Pregnancy Outcomes after Uterine Preservation Surgery for Placenta Accreta Spectrum: A Retrospective Cohort Study.

OBJECTIVE: This study aimed to investigate maternal and neonatal outcomes in subsequent pregnancies of women with a history of placenta accreta spectrum (PAS) compared with women without history of PAS. STUDY DESIGN: A retrospective cohort study conducted at a single tertiary center between March 2011 and January 2022. We compared women with a history of PAS who had uterine preservation surgery and a subsequent pregnancy, to a control group matched in a 1:5 ratio. The primary outcome was the occurrence of a composite adverse outcome (CAO) including any of the following: uterine dehiscence, uterine rupture, blood transfusion, hysterectomy, neonatal intensive care unit admission, and neonatal mechanical ventilation. Multivariable logistic regression was performed to evaluate associations with the CAO. RESULTS: During the study period, 287 (1.1%) women were diagnosed with PAS and delivered after 25 weeks of gestation. Of these, 32 (11.1%) women had a subsequent pregnancy that reached viability. These 32 women were matched to 139 controls. There were no significant differences in the baseline characteristics between the study and control groups. Compared with controls, the proportion of CAO was significantly higher in women with previous PAS pregnancy (40.6 vs. 19.4%, p = 0.019). In a multivariable logistic regression analysis, previous PAS (adjusted odds ratio [aOR] = 3.31, 95% confidence interval [CI] = 1.09-10.02, p = 0.034) and earlier gestational age at delivery (aOR = 3.53, 95% CI = 2.27-5.49, p < 0.001) were independently associated with CAOs. CONCLUSION: A history of PAS in a previous pregnancy is associated with increased risk of CAOs in subsequent pregnancies. KEY POINTS: · The uterine-preserving approach for PAS delivery is gaining more attention and popularity in recent years.. · Women with a previous pregnancy with PAS had higher rates of CAOs in subsequent pregnancies.. · Previous PAS pregnancy is an independent factor associated with adverse outcomes..

Accidental uterine extensions in cesarean deliveries - outcome of subsequent pregnancy.

OBJECTIVES: To explore the obstetric, maternal and neonatal outcome in the subsequent pregnancy after a pregnancy with an accidental uterine extension (AUE) during cesarean delivery (CD), as well as the relationship between the different types of AUE (inferior, lateral and superior). METHODS: A retrospective cohort study of all CD with AUE in a tertiary medical center between 01/2011-01/2022. Women with a prior CD with AUE were compared to a 1:3 ratio matched control group of women with a prior CD without AUE. All AUE were defined in their direction, size and mode of suturing. CD with deliberate uterine extensions were excluded. We evaluated obstetric, maternal and neonatal outcomes in the subsequent pregnancy after a pregnancy with AUE during CD. RESULTS: Comparing women with a prior CD with AUE (n=177) to the matched control group of women with a prior CD without AUE (n=528), we found no significant differences in proportions of uterine rupture or any other major complication or adverse outcome between the groups. There were no significant differences in the outcomes of the subsequent pregnancy in relation to the characteristics of the AUE (direction, size and mode of suturing). CONCLUSIONS: Subsequent pregnancies after AUE are not associated with higher maternal or neonatal adverse outcomes including higher proportions of uterine rupture compared to pregnancies without previous AUE. Different characteristics of the AUE do not impact the outcome.

24-Hour Compared With 12-Hour Mifepristone-Misoprostol Interval for Second-Trimester Abortion: A Randomized Controlled Trial.

