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Background In a phase I/II study, a maternal respiratory syncytial virus vaccine candidate (RSVPreF3) demonstrated an acceptable safety profile and efficiently increased RSV-specific humoral immune responses in non-pregnant women. Methods In this phase II observer-blind, placebo-controlled, randomized clinical trial (NCT04126213), the safety of RSVPreF3 (60 or 120 µg), administered during late second or third trimester, was evaluated in 213 18-40-year-old healthy pregnant women through six months post-delivery and their offspring through infancy; immunogenicity was evaluated through day 43 post-delivery and day 181 post-birth, respectively. Results RSVPreF3 was well tolerated. No pregnancy-related or neonatal adverse events of special interest were considered vaccine/placebo-related. In the 60 and 120 µg RSVPreF3 groups: (i) neutralizing antibody (nAb) titers in mothers increased 12.7- and 14.9-fold against RSV-A and 10.6- and 13.2-fold against RSV-B, respectively, one month post-vaccination and remained 8.9–10.0-fold over pre-vaccination at day 43 post-delivery, (ii) nAb titers were consistently higher compared to placebo recipients, (iii) placental transfer ratios for anti-RSVPreF3 antibodies at birth were 1.62 and 1.90, respectively, and (iv) nAb levels in infants were highest at birth and declined through day 181 post-birth. Conclusions RSVPreF3 maternal vaccination had an acceptable safety risk profile and induced robust RSV-specific immune responses with successful antibody transfer to their newborns.

Objective To evaluate the perinatal and maternal outcomes of pregnancies in SARS-CoV-2 infected women, comparing spontaneous and In Vitro Fertilization (IVF) pregnancies (with either own or donor oocytes). Design Multicentre, prospective, observational study. Setting 78 centres participating in the Spanish COVID19 Registry. Patients 1,347 SARS-CoV-2 positive pregnant women registered consecutively between February 26 th and November 5 th , 2020. Interventions Patient´s information was collected from their medical records, and multivariable regression analyses were performed, controlling for maternal age and the clinical presentation of infection. Main outcome measures Obstetrics and neonatal outcomes, pregnancy comorbidities, intensive care unit admission, mechanical ventilation need and medical conditions. Results The IVF group was composed of 74 (5.5%) women whereas the spontaneous group included 1,275 (94.5%) women. Operative delivery rate was high in all patients, especially in the IVF group, where C-section became the most frequent method of delivery (55.4%, compared to 26.1% of spontaneous). The reason for C-section was induction failure in 56.1% of IVF patients. IVF women had more gestational hypertensive disorders [16.2% vs 4.5% among spontaneous, adjusted Odds Ratio (aOR) 5.31, 95% Confidence Interval (CI) 2.45-10.93) irrespective of oocyte origin. The higher rate of ICU admittance observed in the IVF group (8.1% vs 2.4% spontaneous) was attributed to pre-eclampsia (aOR 11.82, 95% CI 5.25-25.87), not to the type of conception, Conclusions High rate of operative delivery has been observed in SARS-CoV-2 infected women, especially in IVF pregnancies; method of conception does not affect foetal or maternal outcomes, except for pre-eclampsia.

Objectives: Human pregnancy is associated with important physiological changes that usually increase energetic requirements. However, great variability exists in the costs and mechanisms required to bear pregnancy. Since body mass (BM) and composition are modified during gestation, it is of great interest to compare the influence of BM on energy expenditure (EE) in pregnant and nonpregnant females.Methods: BM, body composition, and EE of 77 volunteers (35 pregnant and 42 nonpregnant females) were measured. The pregnant volunteers completed two measurement rounds at 28 and 32 gestation weeks. Differences on the measured parameters were sought, and comparison of regression lines was computed to test how BM affected the EE of the volunteers.Results: BM and body composition parameters are significantly higher in pregnant females, but EE is not statistically different. Pregnant females have a larger percentage of fat mass, but lower percentage of fat-free mass (FFM). The EE per kg of FFM is similar in both groups. Comparison of regression lines shows that pregnancy does not change the relationship between BM and EE, but for similar BM pregnant females expend less energy than nonpregnant females. Conclusions: We propose that their larger percentage of passive body tissues is the reason why pregnant females expend less energy than nonpregnant females of similar BM, without changing the scaling of EE on BM. Thus, pregnancy could not be as energetically constraining as usually assumed, with important consequences for human reproductive ecology.