Objective: To quantify the transplacental transmission of SARS-CoV-2 and antibodies in pregnant women and their new-borns according to the trimester of maternal infection. Design: This was a prospective observational multicentre study including pregnant women with positivity for SARS-CoV-2 by reverse transcription–polymerase chain reaction (RT‒PCR) or positivity by serology from April to December 2020. The study was designed to perform a systematic collection of mother/new-born dyad samples at birth. Setting: Eleven maternity wards in Eastern France Population: Pregnant women with confirmed COVID-19 infection during pregnancy and their new-borns. Methods: The SARS-CoV-2 viral load was measured by RT‒PCR. IgG and IgM antibodies to the receptor-binding domain of the SARS-CoV-2 spike protein were measured by enzyme-linked immunosorbent assay. Antibody concentrations and transplacental transfer ratios were analysed according to the term of maternal infection. Main Outcome Measure: SARS-CoV-2 viral load in maternal plasma or respiratory fluids and umbilical cord plasma and quantification of anti-SARS-CoV-2 antibody transfer. Results: Among 165 dyads enrolled, one congenital infection was confirmed (n=1 (0.63%) IC95% [0.02%; 3.48%]). Among 165 maternal sera tested, 107 (64.8%) were positive for IgG with a concentration > 25.6 BAU/ml. The average placental transfer ratio was 1.27 (95% CI [0.69–2.89]). The transfer ratio increased with increasing time between the onset of maternal infection and delivery (P value = 0.0001). Conclusions: We confirmed very low SARS-CoV-2 transplacental transmission of less than 1%. Transmission of antibodies is more likely when the infection occurs in the first or second trimester of pregnancy.

Objective To identify risk factors strongly associated with failed mid-cavity vacuum-assisted delivery (VAD) and construct a risk model that can be used to guide obstetricians in choosing between the standard delivery room or the operating theatre. Design Observational analytical predictive prospective monocentric study. Setting University Hospital of Besançon, France, 2010-2018. Population All successful (n=903) and failed (n=194) attempts at mid-cavity VAD among term singleton deliveries. Methods Bivariate and multivariate analyses with logistic regression were used to determine the effects of 15 potential factors on the risk of VAD failure. Main outcome measures Mode of delivery following an attempt at mid-cavity VAD. Results The score comprised seven variables significantly associated with failed mid-cavity VAD: head-perineum distance ≥51 mm (p<0.001), bulky caput succedaneum (p<0.001), maternal height ≤1.54 m (p<0.001), duration of expulsive efforts before vacuum <21 minutes or >30 minutes (p=0.0013), duration from five centimetres to complete cervical dilation ≥3 hours (p=0.0091), term ≥42 weeks of gestation (p=0.032), and occiput-posterior or occiput-transverse fetal head position (p=0.041). The model was reliable (Hosmer-Lemeshow test =8.5; p=0.39) and accurate (concordance index =0.74). The threshold for a transfer to the operating theatre was set at 16.3 %. Advanced preparation of caesarean section equipment and anticipated extension of epidural analgesia were significantly associated with a decrease in the delay between VAD failure and birth by caesarean section (p<0.001). Conclusions This model could help obstetricians to better assess the risk of failed mid-cavity VAD and to choose the appropriate place to perform it. Keywords Vacuum-assisted delivery; mid-cavity.