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Decadal trends in the properties of seawater adjacent to Antarctica are poorly known, and the mechanisms responsible for such changes are uncertain. Antarctic ice sheet mass loss is largely driven by ice shelf basal melt, which is influenced by ocean-ice interactions and has been correlated with Antarctic Continental Shelf Bottom Water (ASBW) temperature. We document the spatial distribution of long-term large-scale trends in temperature, salinity, and core depth over the Antarctic continental shelf and slope. Warming at the seabed in the Bellingshausen and Amundsen seas is linked to increased heat content and to a shoaling of the mid-depth temperature maximum over the continental slope, allowing warmer, saltier water greater access to the shelf in recent years. Regions of ASBW warming are those exhibiting increased ice shelf melt.

To verify whether body mass index (BMI) classification proposed by the Institute of Medicine (IOM) is valid in Japanese women. A study was conducted in 97,157 women with singleton pregnancies registered in the Japan Society of Obstetrics and Gynecology (JSOG) Successive Pregnancy Birth Registry System between January 2013 and December 2013, to examine pregnancy outcomes in four groups stratified by pre-pregnancy BMI category according to the 2009 criteria recommended by the Institute of Medicine (IOM). The groups comprised 17,724 underweight women with BMI <18.5, 69,126 normal weight women with BMI 18.5-24.9, 7,502 overweight women with BMI 25-29.9, and 2,805 obese women with BMI ≥30. The pregnancy outcomes were also compared among subgroups stratified by a gestational weight gain below, within, and above the optimal weight gain. The higher the pre-pregnancy BMI, the higher the incidences of pregnancy-induced hypertension, gestational diabetes mellitus, macrosomia, cesarean delivery, postpartum hemorrhage, and post-term birth, but the lower the incidence of small for gestational age (SGA). In all pre-pregnancy BMI category groups, excess gestational weight gain was associated with a higher frequency of large for gestational age and macrosomia; poor weight gain correlated with a higher frequency of SGA, preterm birth, preterm premature rupture of membranes, and spontaneous preterm birth; and optimal weight gain within the recommended range was associated with a better outcome. The BMI classification by the IOM was demonstrated to be valid in Japanese women.

Basal melting of ice shelves is considered to be the principal driver of recent ice mass loss in Antarctica. Nevertheless, in-situ oceanic data covering the extensive areas of a subshelf cavity are sparse. Here we show comprehensive structures of temperature, salinity and current measured in January 2018 through four boreholes drilled at a ~3-km-long ice shelf of Langhovde Glacier in East Antarctica. The measurements were performed in 302–12 m-thick ocean cavity beneath 234–412 m-thick ice shelf. The data indicate that Modified Warm Deep Water is transported into the grounding zone beneath a stratified buoyant plume. Water at the ice-ocean interface was warmer than the in-situ freezing point by 0.65–0.95°C, leading to a mean basal melt rate estimate of 1.42 m a −1 . Our measurements indicate the existence of a density-driven water circulation in the cavity beneath the ice shelf of Langhovde Glacier, similar to that proposed for warm-ocean cavities of larger Antarctic ice shelves. Basal melting of ice shelves is the principal driver of recent ice mass loss in Antarctica. The study reports comprehensive structures of temperature, salinity and current under an ice shelf in East Antarctica obtained by borehole measurements.

Mass loss from the Antarctic ice sheet, Earth’s largest freshwater reservoir, results directly in global sea-level rise and Southern Ocean freshening. Observational and modeling studies have demonstrated that ice shelf basal melting, resulting from the inflow of warm water onto the Antarctic continental shelf, plays a key role in the ice sheet’s mass balance. In recent decades, warm ocean-cryosphere interaction in the Amundsen and Bellingshausen seas has received a great deal of attention. However, except for Totten Ice Shelf, East Antarctic ice shelves typically have cold ice cavities with low basal melt rates. Here we present direct observational evidence of high basal melt rates (7–16 m yr −1 ) beneath an East Antarctic ice shelf, Shirase Glacier Tongue, driven by southward-flowing warm water guided by a deep continuous trough extending to the continental slope. The strength of the alongshore wind controls the thickness of the inflowing warm water layer and the rate of basal melting. East Antarctic ice shelves typically have cold ice cavities with low basal melt rates. Here the authors direct observational evidence of high basal melt rates beneath Shirase Glacier Tongue in East Antarctica, driven by inflowing warm water guided by a deep continuous trough extending to the continental slope.

