Mitral valve prolapse: arrhythmic risk during pregnancy and postpartum.

BACKGROUND AND AIMS: Arrhythmic mitral valve prolapse (AMVP) is linked to life-threatening ventricular arrhythmias (VAs), and young women are considered at high risk. Cases of AMVP in women with malignant VA during pregnancy have emerged, but the arrhythmic risk during pregnancy is unknown. The authors aimed to describe features of women with high-risk AMVP who developed malignant VA during the perinatal period and to assess if pregnancy and the postpartum period were associated with a higher risk of malignant VA. METHODS: This retrospective international multi-centre case series included high-risk women with AMVP who experienced malignant VA and at least one pregnancy. Malignant VA included ventricular fibrillation, sustained ventricular tachycardia, or appropriate shock from an implantable cardioverter defibrillator. The authors compared the incidence of malignant VA in non-pregnant periods and perinatal period; the latter defined as occurring during pregnancy and within 6 months after delivery. RESULTS: The authors included 18 women with AMVP from 11 centres. During 7.5 (interquartile range 5.8-16.6) years of follow-up, 37 malignant VAs occurred, of which 18 were pregnancy related occurring in 13 (72%) unique patients. Pregnancy and 6 months after delivery showed increased incidence rate of malignant VA compared to the non-pregnancy period (univariate incidence rate ratio 2.66, 95% confidence interval 1.23-5.76). CONCLUSIONS: The perinatal period could impose increased risk of malignant VA in women with high-risk AMVP. The data may provide general guidance for pre-conception counselling and for nuanced shared decision-making between patients and clinicians.

Amniotic fluid embolism rescued by venoarterial extracorporeal membrane oxygenation.

BACKGROUND: Amniotic fluid embolism (AFE) is a rare but often catastrophic complication of pregnancy that leads to cardiopulmonary dysfunction and severe disseminated intravascular coagulopathy (DIC). Although few case reports have reported successful use of venoarterial extracorporeal membrane oxygenation (VA-ECMO) with AFE, concerns can be raised about the increased bleeding risks with that device. METHODS: This study included patients with AFE rescued by VA-ECMO hospitalized in two high ECMO volume centers between August 2008 and February 2021. Clinical characteristics, critical care management, in-intensive care unit (ICU) complications, and hospital outcomes were collected. ICU survivors were assessed for health-related quality of life (HRQL) in May 2021. RESULTS: During that 13-year study period, VA-ECMO was initiated in 54 parturient women in two high ECMO volume centers. Among that population, 10 patients with AFE [median (range) age 33 (24-40), SAPS II at 69 (56-81)] who fulfilled our diagnosis criteria were treated with VA-ECMO. Pregnancy evolved for 36 (30-41) weeks. Seven patients had a cardiac arrest before ECMO and two were cannulated under cardiopulmonary resuscitation. Pre-ECMO hemodynamic was severely impaired with an inotrope score at 370 (55-1530) µg/kg/min, a severe left ventricular ejection fraction measured at 14 (0-40)%, and lactate at 12 (2-30) mmol/L. 70% of these patients were alive at hospital discharge despite an extreme pre-ECMO severity and massive blood product transfusion. However, HRQL was lower than age-matched controls and still profoundly impaired in the role-physical, bodily pain, and general health components after a median of 44 months follow-up. CONCLUSION: In this rare per-delivery complication, our results support the use of VA-ECMO despite intense DIC and ongoing bleeding. Future studies should focus on customized, patient-centered, rehabilitation programs that could lead to improved HRQL in this population.

Delivery decision in pregnant women rescued by ECMO for severe ARDS: a retrospective multicenter cohort study.

