Influenza vaccination prevented influenza cases and hospitalizations and was associated with a better prognosis in inpatients with influenza. The combined effect of these 2 mechanisms would explain the high effectiveness of the vaccine in preventing severe cases due to influenza.

OBJECTIVE:To investigate the association between twin pregnancy and severe acute maternal morbidity, overall and by timing (before, during or after delivery) and underlying causal condition. METHODS:We conducted a cohort-nested case-control analysis from the EPIMOMS prospective study conducted in six French regions from 2012-2013 (N5182,309 deliveries). The case group comprised 2,500 women with severe acute maternal morbidity (defined by a national expert consensus process) occurring from 22 weeks of gestation and up to 42 days postpartum. A random sample of 3,650 women who gave birth without severe acute maternal morbidity made up the control group. The association between twin pregnancy and severe acute maternal morbidity was analyzed with multilevel multivariable logistic regression. The role of cesarean delivery as an intermediate factor between twin pregnancy and severe acute maternal morbidity was assessed by path analysis. RESULTS:The population-based incidence of severe acute maternal morbidity was 6.2% (n5197/3,202, 95% CI 5.3-7.1) in twin pregnancies, and 1.3% (n52,303/ 179,107, 95% CI 1.2-1.3) in singleton pregnancies. After controlling for confounders, the risk of severe acute maternal morbidity was higher in twin than in singleton pregnancies (adjusted odds ratio [OR] 4.2, 95% CI 3.1-5.8), both antepartum and intrapartum or postpartum, and regardless of the category of causal condition (severe hemorrhage, severe hypertensive complications, or other conditions). The association was also found for the most severe near-miss cases (adjusted OR 5.1, 95% CI 3.5-7.3). In path analysis, cesarean delivery mediated 20.6% (95% CI 12.9-28.2) of the total risk of intrapartum or postpartum severe acute maternal morbidity associated with twin pregnancy.CONCLUSION: Compared with women with singleton pregnancies, women with twin pregnancies have

esarean delivery is a useful intervention for mothers and newborns in many situations. Nonetheless, its rates have soared over the past 20 years in most developed countries, where more than 1 out of 5 women deliver by cesarean. 1 The range of indications for cesarean delivery appears to have broadened considerably, with more cesarean deliveries likely to be performed for questionable medical indications. 2-7 This increase requires evaluation of its potential adverse consequences on maternal and neonatal health. The long-term obstetric risks associated with the presence of a scarred uterus in future pregnancies are well recognized, primarily uterine rupture and abnormal placentation. 8-13 Conversely, conclusions about the comparative short-term maternal risks of cesarean and vaginal delivery remain unclear. A randomized controlled trial among women with no medical indication for cesarean delivery is, at best, ethically questionable. Observational studies can provide relevant information to address this, but their conclusions are likely to be limited owing to confounding by indication. That is, the fact that maternal morbidity may be a result of the condition indicating or justifying the cesarean delivery rather than to the surgical procedure itself can produce an apparent association between cesarean delivery and maternal morbidity. Earlier studies of the association between maternal mortality and mode of delivery have shown a higher risk of maternal mortality associated with cesarean versus vaginal deliveries. 14,15 These studies, however, were limited by their retrospective design, the rarity of maternal deaths and insufficient consideration of this confounding by indication. Over the past 10 years, numerous observational studies have reported discordant results about the association between cesarean and severe maternal morbidity, and their conclusions too are limited by several methodological flaws: insufficient control for confounding by indication, inappropriate definition of severe acute maternal morbidity, retrospective designs limiting quality and availability RESEARCH HEALTH SERVICES CPD Risk of severe maternal morbidity associated with cesarean delivery and the role of maternal age: a population-based propensity score analysis

The hypervirulent group B Streptococcus clone CC17 accounts for the majority of infant late-onset disease (LOD). We provide evidence that the high incidence of CC17 in LOD is likely due to an enhanced post-delivery mother-to-infant transmission.

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Background Maternal obesity is increasing. There is growing evidence of its effect on severe maternal morbidity. We assessed prepregnancy obesity as an independent risk factor for severe maternal morbidity by timing and cause. Methods We designed a case‐control analysis within the EPIMOMS prospective population‐based study conducted in six French regions in 2012‐2013 (182 309 women who delivered at ≥22 weeks). Cases were all women who experienced severe maternal morbidity during pregnancy to 42 days postpartum as per a multicriteria definition derived by national expert consensus (n = 2540, severe maternal morbidity prevalence 1.4%). Controls were randomly selected from the same health centres (n = 3651). The association between obesity and severe maternal morbidity was assessed from fitting multivariable logistic regression models: overall, by timing (antepartum and intrapartum/ postpartum), and by cause. Results Prepregnancy obesity was associated with overall severe maternal morbidity (adjusted odds ratio [OR] 1.34, 95% confidence interval [CI] 1.14, 1.59) and antepartum severe maternal morbidity (OR 2.07, 95% CI 1.61, 2.65), but not with intra/postpartum severe maternal morbidity (OR 1.15, 95% CI 0.96, 1.38). Among antepartum severe maternal morbidity, severe hypertensive disorders were most strongly associated with obesity (OR 2.50, 95% CI 1.85, 3.40) but the risk of antepartum severe maternal morbidity due to other causes was also increased among obese women (OR 1.64, 95% CI 1.13, 2.37). Obesity was not associated with severe postpartum haemorrhage (OR 1.12, 95% CI 0.92, 1.37). Conclusion Obesity is associated with an increased risk of antepartum, but not intra/ postpartum, severe maternal morbidity.

Objective To describe and compare the characteristics of women with placenta accreta spectrum (PAS) and their pregnancy outcomes according to the presence of placenta praevia and a prior caesarean section. Design Prospective population‐based study. Setting All 176 maternity hospitals of eight French regions. Population Two hundred and forty‐nine women with PAS, from a source population of 520 114 deliveries. Methods Women with PAS were classified into two risk‐profile groups, with or without the high‐risk combination of placenta praevia (or an anterior low‐lying placenta) and at least one prior caesarean. These two groups were described and compared. Main outcome measures Population‐based incidence of PAS, characteristics of women, pregnancies, deliveries and pregnancy outcomes. Results The PAS population‐based incidence was 4.8/10 000 (95% CI 4.2–5.4/10 000). After exclusion of women lost to follow up from the analysis, the group with placenta praevia and a prior caesarean included 115 (48%) women and the group without this combination included 127 (52%). In the group with both factors, PAS was more often suspected antenatally (77% versus 17%; P < 0.001) and more often percreta (38% versus 5%; P < 0.001). This group also had more hysterectomies (53% versus 21%, P < 0.001) and higher rates of blood product transfusions, maternal complications, preterm births and neonatal intensive care unit admissions. Sensitivity analysis showed similar results after exclusion of women who delivered vaginally. Conclusion More than half the cases of PAS occurred in women without the combination of placenta praevia and a prior caesarean delivery, and these women had better maternal and neonatal outcomes. We cannot completely rule out that some of the women who delivered vaginally had placental retention rather than PAS; however, we found similar results among women who delivered by caesarean. Tweetable abstract Half the women with PAS do not have both placenta praevia and a prior caesarean delivery, and they have better maternal outcomes.

(Abstracted from N Engl J Med 2018;379:731–742) The use of tranexamic acid (TXA) reduces mortality in the setting of postpartum hemorrhage (PPH). This study investigated whether the prophylactic administration of TXA in addition to prophylactic oxytocin in women with vaginal delivery would decrease the incidence of PPH.