OBJECTIVE: To compare 24-hour and 12-hour mifepristone-to-misoprostol intervals for second-trimester medication abortion. METHODS: We conducted a prospective randomized controlled trial. Participants were allocated to receive mifepristone either 24 hours or 12 hours before misoprostol administration. The primary outcome was the time from the first misoprostol administration to abortion (induction time). Secondary outcomes included the time from mifepristone to abortion (total abortion time); fetal expulsion percentages at 12, 24, and 48 hours after the first misoprostol dose; side effects proportion; and pain and satisfaction scores. A sample size of 40 per group (N=80) was planned to compare the 24- and 12-hour regimens. RESULTS: Eighty patients were enrolled between July 2020 and June 2023, with 40 patients per group. Baseline characteristics were comparable between groups. Median induction time was 9.5 hours (95% CI, 10.3-17.8 hours) and 12.5 hours (95% CI, 13.5-20.2 hours) in the 24- and 12-hour interval arms, respectively ( P =.028). Median total abortion time was 33.0 hours (95% CI, 34.2-41.9 hours) and 24.5 hours (95% CI, 25.7-32.4 hours) in the 24- and 12-hour interval groups, respectively ( P <.001). At 12 hours from misoprostol administration, 25 patients (62.5%) in the 24-hour arm and 18 patients (45.0%) in the 12-hour arm completed abortion ( P =.178). At 24 hours from misoprostol administration, 36 patients (90.0%) in the 24-hour arm and 30 patients (75.0%) in the 12-hour arm had complete abortion ( P =.139). The need for additional medication or surgical treatment for uterine evacuation, pain scores, side effects, and satisfaction levels were not different between groups. CONCLUSION: A 24-hour mifepristone-to-misoprostol regimen for medication abortion in the second trimester provides a median 3-hour shorter induction time compared with the 12-hour interval. However, the median total abortion time was 8.5-hours longer in the 24-hour interval regimen. These findings can aid in shared decision making before medication abortion in the second trimester. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT04160221.

Obstetric and Early Neonatal Outcomes Following Second and Third COVID-19 Vaccination in Pregnancy.

BACKGROUND: Pregnant women are at higher risk for severe coronavirus disease 2019 (COVID-19). Since the release of the BNT162b2 messenger RNA vaccine (Pfizer/BioNTech), there has been accumulated data about the three vaccine doses. However, information regarding obstetric and neonatal outcomes of pregnant women vaccinated with the third (booster) vaccine is limited and primarily retrospective. OBJECTIVES: To evaluate the obstetric and early neonatal outcomes of pregnant women vaccinated during pregnancy with the COVID-19 booster vaccine compared to pregnant women vaccinated only by the first two doses. METHODS: We conducted a cross-sectional study of pregnant women who received the BNT162b2 vaccine during pregnancy. Obstetric and neonatal outcomes were compared between pregnant women who received only the first two doses of the vaccine to those who also received the booster dose. RESULTS: Overall, 139 pregnant women were vaccinated during pregnancy with the first two doses of the vaccine and 84 with the third dose. The third dose group received the vaccine earlier during their pregnancy compared to the two doses group (212 vs. 315 weeks, respectively, P < 0.001). No differences in obstetric and early neonatal outcomes between the groups were found except for lower rates of urgent cesarean delivery in the third dose group (adjusted odds ratio 0.21; 95% confidence interval 0.048-0.926, P = 0.039). CONCLUSIONS: Compared to the first two doses of the BNT162b2 vaccine given in pregnancy, the booster vaccination is safe and not associated with an increased rate of adverse obstetric and early neonatal outcomes.

Neonatal outcomes in pregnancies complicated by placenta accreta- a matched cohort study.

PURPOSE: Pregnancies complicated by placenta accreta spectrum (PAS) are associated with severe maternal morbidities. The aim of this study is to describe the neonatal outcomes in pregnancies complicated with PAS compared with pregnancies not complicated by PAS. METHODS: A retrospective cohort study conducted at a single tertiary center between 03/2011 and 01/2022, comparing women with PAS who underwent cesarean delivery (CD) to a matched control group of women without PAS who underwent CD. We evaluated the following adverse neonatal outcomes: umbilical artery pH < 7.0, umbilical artery base excess ≤ - 12, APGAR score < 7 at 5 min, neonatal intensive care unit (NICU) admission, mechanical ventilation, hypoxic ischemic encephalopathy, seizures and neonatal death. We also evaluated a composite adverse neonatal outcome, defined as the occurrence of at least one of the adverse neonatal outcomes described above. Multivariable regression analysis was used to determine which adverse neonatal outcome were independently associated with the presence of PAS. RESULTS: 265 women with PAS were included in the study group and were matched to 1382 controls. In the PAS group compared with controls, the rate of composite adverse neonatal outcomes was significantly higher (33.6% vs. 18.7%, respectively, p < 0.001). In a multivariable logistic regression analysis, Apgar score < 7 at 5 min, NICU admission and composite adverse neonatal outcome were independently associated with PAS. CONCLUSION: Neonates in PAS pregnancies had higher rates of adverse outcomes. Apgar score < 7 at 5 min, NICU admission and composite adverse neonatal outcome were independently associated with PAS.