BACKGROUND: Although rarely addressed in the literature, a key question in the care of critically pregnant women with severe acute respiratory distress syndrome (ARDS), especially at the time of extracorporeal membrane oxygenation (ECMO) decision, is whether delivery might substantially improve the mother's and child's conditions. This multicenter, retrospective cohort aims to report maternal and fetal short- and long-term outcomes of pregnant women with ECMO-rescued severe ARDS according to the timing of the delivery decision taken before or after ECMO cannulation. METHODS: We included critically ill women with ongoing pregnancy or within 15 days after a maternal/child-rescue-aimed delivery supported by ECMO for a severe ARDS between October 2009 and August 2021 in four ECMO centers. Clinical characteristics, critical care management, complications, and hospital discharge status for both mothers and children were collected. Long-term outcomes and premature birth complications were assessed. RESULTS: Among 563 women on venovenous ECMO during the study period, 11 were cannulated during an ongoing pregnancy at a median (range) of 25 (21-29) gestational weeks, and 13 after an emergency delivery performed at 32 (17-39) weeks of gestation. Pre-ECMO PaO2/FiO2 ratio was 57 (26-98) and did not differ between the two groups. Patients on ECMO after delivery reported more major bleeding (46 vs. 18%, p = 0.05) than those with ongoing pregnancy. Overall, the maternal hospital survival was 88%, which was not different between the two groups. Four (36%) of pregnant women had a spontaneous expulsion on ECMO, and fetal survival was higher when ECMO was set after delivery (92% vs. 55%, p = 0.03). Among newborns alive, no severe preterm morbidity or long-term sequelae were reported. CONCLUSION: Continuation of the pregnancy on ECMO support carries a significant risk of fetal death while improving prematurity-related morbidity in alive newborns with no difference in maternal outcomes. Decisions regarding timing, place, and mode of delivery should be taken and regularly (re)assess by a multidisciplinary team in experienced ECMO centers.

A Novel Partogram for Stages 1 and 2 of Labor Based on Fetal Head Station Measured by Ultrasound: A Prospective Multicenter Cohort Study.

OBJECTIVE: This study was aimed to describe continuous labor curves, including second stage, based on fetal head station. STUDY DESIGN: We performed a prospective multicenter cohort study. The inclusion criteria were women with singleton uncomplicated cephalic term pregnancies in labor, who delivered vaginally. We used a device that combines ultrasound imaging with position-tracking technology to monitor the head station noninvasively throughout labor. We collected data on demographics, labor parameters, and delivery and neonatal outcomes. RESULTS: A total of 613 women delivered vaginally, 327 (53.3%) were nulliparous, while 286 (46.7%) were multiparous. Time to delivery (TTD) diminished progressively with descent of the fetal head. When the head is engaged, the labor curve of multiparous women demonstrated a more prominent downward shift in curve as compared with nulliparous women. When comparing multipara and nullipara at engagement level, the median TTD was 1 and 1.62 hours, respectively. In 95% of women with unengaged head during the second stage, TTD of nulliparous and multiparous women were less than 3.8 and 3 hours, respectively. CONCLUSION: While current labor curves end at full dilatation, the described curves were developed throughout stages 1 and 2 of labor. The TTD, according to the station curves, shows an acceleration of labor, once passed the engagement level, especially in multiparous women.

European guidelines on perioperative venous thromboembolism prophylaxis: Surgery during pregnancy and the immediate postpartum period.

: Thromboembolic events in the pregnant and postpartum patient remain rare but potentially fatal complications. The aim of this section was to analyse the few prospective studies addressing the issue of thromboprophylaxis following a surgical procedure during and immediately after pregnancy, as well as national guidelines, and to propose European guidelines on this specific condition. Thromboprophylaxis is broadly recommended due to the combined risks of surgery and pregnancy or the postpartum period, regardless of the mode of delivery. We recommend prophylactic thromboprophylaxis following surgery during pregnancy or the postpartum period when they imply, as a consequence, bed rest, until full mobility is recovered (Grade 1C). Similarly, thromboprophylaxis should be used in cases of perioperative infection during pregnancy or the postpartum period. Concerning thromboprophylaxis following a caesarean section, it seems avoidable only in elective procedures in low-risk patients, after a normal pregnancy, and with an early rehabilitation protocol. The duration of thromboprophylaxis following caesarean section should be at least 6 weeks for high-risk patients, and at least 7 days for the other patients requiring anticoagulation (Grade 1C).

Gestational diabetes and adverse perinatal outcomes from 716,152 births in France in 2012.