Previous studies have shown that interpregnancy weight fluctuations impact perinatal outcomes. In order to examine this in Japanese women, we analyzed the data of 2,861 women in their first and second pregnancies who delivered singletons between 2000 and 2022. We compared the second pregnancy perinatal outcomes of women whose interpregnancy body mass index (BMI) change was -1 to 1 unit with those of women whose BMI change was < -1 or ≥ 1 unit. An interpregnancy BMI change ≥ 1 unit was associated with an increased risk of developing gestational diabetes mellitus (adjusted odds ratio [aOR], 1.51; 95% confidence interval [CI], 1.18–1.95) and delivering a large for gestational age neonate (aOR, 1.67; 95% CI, 1.15–2.42) but a decreased risk of preterm birth (aOR, 0.66; 95% CI, 0.46–0.95). An interpregnancy BMI change < -1 unit was associated with a decreased risk of developing gestational diabetes mellitus (aOR, 0.51; 95% CI, 0.31–0.85). In a subgroup analysis of three groups divided according to prepregnancy BMI, interpregnancy BMI changes ≥ 1 unit in women with a BMI of < 18.5 kg/m2 before their first pregnancy were associated with a remarkable risk reduction of developing preterm birth (aOR, 0.30; 95% CI, 0.11–0.81). Interpregnancy BMI changes < -1 unit in women with a BMI of ≥ 25 kg/m 2 before their first pregnancy were associated with a remarkable risk reduction of developing gestational diabetes mellitus (aOR, 0.33; 95% CI, 0.12–0.88). Weight gain during interpregnancy period was related to an increased risk of gestational diabetes mellitus and delivery of a large-for-gestational-age neonate, whereas weight loss was related to a decreased risk of developing gestational diabetes mellitus. These results indicate the importance of interpregnancy weight control as part of preconception care; therefore, women considering additional pregnancies should be educated on the importance of maintaining a healthy weight.

The formation of Antarctic Bottom Water—the cold, dense water that occupies the abyssal layer of the global ocean—is a key process in global ocean circulation. This water mass is formed as dense shelf water sinks to depth. Three regions around Antarctica where this process takes place have been previously documented. The presence of another source has been identified in hydrographic and tracer data, although the site of formation is not well constrained. Here we document the formation of dense shelf water in the Cape Darnley polynya (65°–69° E) and its subsequent transformation into bottom water using data from moorings and instrumented elephant seals ( Mirounga leonina ). Unlike the previously identified sources of Antarctic Bottom Water, which require the presence of an ice shelf or a large storage volume, bottom water production at the Cape Darnley polynya is driven primarily by the flux of salt released by sea-ice formation. We estimate that about 0.3–0.7×10 6  m 3  s −1 of dense shelf water produced by the Cape Darnley polynya is transformed into Antarctic Bottom Water. The transformation of this water mass, which we term Cape Darnley Bottom Water, accounts for 6–13% of the circumpolar total. Antarctic Bottom Water fills much of the global abyssal ocean, and is known to form in three main sites in the Southern Ocean. Data from instrumented elephant seals and moorings suggest an additional source of bottom-water formation in the Cape Darnley polynya that is driven by sea-ice production.

The aim of this study was to examine how physical activity (PA) before and during pregnancy influences pregnancy outcomes, particularly preterm delivery and mode of delivery. This study was based on the Japan Environment and Children's Study. A total of 92,796 pregnant women who gave birth to live singleton babies were included. Information on mean PA per week during pregnancy was extracted from the responses to questionnaires completed by women during the second and third trimesters of pregnancy. Information on PA before pregnancy was obtained from questionnaires answered based on recall at participation. The level of PA was stratified into the following quartiles for categorical analysis: Very low, Low, Medium, and High. Pregnancy outcomes, gestational age at delivery (whether preterm delivery or not), and mode of delivery (spontaneous, instrumental, or caesarean delivery) were compared between the different groups adjusted for multiple covariates. With respect to PA during pregnancy, the risk of preterm delivery and instrumental delivery increased significantly in the Very low group compared to that in the Medium group (odds ratios [OR] 1.16, 95% confidence interval [CI], 1.05-1.29; OR 1.12, 95% CI, 1.03-1.22, respectively). Moreover, the risks of caesarean delivery in the Low group and instrumental delivery in the High group were significantly higher than the risks in the Medium group (OR 1.07, 95% CI, 1.00-1.15; OR 1.12, 95% CI, 1.02-1.22, respectively). In contrast, with respect to PA before pregnancy, there were no statistically significant differences when the other groups were compared to the Medium group. Pre-pregnancy PA has no negative effects on preterm birth and caesarean delivery. In contrast, both may be affected by PA during pregnancy because a low level of PA appears to slightly increase the risk of preterm delivery and operative delivery (caesarean and instrumental).