Clinical implications of a cesarean scar pregnancy sonographic evaluation and reporting system.

OBJECTIVES: Recently, a new standardized sonographic evaluation system for cesarean scar pregnancies (CSP) was published. We aimed to evaluate the clinical outcomes of CSP cases according to the new sonographic evaluation and reporting system. STUDY DESIGN: A retrospective study conducted at a single tertiary center. All CSPs between 1/2011 and 4/2022 were included. Cases were evaluated by expert sonographers and classified into three categories: 1) CSP in which the largest part of the gestational sac (GS) protrudes towards the uterine cavity; 2) CSP in which the largest part of the GS is embedded in the myometrium but does not cross the serosal contour; and 3) CSP in which the GS is partially located beyond the outer contour of the cervix or uterus.Baseline characteristics, management and outcomes were compared between the three categories. RESULTS: Overall, 55 patients were diagnosed with CSP during the study period; 10 (18.1 %) type 1, 31 (56.3 %) type 2, and 14 (25.4 %) type 3. Baseline characteristics were similar among groups. Compared with type 2 and 3, patients diagnosed with CSP type 1 received less methotrexate treatment [83.9 % and 78.6 % vs. 40.0 %, respectively, p = 0.020]. The rates of need for invasive procedures, urgent procedures, major bleeding, length of hospitalization, and subsequent pregnancies were similar between groups. CONCLUSIONS: No clinically significant differences were found between groups divided by the new standardized sonographic evaluation and reporting system for CSP in pregnancy characteristics, management, and subsequent pregnancy outcomes. Further investigation is required to enable informed management of CSP based on the new sonographic reporting system.

Reconsidering the effectiveness of low-dose aspirin in prevention of pre-eclampsia among otherwise low risk twin gestations: A historical cohort study.

OBJECTIVE: To investigate the effectiveness of low-dose aspirin (LDA) in the prevention of pre-eclampsia (PE) among otherwise low-risk twin gestations. METHODS: A historical cohort study consisting of all pregnant individuals with dichorionic diamniotic (DCDA) twin pregnancy who delivered between 2014 and 2020. Patients treated with LDA were matched by a 1:4 ratio to individuals who were not treated with LDA by age, body mass index and parity. RESULTS: During the study period, 2271 individuals carrying DCDA pregnancies delivered at our center. Of these, 404 were excluded for one or more additional major risk factors. The remaining cohort consisted of 1867 individuals of whom 142 (7.6%) were treated with LDA and were compared with a 1:4 matched group of 568 individuals who were not treated. The rate of preterm PE did not differ significantly between the two groups (18 [12.7%] in the LDA group vs. 55 [9.7%] in the no-LDA group; P = 0.294, adjusted odds ratio 1.36, 95% confidence interval 0.77-2.40). There were no other significant between-group differences. CONCLUSIONS: Low-dose aspirin treatment in pregnant individuals with DCDA twin gestations without additional major risk factors was not associated with a reduction in the rate of preterm PE.

Transient osteoporosis of the hip in pregnancy - a case series.

OBJECTIVE: Transient Osteoporosis of the Hip is a self-limiting disorder of severe hip joint pain presenting in pregnancy or postpartum, of which magnetic resonance imaging (MRI) is the modality of choice for diagnosis. Clinical data regarding transient osteoporosis of the hip is limited, precluding evidence-based decision-making such as recommended mode of delivery. In this case-series retrospective study, we aim to describe the natural course of transient osteoporosis of the hip during pregnancy and the postpartum period including implications of the mode of delivery. METHODS: All women diagnosed with unilateral/bilateral transient osteoporosis of the hip by MRI during pregnancy or postpartum between 2010 and 2019 at a single tertiary medical center were retrospectively studied. All MRI scans were reviewed by an experienced radiologist at the same single tertiary medical center. Data obtained from patients' electronic medical records and telephone questionnaires included maternal baseline characteristics, obstetric history, and current pregnancy obstetric and clinical outcome characteristics. Outcomes of normal vaginal delivery (NVD) and cesarean delivery (CD) were compared and analyzed. RESULTS: Thirty-four women were diagnosed with unilateral or bilateral transient osteoporosis of the hip during pregnancy (17 women) and postpartum (17 women). The mean maternal age was 34.18 ± 4.75 years. A family history of osteoporosis was reported in a rate of 29.4%. The rate of smokers was 47.1%, 32.4% of pregnancies were conceived by in-vitro fertilization (IVF), pre-pregnancy and term body mass index (BMI) were 22.03 and 27.6, respectively. No significant differences were found between NVD and CD in all parameters evaluated. Of 15 women with a sequential pregnancy, two were diagnosed with transient osteoporosis of the hip (13.3%). CONCLUSION: Women diagnosed with transient osteoporosis of the hip had advanced maternal age, low BMI, family history of osteoporosis, prevalent smoking and IVF pregnancies. Transient osteoporosis of the hip was bilateral in 25% and presented postpartum in 50% of cases. There was no significant difference in maternal outcomes between NVD and CD. Higher awareness of this potential diagnosis during pregnancy and postpartum may improve patient management and outcomes.

