influenza- and pertussis-specific antibodies were actively transferred. However, SARS-CoV-2-specific antibody transfer was significantly reduced compared to influenza- and pertussis-specific antibodies, and cord titers and functional activity were lower than in maternal plasma. This effect was only observed in third trimester infection. SARS-CoV-2-specific transfer was linked to altered SARS-CoV-2-antibody glycosylation profiles and was partially rescued by infection-induced increases in IgG and increased FCGR3A placental expression. These results point to unexpected compensatory mechanisms to boost immunity in neonates, providing insights for maternal vaccine design.

Background: Pregnant and lactating women were excluded from initial COVID-19 vaccine trials; thus, data to guide vaccine decision-making are lacking. We sought to evaluate the immunogenicity and reactogenicity of COVID-19 mRNA vaccination in pregnant and lactating women. Methods: 131 reproductive-age vaccine recipients (84 pregnant, 31 lactating, and 16 non-pregnant) were enrolled in a prospective cohort study at two academic medical centers. Titers of SARS-CoV-2 Spike and RBD IgG, IgA and IgM were quantified in participant sera (N=131), umbilical cord sera (N=10), and breastmilk (N=31) at baseline, 2nd vaccine dose, 2-6 weeks post 2nd vaccine, and delivery by Luminex, and confirmed by ELISA. Titers were compared to pregnant women 4-12 weeks from native infection (N=37). Post-vaccination symptoms were assessed. Kruskal-Wallis tests and a mixed effects model, with correction for multiple comparisons, were used to assess differences between groups. Results: Vaccine-induced immune responses were equivalent in pregnant and lactating vs non-pregnant women. All titers were higher than those induced by SARS-CoV-2 infection during pregnancy. Vaccine-generated antibodies were present in all umbilical cord blood and breastmilk samples. SARS-CoV-2 specific IgG, but not IgA, increased in maternal blood and breastmilk with vaccine boost. No differences were noted in reactogenicity across the groups. Conclusions: COVID-19 mRNA vaccines generated robust humoral immunity in pregnant and lactating women, with immunogenicity and reactogenicity similar to that observed in non-pregnant women. Vaccine-induced immune responses were significantly greater than the response to natural infection. Immune transfer to neonates occurred via placental and breastmilk.

Fetal placental macrophages and microglia (resident brain macrophages) have a common origin in the fetal yolk sac. Yolk‐sac‐derived macrophages comprise the permanent pool of brain microglia throughout an individual's lifetime. Inappropriate fetal microglial priming may therefore have lifelong neurodevelopmental consequences, but direct evaluation of microglial function in a living fetus or neonate is impossible. We sought to test the hypothesis that maternal obesity would prime both placental macrophages and fetal brain microglia to overrespond to an immune challenge, thus providing a window into microglial function using placental cells. Obesity was induced in C57BL/6 J mice using a 60% high‐fat diet. On embryonic day 17.5, fetal brain microglia and corresponding CD11b + placental cells were isolated from fresh tissue. Cells were treated with media or lipopolysaccharide (LPS). Tumor necrosis factor‐alpha (TNF‐α) production by stimulated and unstimulated cells was quantified via ELISA. We demonstrate for the first time that the proinflammatory cytokine production of CD11b + placental cells is strongly correlated with that of brain microglia (Spearman's ρ = 0.73, p = 0.002) in the setting of maternal obesity. Maternal obesity‐exposed CD11b + cells had an exaggerated response to LPS compared to controls, with a 5.1‐fold increase in TNF‐α production in placentas (p = 0.003) and 3.8‐fold increase in TNF‐α production in brains (p = 0.002). In sex‐stratified analyses, only male obesity‐exposed brains and placentas had significant increase in TNF‐α production in response to LPS. Taken together, these data suggest that maternal obesity primes both placental macrophages and fetal brain microglia to overproduce a proinflammatory cytokine in response to immune challenge. Male brain and placental immune response is more marked than female in this setting. Given that fetal microglial priming may impact neuroimmune function throughout the lifespan, these data could provide insight into the male predominance of certain neurodevelopmental morbidities linked to maternal obesity, including cognitive dysfunction, autism spectrum disorder, and ADHD. Placental CD11b+ macrophages may have the potential to serve as an accessible biomarker of aberrant fetal brain immune activation in maternal obesity. This finding may have broader implications for assaying the impact of other maternal exposures on fetal brain development.