AIMS/HYPOTHESIS: The aim of this study was to assess the risk of adverse perinatal outcomes in gestational diabetes mellitus (GDM) in a large national cohort. METHODS: All deliveries taking place after 22 weeks in France in 2012 were included by extracting data from the hospital discharge database and the national health insurance system. The diabetic status of mothers was determined by the use of glucose-lowering agents and by hospital diagnosis. Outcomes were analysed according to the type of diabetes and, in the GDM group, whether or not diabetes was insulin-treated. RESULTS: The cohort of 796,346 deliveries involved 57,629 (7.24%) mothers with GDM. Mother-infant linkage was obtained for 705,198 deliveries. The risks of adverse outcomes were much lower with GDM than with pregestational diabetes. After limiting the analysis to deliveries after 28 weeks to reduce immortal time bias, the risks of preterm birth (OR 1.3 [95% CI 1.3, 1.4]), Caesarean section (OR 1.4 [95% CI 1.4, 1.4]), pre-eclampsia/eclampsia (OR 1.7 [95% CI 1.6, 1.7]), macrosomia (OR 1.8 [95% CI 1.7, 1.8]), respiratory distress (OR 1.1 [95% CI 1.0, 1.3]), birth trauma (OR 1.3 [95% CI 1.1, 1.5]) and cardiac malformations (OR 1.3 [95% CI 1.1, 1.4]) were increased in women with GDM compared with the non-diabetic population. Higher risks were observed in women with insulin-treated GDM than those with diet-treated GDM. After limiting the analysis to term deliveries, an increased risk of perinatal mortality was observed. After excluding women suspected to have undiagnosed pregestational diabetes, the risk remained moderately increased only for those with diet-treated GDM (OR 1.3 [95% CI 1.0, 1.6]). CONCLUSIONS/INTERPRETATION: GDM is associated with a moderately increased risk of adverse perinatal outcomes, which is higher in insulin-treated GDM than in non-insulin-treated GDM for most outcomes.

Evolution of cesarean categories in a modified Robson classification in a single center from 2002 to 2012 due to high rate of maternal pathology.

AIM: To study the evolution in cesarean section (CS) categories in a single center from 2002 to 2012. METHODS: We performed a retrospective study on all live births from 2002, 2007, and 2012 using a modified Robson classification accounting for cervical ripening in the induction groups, post-term pregnancies, and the number of uterine scars. RESULTS: We recorded 2162, 2105 and 2380 deliveries with caesarean delivery rates of 23.2%, 24.9%, and 30.4% in 2002, 2007, and 2012 respectively. Nulliparous women in spontaneous labor (group 1) decreased from 36.3% to 27.4% of the total population, but CS rates in this group increased from 14.1% to 19.5% (P < 0.05). Labor induction and CS before labor in nulliparous women category (group 2) increased from 6.7% to 14.2% but with stable CS rates. Induction of labor and cervical ripening in this group increased from 91 and nine in 2002 to 119 and 240 in 2012, respectively. In the same period, maternal pathology increased from 11% to 33%. Scarred uterus remained the major source of CS (almost 30% of all CS in 2012). CONCLUSION: CS rates increased throughout the studied period, associated with an increase in rates of maternal pathology, induction by cervical ripening, and scarred uterus.

A proposal for the use of uniform diagnostic criteria for gestational diabetes in Europe: an opinion paper by the European Board & College of Obstetrics and Gynaecology (EBCOG).

Screening and diagnostic criteria for gestational diabetes (GDM) are inconsistent across Europe, and the development of a uniform GDM screening strategy is necessary. Such a strategy would create opportunities for more women to receive timely treatment for GDM. Developing a consensus on screening for GDM in Europe is challenging, as populations are diverse and healthcare delivery systems also differ. The European Board & College of Obstetrics and Gynaecology (EBCOG) has responded to this challenge by appointing a steering committee, including members of the EBCOG and the Diabetic Pregnancy Study Group (DPSG) associated with the EASD, to develop a proposal for the use of uniform diagnostic criteria for GDM in Europe. A proposal has been developed and has now been approved by the Council of the EBCOG. The current proposal is to screen for overt diabetes at the first prenatal contact using cut-off values for diabetes outside pregnancy, with particular efforts made to screen high-risk groups. When screening for GDM is performed at 24 weeks' gestation or later, the proposal is now to use the 75 g OGTT with the new WHO diagnostic criteria for GDM. However, more research is necessary to evaluate the best GDM screening strategy for different populations in Europe. Therefore, no clear recommendation has been made on whether a universal one-step, two-step or a risk-factor-based screening approach should be used. The use of the same WHO diagnostic GDM criteria across Europe will be an important step towards uniformity.

Humanitarian obstetric care for refugees of the Syrian war. The first 6 months of experience of Gynécologie Sans Frontières in Zaatari Refugee Camp (Jordan).