Maternal and Neonatal Immune Responses Following COVID-19 Infection and Vaccinations in Pregnancy.

The objective of the study was to compare the maternal and neonatal humoral immune responses among different groups of women, namely those vaccinated by the BNT162b2 vaccine, not vaccinated, and COVID-19-recovered parturient women at the time of delivery. This is a prospective cohort study of pregnant women, divided into four groups: Group A "Recovered"-recovered and not vaccinated. Group B "Second Vaccination"-first and second doses only. Group C "Third Vaccination"-third dose. Group D "No Third Vaccination"-women eligible for the third dose of the vaccine but did not receive it. Maternal and umbilical cord blood were sampled and tested for SARS-CoV-2 IgG antibodies on admittance to labor and immediately postpartum, respectively. Maternal serum SARS-CoV-2 IgG levels were significantly higher among Group C compared to Group B (741.6 (514.5-1069) vs. 333.5 (327-340.2), respectively). Both groups had higher antibody levels compared to Groups A and D (113.5 (61.62-209.1) and 57.99 (32.93-102.1), respectively). Similarly, umbilical cord blood SARS-CoV-2 IgG levels were also highest among Group C compared to the other three groups (1269 (953.4-1690) vs. Group B, 322.6 (305.6-340.5), Group A, 109 (49.01-242.6), and Group D, 103.9 (48.59-222), respectively). In conclusion, pregnant women who were fully vaccinated with three dosages before delivery generated the highest levels of maternal and neonatal SARS-CoV-2 IgG antibodies.

Early Adverse Events and Immune Response Following Second and Third COVID-19 Vaccination in Pregnancy.

(1) Background: The adverse-effect profile and short-term obstetric and neonatal outcomes among pregnant women who were vaccinated with the BNT162b2 vaccine at any stage of pregnancy do not indicate any safety concerns. The vaccine is effective in generating a humoral immune response in pregnant women. (2) Objective: To determine the vaccine-induced immunity and adverse events associated with the third (booster) dose of the BNT162b2 vaccine compared to the first and second dose of the vaccine among pregnant women. (3) Study design: A prospective cohort study in a tertiary referral center comparing pregnant women who were vaccinated by the first and second dose of the BNT162b2 (Pfizer/BioNTech) vaccine to pregnant women vaccinated by a third (booster) dose, between January and November 2021. A digital questionnaire regarding adverse events was filled by both groups 2−4 weeks after vaccination. Blood samples were collected and tested for SARS-COV-2 IgG antibodies 28−32 days after the administration of the second or third BNT162b2 dose. (4) Results: Seventy-eight pregnant women who received the first and second doses of the vaccine were compared to eighty-four pregnant women who received the third dose of the vaccine. In terms of adverse events following vaccination, local rash/pain/swelling (93.6% vs. 72.6%, p < 0.001) was significantly less common after the third vaccination compared to after the second vaccination. Other adverse events, including early obstetric complications, did not differ between the two groups. SARS-CoV-2 IgG serum levels 28−32 days after the vaccination were significantly higher after the third vaccination compared to the second vaccination (1333.75 vs. 2177.93, respectively, p < 0.001). (5) Conclusion: This study confirms the safety regarding early adverse events and immunogenicity, and the lack of early obstetric complications of the BNT162b2 second- and third-dose vaccine in pregnant women. The third (booster) dose is effective in generating a stronger humoral immune response in pregnant women compared with the second dose.

A validated predictive model for adnexal torsion pre-operative diagnosis.

