Hispanic race is a risk factor for COVID-19 during pregnancy: data from an urban New York City hospital.

There are limited studies on predisposing factors for COVID-19 positivity in asymptomatic pregnant women. The literature published to date on asymptomatic COVID-19 pregnant carriers does not focus on pregnancy or pre-pregnancy comorbidities. We wanted to identify risk factors for COVID-19 in asymptomatic pregnant women. We performed a retrospective chart review of 263 asymptomatic pregnant women admitted to labour and delivery at New York City Health + Hospitals/Lincoln.We analysed the association between race, body mass index (BMI), smoking, indication for admission, gravidity, parity, pre-pregnancy comorbidity, pregnancy comorbidity via uni- and multivariate statistical tests. Only Hispanic race was significant in the univariate analysis (p = .049). At the post-hoc analysis, Hispanics had a higher proportion of COVID-19 cases compared to non-Hispanic Blacks (p = .019). No variables were significantly associated with COVID-19 positivity in the multivariate analysis.Hispanic race appears to be a risk factor for asymptomatic COVID-19 infection during pregnancy. We speculate that the cultural and socioeconomic reality of Hispanic women living in our community leads to more exposure opportunities and therefore, a higher infection rate.Impact statementWhat is already known on this subject? Little is known on the role of comorbidities and risk factors that can favour COVID-19 infection during pregnancy.What do the results of this study add? We found that Hispanic pregnant asymptomatic women had a higher rate of COVID-19 in comparison to non-Hispanic Black women. Pre-pregnancy comorbidities such as pregestational diabetes, hypertension and asthma were not associated with COVID-19 positivity.What are the implications of these findings for clinical practice and/or further research? The reasons why the Hispanic race is more affected by COVID-19 during pregnancy is unclear. The social environment of Hispanic women living in our community, such as their tendency to live in multigenerational and multi-family households, might contribute to a higher infection rate. More resources might be dedicated in the future to Hispanic-dense neighbourhoods.

Serine racemase and D-serine transport in human placenta and evidence for a transplacental gradient for D-serine in humans.

OBJECTIVE: To investigate the possible role of human placenta in providing D-serine to the developing fetus. METHODS: Expression of serine racemase in placenta was determined by reverse transcriptase polymerase chain reaction and northern analysis and confirmed by subsequent cloning. The transport of D-serine by human ATB(0) was characterized by expressing the cloned cDNA transiently in mammalian cells using the vaccinia virus expression system. D-serine levels in maternal and fetal blood were measured by fluorescence high-performance liquid chromatography (HPLC) after derivatization of the amino acids with o-phthaldialdehyde and N-tertiary-butyloxycarbonyl-L-cysteine. RESULTS: mRNA for serine racemase was detected in placenta. ATB(0) was capable of d-serine transport, and the transport process is obligatorily dependent on sodium (Na+) with a Na(+):substrate stoichiometry of 1:1 and saturable with a Michaelis-Menten constant of 310 +/- 30 microM. Furthermore, studies have shown that ATB(0) is not expressed in the maternal-facing brush border membrane of human placental syncytiotrophoblast. The circulating concentration of D-serine in maternal serum is 5.8 +/- 0.5 microM, and the corresponding value in the fetal serum is 14.6 +/- 1.2 microM, indicating a two- to three-fold higher concentration of D-serine in the fetus than in the mother. CONCLUSION: We speculate that D-serine is synthesized in human placenta by the racemization of L-serine and that ATB(0), expressed on the basal membrane of the syncytiotrophoblast, mediates the efflux of D-serine into the fetal circulation in exchange for other amino acids in fetal blood.

Inhibition of system A amino acid transport activity by ethanol in BeWo choriocarcinoma cells.

OBJECTIVE: Our purpose was to investigate the influence of ethanol on system A amino acid transporter in BeWo cells. STUDY DESIGN: BeWo cells were cultured in the absence or presence of ethanol. The function of system A was monitored by the transport of alpha-(methylamino)isobutyric acid. Messenger RNA levels for system A were assessed by Northern analysis. RESULTS: Treatment of BeWo cells with ethanol reduced the activity of system A. The effect was dose and treatment time dependent. The decrease in system A activity was 38% +/- 3% at 0.75% ethanol with a 16-hour treatment time. The activities of several other transporters tested were not affected. The effect on system A activity was associated with a decrease in the maximal velocity of the transport system without affecting the substrate affinity. Ethanol did not alter the messenger RNA levels for system A. CONCLUSION: Exposure of BeWo cells to ethanol significantly reduces the function of system A. This finding has potential implications that may be relevant to the pathogenesis of the fetal alcohol syndrome.