OBJECTIVE: To report the first 6 months of experience of a nongovernmental-organization-managed obstetric care unit in a war refugee camp, with problems encountered and solutions implemented. DESIGN: Prospective observational study of the maternity activity of Gynécologie Sans Frontières (GSF). SETTING: GSF's maternity unit, in Zaatari camp (Jordan). POPULATION: All pregnant women among Syrian refugees who came to the unit for delivery. METHODS: The GSF's maternity unit is a light structure built with three tents, permitting low-risk pregnancy care and childbirth. Emergency cesarean deliveries were performed in the Moroccan army field hospital. High-risk pregnancies were transferred to Al Mafraq or Amman Hospital (Jordan) after assessment. MAIN OUTCOME MEASURES: Delivery characteristics, indications for referral. RESULTS: From September 2012 to February 2013, 371 women attended the unit and 299 delivered in it. Delivery rates increased from 5/month to 112/month over the period. Mean gestational age at birth was 39(+3) gestational weeks (SD = 1.9). Median birthweight was 3100 g (25-75% interquartile range 2840-3430 g). Spontaneous vaginal deliveries were dominant and the major maternal complication was postpartum hemorrhage (n = 13). Eighty-two women were referred to Al Mafraq or Amman hospitals, mainly for preterm labor (32%) and congenital malformations (11%). We managed one case of stillbirth. Maternal mortality did not occur. CONCLUSIONS: Despite the difficulties of war, high-risk pregnant women were properly identified, permitting referrals when required. Cooperation with other nongovernmental organizations, including the United Nations High Commissioner for Refugees, was essential for the management of situations at risk of complications and to contain perinatal and maternal mortality.

Behçet's disease and pregnancy.

OBJECTIVE: To describe the interplay between Behçet's disease (BD) and pregnancy. METHODS: This retrospective study included 76 pregnancies in 46 patients fulfilling the international criteria for BD. The median age of the patients at the time of entry into the study was 28.4 years (interquartile range 22.8-30.9 years). Patients were used as their own historical controls to assess the incidence of BD flares during pregnancy and before or after pregnancy. Factors associated with the occurrence of complications during pregnancy were assessed. RESULTS: Among the 76 pregnancies with BD analyzed, 27 (35.5%) were associated with worsening of the symptoms of BD flare; oral and genital ulcerations (78.4% and 67.6%, respectively) as well as ocular complications (32.4%) were the most frequent. The mean ± SD annual rates of BD flares were 0.49 ± 0.72 during pregnancy and 1.46 ± 2.42 during the nonobstetric period (P = 0.018). The proportion of BD flares tended to be lower in patients treated with colchicine (27.9% versus 45.4% of patients not treated with colchicine; P = 0.11). The overall rate of complications during pregnancy was 15.8%. The complications included miscarriage (5 patients), cesarean delivery (3 patients), medical termination of pregnancy (2 patients), hemolysis, elevated liver enzymes, and low platelets syndrome (1 patient), and immune thrombocytopenia (1 patient). There was a statistically significant association between a history of deep vein thrombosis in BD and the risk of obstetric complications (odds ratio 7.25, 95% confidence interval 1.21-43.46, P = 0.029). Neither gestational age at delivery nor neonatal outcome was influenced by BD. CONCLUSION: The disease course in BD seems to improve during pregnancy, mostly in patients who are treated with colchicine. Pregnancy in patients with BD appears not to be associated with an increased rate of pregnancy-related complications.

Pregnancy Outcomes After Bariatric Surgery: Importance of Maternal Ferritin on Birth Weight.