ObjectivesTo estimate uptake of the 75 g oral glucose tolerance test (OGTT) at 6–12 weeks postpartum among women with gestational diabetes mellitus (GDM) in Japan, and to explore the demographic and clinical characteristics associated with screening uptake.DesignRetrospective cohort study using administrative claims data.SettingData from a nationwide employees’ health insurance claims database (Japan Medical Data Center; JMDC) during the fiscal years 2012–2020 were assessed.Participants2282 women with GDM in the JMDC claims database (April 2012–January 2021), ascertained using the International Classification of Diseases 10th revision (ICD-10) codes cross-validated with a high-risk GDM management fee.Primary and secondary outcome measuresPrimary outcome: completion of a 75 g OGTT at 6–12 weeks postpartum. Secondary outcomes: completion of a 75 g OGTT at 4–12 weeks postpartum and cumulative completion up to 1 year postpartum.ResultsWe included 2282 women in the analysis. The overall screening rate was 28.7% (654/2282) from 2012 to 2020. Even in 2020, the year with the highest reported screening rate, it remained low at 33.2% (181/546). After expanding the range to include 4 weeks to ≤1 year postpartum, the cumulative screening rate reached 64.9% by 1 year postpartum. The screening rate was lower when childbirth and GDM were managed at different facilities than when both were managed within the same facility.ConclusionsWe report suboptimal screening rates for women with a GDM history in Japan. This study highlights the need for continuous monitoring and the development of effective strategies for early screening and intervention in this high-risk group. These strategies should include system-level improvements in screening methods and enhance patient awareness through antenatal education prior to delivery.

In 2009, the United States Institute of Medicine (IOM) reported the optimal gestational weight gain (GWG) during twin pregnancy based on the pre-pregnancy body mass index (BMI). However, there are ethnic variations in the relationship between GWG and pregnancy outcomes. We aimed to establish the criteria for optimal GWG during twin pregnancy in Japan. The study included cases of dichorionic diamniotic twin pregnancy registered in the Japan Society of Obstetrics and Gynecology Successive Pregnancy Birth Registry System between 2013 and 2017. We analyzed data for cases wherein both babies were appropriate for gestational age and delivered at term. Cases were classified into four groups based on the pre-pregnancy BMI: underweight (BMI <18.5 kg/m 2 ), normal weight (18.5 kg/m 2 ≤BMI< 25.0 kg/m 2 ), overweight (25.0 kg/m 2 ≤BMI< 30.0 kg/m 2 ), and obese (BMI ≥30.0 kg/m 2 ) and we calculated the 25 th –75 th percentile range for GWG for the cases. The 3,936 cases were included. The GWG ranges were 11.5–16.5 kg, 10.3–16.0 kg, 6.9–14.7 kg, and 2.2–11.7 kg in the underweight, normal weight, overweight, and obese groups, respectively. Thus, in the current study, the optimal GWG during twin pregnancy was lower than that specified by the IOM criteria. Factoring this in maternal management may improve the outcomes of twin pregnancies in Japan.

Antarctic coastal polynyas provide extremely dense water to the global abyss, but the dense water formation process has been poorly monitored in winter. This study developed a new tethered profiler to realize time-series observations of the water column in the Cape Darnley Polynya, East Antarctica. The system successfully obtained temperature and salinity profiles at 10-day intervals from March to November 2017. From March to April, significant cooling and vertical mixing started, while stratification collapsed. Salinity increased rapidly from April to late-May and then gradually increased until October. Salinity development was largely consistent with the cumulative salt increase due to sea-ice production at the initial stage, but not at latter stages, indicating the influence of cross-shelf exchange. These results highlighted the potential of the measurement platform to fill the remaining gap in the global ocean monitoring network.