PURPOSE: To develop a simple predictive model for pre-operative diagnosis of adnexal torsion (AT). METHODS: A retrospective cohort study with a retrospective validation, including 669 separate episodes of women who underwent laparoscopy due to a suspected AT between January 2011 and June 2020. We compared the pre-operative characteristics between women with surgically confirmed AT and those without. RESULTS: The derivation cohort included 615 episodes of suspected AT. AT was surgically confirmed in 445 episodes (72%). The retrospectively collected validation cohort included 54 episodes, with 31 (57.4%) surgically confirmed AT. In a multivariate regression analysis, vomiting, neutrophils to lymphocytes ratio > 3.5 and sonographic finding of enlarged ovary were independently associated with AT [OR 95% CI 2.78 (1.21-6.36), 3.15 (1.42-6.97) and 2.80 (1.33-5.88), respectively]. In the derivation cohort, the PPV for AT diagnosis was 69.7%, 84.5% and 93.1% if 1, 2 and 3 risk factors were present, respectively. Retrospective validation analysis underlined a PPV of 67.6%, 82.6 and 66.6% for 1, 2 and 3 risk factors, respectively. CONCLUSION: We have developed and validated a simple predictive model for pre-operative diagnosis of AT, based on three parameters. Our model may assist clinicians while evaluating patients with suspected AT and improve pre-operative diagnosis.

Maternal-neonatal transfer of SARS-CoV-2 immunoglobulin G antibodies among parturient women treated with BNT162b2 messenger RNA vaccine during pregnancy.

BACKGROUND: The exclusion of pregnant women from initial COVID-19 messenger RNA vaccine trials raised hesitancy regarding the benefits of vaccination for pregnant women, hence little is known about vaccines' efficacy in this population. OBJECTIVE: To determine the maternal-neonatal transplacental transfer of SARS-CoV-2 antibodies among vaccinated parturient women. A control group of COVID-19-recovered patients was included to compare the immunoglobulin G levels between vaccinated and recovered patients. STUDY DESIGN: This is a prospective cohort study conducted in a single tertiary medical center in Israel between February and March 2021; parturient women vaccinated with the BNT162b2 messenger RNA vaccine during pregnancy were included and compared with COVID-19-recovered parturient women. SARS-CoV-2 immunoglobulin G antibodies were measured in maternal and cord sera, dried blood spot samples taken from newborns, and breast milk samples. The primary aim was to determine whether neonatal cord and dried blood spot samples were positive for SARS-CoV-2 antibodies and to evaluate the transfer ratio, defined as cord blood immunoglobulin G divided by maternal immunoglobulin G levels. RESULTS: The study included 64 vaccinated parturient women and 11 parturient women who had COVID-19 during pregnancy. All maternal blood sera samples and 98.3% of the cord blood sera samples were positive for SARS-Cov-2 immunoglobulin G with median concentrations of 26.1 (interquartile range, 22.0-39.7) and 20.2 (interquartile range, 12.7-29.0), respectively. Similarly, 96.4% of neonatal blood spot samples and all breast milk samples were positive for SARS-CoV-2 immunoglobulin G with median concentrations of 11.0 (interquartile range, 7.2-12.8) and 4.9 (interquartile range, 3.8-6.0), respectively. There was a significant positive correlation between maternal serum levels of SARS-CoV-2 immunoglobulin G and cord blood (r=0.483; P=.0001), neonatal blood spot (r=0.515; P=.004), and breast milk levels (r=0.396; P=.005) of SARS-CoV-2 immunoglobulin G. The median placental transfer ratio of SARS-COV-2 immunoglobulin G was 0.77. Comparison of vaccinated and recovered COVID-19 patients revealed significantly higher SARS-CoV-2 immunoglobulin G levels in maternal serum and cord blood among vaccinated women (P<.0001). CONCLUSION: Our study demonstrated the efficient transfer of SARS-CoV-2 immunoglobulin G across the placenta in women, vaccinated with the BNT162b2 messenger RNA vaccine during pregnancy, to their neonates, with a positive correlation between maternal serum and cord blood antibody concentrations. In addition to maternal protection against COVID-19, the vaccine may also provide neonatal humoral immunity.

Pregnancy and neonatal outcomes of twin pregnancies - the role of maternal age.