Objectives To assess whether late surfactant treatment of extremely low gestational age newborn (ELGAN) infants requiring ventilation at 7–14 days, who often have surfactant deficiency and dysfunction, safely improves survival without bronchopulmonary dysplasia (BPD). Study design ELGAN infants (≤ 28 0/7 weeks) who required mechanical ventilation at 7–14 days were enrolled in a randomized, masked controlled trial at 25 US centers. All infants received inhaled nitric oxide (INO) and either surfactant (calfactant/Infasurf®) or sham instillation every 1–3 days to a maximum of 5 doses while intubated. The primary outcome was survival at 36 weeks postmenstrual age (PMA) without BPD, evaluated by physiologic oxygen/flow reduction. Results Between January 2010 and September 2013, 511 infants were enrolled. There were no differences between treatment groups in mean birth weight (701±164 g), gestational age (25.2±1.2 weeks), percentage <26 weeks (70.6%), race, sex, severity of lung disease at enrollment, or co-morbidities of prematurity. Survival without BPD was not different between treated vs. controls at 36 weeks PMA (31.3% vs. 31.7%; relative benefit 0.98 (95% CI: 0.75, 1.28 p=0.89) or 40 weeks (58.7% vs. 54.1%; relative benefit 1.08:0.92, 1.27 p=0.33). There were no differences between groups in serious adverse events, co-morbidities of prematurity, nor in the severity of lung disease to 36 weeks. Conclusions Late treatment with up to 5 doses of surfactant in ventilated premature infants receiving iNO was well tolerated but did not improve survival without BPD at 36 or 40 weeks. Pulmonary and neurodevelopmental assessments are ongoing.

Maternal SARS-CoV-2 infection drives sexually dimorphic placental immune responses and reduces SARS-CoV-2–specific antibody transfer to male fetuses.

OBJECTIVE: To identify the association of the Affordable Care Act's Medicaid expansion with payment for delivery, early access to prenatal care, preterm birth, and birth weights considered small for gestational age (SGA). METHODS: A difference-in-difference design was used to assess changes in outcomes before and after Medicaid expansion in expansion states, using nonexpansion states as a control group. We used national birth certificate data from 2009 to 2017. Difference-in-difference linear probability models were used to assess the effects of the policy implementation, adjusting for demographics, month of birth, state, year, and county-level unemployment rates. Standard errors were clustered at the state level. Two prespecified subgroup analyses were performed of nulliparous women and women with no more than a high school diploma. RESULTS: The study sample included 8,701,889 women from 15 expansion states and 9,509,994 from 11 nonexpansion states. In the adjusted analysis, the percentage of Medicaid-covered deliveries increased by 2.3 absolute percentage points (95% CI 0.2–4.4, P=.04) in expansion states compared with nonexpansion states. There were no significant changes in the proportion of women who were uninsured, as there was a relative decrease in the percentage of deliveries covered by private insurance (−2.8 percentage points [95% CI −4.9 to −0.8, P=.01]). There were also no significant differences in the rate of women initiating prenatal care in the first trimester, preterm birth rates, or rates of low birth weight after the Medicaid expansion. Findings were similar in both subgroups. CONCLUSION: Medicaid expansion was associated with increased Medicaid coverage for childbirth in expansion states; similar gains in private coverage were seen in nonexpansion states. There were no associations with changes in early access to prenatal care, preterm birth, or SGA birth weights.