PURPOSE: The risks carried by pregnancy after bariatric surgery (BS) include small-for-gestational age (SGA) newborn and prematurity. However, the underlying mechanisms are not yet fully understood in pregnant women after BS. MATERIAL AND METHODS: This single-center retrospective observational cohort study includes all women with a first and single pregnancy after BS who completed at least one clinical and biological nutritional assessment during pregnancy between 2010 and 2016. The quarterly biological assessment comprised blood count, ferritin, calcium, 25OH vitamin D, parathyroid hormone, fasting glucose, albumin, prealbumin, vitamin A, vitamin B12, folic acid, and zinc. RESULTS: Among 120 pregnancies analysed, two-thirds underwent gastric bypass (Roux-en-Y and one-anastomosis) and one-third a restrictive procedure (adjustable gastric band or sleeve gastrectomy). The median [Q1-Q3] preoperative BMI was 43.8 [41.1-47.7] kg/m2 and the mean age at pregnancy was 32.6 ± 5.3 years. Weight loss and time from surgery to pregnancy were 35.1 ± 15.4 kg and 2.9 [1.3-4.5] years, respectively. Ten women (8%) gave birth prematurely, and 22 newborns (19%) were SGA. Univariate analysis shows that ferritin was significantly higher in mothers with SGA than in those without SGA (35.5 [22.3-69.5] vs. 15 [10-32] ng/ml) at third trimester of pregnancy. Women who received pre-pregnancy nutritional assessment seemed less likely to give birth to a SGA newborn (32% vs. 54%, p = 0.07). CONCLUSION: Iron supplementation should be carefully prescribed and closely monitored during pregnancy in women who have undergone BS.

Pregnancy and cardiac maternal outcomes in women with inherited cardiomyopathy: interest of the CARPREG II risk score.

AIMS: Inherited cardiomyopathies are relatively rare but carry a high risk of cardiac maternal morbidity and mortality during pregnancy and postpartum. However, data for risk stratification are scarce. The new CARPREG II score improves prediction of prognosis in pregnancies associated with heart disease, though its role in inherited cardiomyopathies is unclear. We aim to describe characteristics and cardiac maternal outcomes in patients with inherited cardiomyopathy during pregnancy, and to evaluate the interest of the CARPREG II risk score in this population. METHODS AND RESULTS: In this retrospective single-centre study, 90 consecutive pregnancies in 74 patients were included (mean age 32 ± 5 years), including 28 cases of dilated cardiomyopathy (DCM), 46 of hypertrophic cardiomyopathy, 11 of arrhythmogenic right ventricular cardiomyopathy and 5 of left ventricular noncompaction, excluding peripartum cardiomyopathy. The discriminatory power of several risk scores was assessed by the area under the receiver-operating characteristic curve (AUC). Median CARPREG II score was 2 [0;3] and was higher in the DCM subgroup. A severe cardiac maternal complication was observed in 18 (20%) pregnancies, mainly driven by arrhythmia and heart failure (each event in 10 pregnancies), with 3 cardiovascular deaths. Forty-three pregnancies (48%) presented foetal/neonatal complications (18 premature delivery, 3 foetal/neonatal death). CARPREG II was significantly associated with cardiac maternal complications (P < 0.05 for all) and showed a higher AUC (0.782) than CARPREG (0.755), mWHO (0.697) and ZAHARA (0.604). CONCLUSIONS: Pregnancy in women with inherited cardiomyopathy carries a high risk of maternal cardiovascular complications. CARPREG II is the most efficient predictor of cardiovascular complications in this population.

Catastrophic antiphospholipid syndrome and pregnancy: an experience of 13 cases.

OBJECTIVE: Catastrophic antiphospholipid syndrome (CAPS) is a life-threatening disease caused by the onset of rapidly progressive and widespread small-vessel thromboses in the presence of aPLs. The aim of this study was to examine pregnancy-related CAPS. METHODS: Retrospective series of 13 patients with pregnancy-related CAPS with special focus on the follow-up. RESULTS; Eleven patients had known APS and had been treated with low-molecular-weight heparin (n = 10), aspirin (n = 8), oral anticoagulants (n = 1), HCQ (n = 3) and/or steroids (n = 1) during pregnancy. The most frequent manifestations of CAPS were cutaneous (n = 11), hepatic (n = 11), renal (n = 10), cardiac (n = 8) and neurological (n = 5). CAPS usually followed haemolysis, elevated liver enzymes and low platelet count (HELLP) syndrome (n = 12), which was associated with pre-eclampsia (n = 6) or with eclampsia (n = 3). No maternal death was observed. The perinatal mortality of 54% was related to prematurity with a mean gestational age of 26.6 weeks at onset of CAPS or HELLP syndrome. During a mean follow-up of 4.8 years (range 2-8 years), seven new pregnancies occurred in five patients and led to one miscarriage, four successful pregnancies and two HELLP syndrome with pre-eclampsia or eclampsia that occurred at 28 weeks gestation in both cases despite optimal treatment. No relapse of CAPS was observed. Two mothers suddenly died 2.5 and 6 years after CAPS. CONCLUSION: The occurrence of HELLP syndrome in a patient with APS should raise the suspicion of CAPS in the following days, and anticoagulation should be maintained post-partum or post-abortum. Subsequent pregnancies are at very high risk.