OBJECTIVES: We aim to study the association of maternal age with maternal and neonatal complications in twin pregnancies. METHODS: A retrospective cohort study of dichorionic-diamniotic twin pregnancies stratified into three groups according to maternal age ("A" <25, "B" 25-34 and "C" 35-44 years old). Outcome measures included pregnancy, delivery and neonatal complications. A sub-analysis of in vitro fertilization pregnancies only was conducted. RESULTS: Compared with younger women (groups A [n=65] and B [n=783]), older women [group C (n=392)] demonstrated significantly higher rates of gestational diabetes mellitus (B 6.6% vs. A 0%, p =0.027, C 10.2% vs. B 6.6%, p =0.032), were more likely to undergo cesarean deliveries (C 66.6%, B 57.6%, A 52.3%, p =0.007), and were at increased risk of having more than 20% difference in weight between the twins (C 24.5%, B 17.4%, A 16.9%, p =0.013). Other outcomes, including preeclampsia, did not differ between the groups. A sub-analysis of the in vitro fertilization only pregnancies was performed. Compared with younger women (groups A [n=18] and B [n=388]), older women (group C [n=230]) underwent more cesarean deliveries (p=0.004), and had more than 20% difference in weight between the twins (p<0.004). Other outcomes, including gestational diabetes mellitus rates and preeclampsia, did not differ between the groups. CONCLUSIONS: Women at advanced maternal age with dichorionic twin pregnancies had significantly higher rates of gestational diabetes mellitus, cesarean deliveries and fetal weight discordancy as compared with younger women. In contrast, the incidence of preeclampsia was not affected by maternal age.

Long-term follow-up on fetuses with isolated sonographic finding of short long bones: a cohort study.

PURPOSE: To evaluate the long-term outcome of fetuses with a diagnosis of isolated short long bones. METHODS: A retrospective review was conducted of all cases diagnosed with short long bones above 20 weeks of gestation during 2010-2017 in a single tertiary center. Exclusion criteria included abnormal sonographic findings other than short long bones, suspected genetic syndromes, chromosomal abnormalities, and abnormal Doppler flow indices. Follow-up was carried out by telephone questionnaire. RESULTS: During the study period, 54 (24.32%) women met inclusion criteria. Mean gestational age at delivery was 38.05 years (± 2.42 SD). Mean birth weight was 12-19th percentile according to the local fetal growth charts [2645 g (± 684 SD) 95% CI 2173-2980]. Median time for post-natal follow-up was 9.3 years (IQR 6.6-10.75). Growth below the 10th percentile was demonstrated in 27 (50%) children. 11 (20.37%) children were followed up by endocrinological clinics, of them 7 (12.96%) were treated with growth hormone. Three (5.6%) of the children were diagnosed with attention deficit hyperactivity disorder, an incidence that is considered lower than that of the general population (± 9%). CONCLUSIONS: Prenatal fetal isolated short long bones diagnosed during the late second and third trimester is associated with short stature. No neurodevelopmental impact was observed in our study group.

Immediate and delayed hyperbaric oxygen therapy as a neuroprotective treatment for traumatic brain injury in mice.

BACKGROUND: Traumatic brain injury is the most common cause of death or chronic disability among people under-35-years-old. There is no effective pharmacological treatment currently existing for TBI. Hyperbaric oxygen therapy (HBOT) is defined as the inhalation of pure oxygen in a hyperbaric chamber that is pressurized higher than 1atm. HBOT offers physiological and mechanical effects by inducing a state of increased pressure and hyperoxia. HBOT has been proposed as an effective treatment for moderate traumatic brain injury (mTBI), yet the exact therapeutic window and mechanism that underlies this effect is not completely understood. METHODS: HBOT was administrated for 4 consecutive days, post a mouse closed head weight drop moderate TBI (mTBI) in 2 different time lines: immediate treatment - initiated 3h post-injury and delayed treatment - initiated 7days post-injury. Behavioral cognitive tests and biochemical changes were assessed. RESULTS: The results were similar for both the immediate and the delayed treatments. mTBI mice exhibited impairment in learning abilities, whereas mTBI mice treated with HBO displayed significant improvement compared with the mTBI group, performing similar to the sham groups. mTBI mice had a decline in myelin basic protein, an increase in neuronal loss (NeuN staining), and an increase in the number of reactive astrocytes (GFAP). The HBO treated mice in both groups did not exhibit these changes and remained similar to the sham group. CONCLUSIONS: The delayed HBOT has a potential to serve as a neuroprotective treatment for mTBI with a long therapeutic window. Further research is needed for fully understanding the cellular changes.