Pregnant women with mild COVID-19 followed in community setting by telemedicine, and factors associated with unfavorable outcome.

OBJECTIVES: Few is known on pregnant women with mild COVID-19 managed in a community setting with a telemedicine solution, including their outcomes. The objective of this study is to evaluate the adverse fetal outcomes and hospitalization rates of pregnant COVID-19 outpatients who were monitored with the Covidom© telemedicine solution. METHODS: A nested study was conducted on pregnant outpatients with confirmed COVID-19, who were managed with Covidom© between March and November 2020. The patients were required to complete a standard medical questionnaire on co-morbidities and symptoms at inclusion, and were then monitored daily for 30 days after symptom onset. Adverse fetal outcome was defined as a composite of preterm birth, low birthweight, or stillbirth, and was collected retrospectively through phone contact with a standardized questionnaire. RESULTS: The study included 714 pregnant women, with a median age of 32.0 [29.0-35.0] and a median BMI of 23.8 [21.3-27.0]. The main comorbidities observed were smoking (53%), hypertension (19%). The most common symptoms were asthenia (45.6%), cough (40.3%) and headache (25.7%), as well as anosmia (28.4%) and agueusia (32.3%). Adverse fetal outcomes occurred in 64 (9%) cases, including 38 (5%) preterm births, 33 (5%) low birthweights, and 6 (1%) stillbirths. Hospitalization occurred in 102 (14%) cases and was associated with adverse fetal outcomes (OR 2.4, 95% CI 1.3-4.4). CONCLUSIONS: Our study suggests that adverse fetal outcomes are rare in pregnant women with mild COVID-19 who are monitored at home with telemedicine. However, hospitalization for COVID-19 and pregnancy-induced hypertension are associated with a higher risk of adverse fetal outcome.

Risk-Benefit Balance Associated With Obstetric, Neonatal, and Child Outcomes After Metabolic and Bariatric Surgery.

Importance: Metabolic and bariatric surgery (MBS) is the most efficient therapeutic option for severe obesity. Most patients who undergo MBS are women of childbearing age. Data in the scientific literature are generally of a low quality due to a lack of well-controlled prospective trials regarding obstetric, neonatal, and child outcomes. Objective: To assess the risk-benefit balance associated with MBS around obstetric, neonatal, and child outcomes. Design, Setting, and Participants: The study included 53 813 women on the French nationwide database who underwent an MBS procedure and delivered a child between January 2012 and December 2018. Each women was their own control by comparing pregnancies before and after MBS. Exposures: The women included were exposed to either gastric bypass or sleeve gastrectomy. Main Outcomes and Measures: The study team first compared prematurity and birth weights in neonates born before and after maternal MBS with each other. Then they compared the frequencies of all pregnancy and child diagnoses in the first 2 years of life before and after maternal MBS with each other. Results: A total of 53 813 women (median [IQR] age at surgery, 30 [26-35] years) were included, among 3686 women who had 1 pregnancy both before and after MBS. The study team found a significant increase in the small-for-gestational-age neonate rate after MBS (+4.4%) and a significant decrease in the large-for-gestational-age neonate rate (-12.6%). The study team highlighted that compared with pre-MBS births, after MBS births had fewer occurrences of gestational hypertension (odds ratio [OR], 0.16; 95% CI, 0.10-0.23) and gestational diabetes for the mother (OR, 0.39; 95% CI, 0.34-0.45), as well as fewer birth injuries to the skeleton (OR, 0.27; 95% CI, 0.11-0.60), febrile convulsions (OR, 0.39; 95% CI, 0.21-0.67), viral intestinal infections (OR, 0.56; 95% CI, 0.43-0.71), or carbohydrate metabolism disorders in newborns (OR, 0.54; 95% CI 0.46-0.63), but an elevated respiratory failure rate (OR, 2.42; 95% CI, 1.76-3.36) associated with bronchiolitis. Conclusions and Relevance: The risk-benefit balance associated with MBS is highly favorable for pregnancies and newborns but may cause an increased risk of respiratory failure associated with bronchiolitis. Further studies are needed to better assess the middle- and long-term benefits and risks associated with MBS.