Factors Affecting the Risk of Postpartum Hemorrhage in Pregnant Women in Tibet Health Facilities.

BACKGROUND Postpartum hemorrhage (PPH), the leading cause of maternal death, is defined as a blood loss >500 mL within 24 h after vaginal delivery or >1000 mL within 24 h after cesarean section. This study aimed to investigate the incidence of PPH and assess its risk factors in pregnant women in Tibet to provide a reference for clinicians in this region. MATERIAL AND METHODS A total of 4796 pregnant women with gestational age ≥28 weeks who were admitted to hospitals in Tibet between December 2010 and December 2016 were involved in this study. Patient sociological and clinical data and pregnancy outcomes were collected. The related risk factors of PPH were analyzed by univariate and multivariable logistic regression. The area under the curve of the receiver operating characteristic curves was used to evaluate the effect of the PPH prediction model. RESULTS PPH occurred in 95 women, with an incidence of 1.98%. The following factors were associated with higher risk for PPH: maternal age ≥35 (odds ratio [OR]=1.96; 95% confidence interval [CI], 1.18-3.27; P=0.010), history of preterm birth (OR=2.66; 95% CI, 1.60-4.42; P<0.001), cesarean section (OR=6.69; 95% CI, 4.30-10.40; P<0.001), neonatal weight >4 kg (OR=3.92; 95% CI, 1.75-8.81; P<0.001) and occurrence of neonatal asphyxia (OR=5.52; 95% CI, 2.22-13.74; P<0.001). CONCLUSIONS Maternal age ≥35, history of preterm birth, cesarean section, newborn weight >4 kg, and neonatal asphyxia were risk factors of PPH, which can help evaluate PPH in Tibet.

Forest biomass carbon pool dynamics in Tibet Autonomous Region of China: Inventory data 1999-2019.

According to the forest resources inventory data for different periods and the latest estimation parameters of forest carbon reserves in China, the carbon reserves and carbon density of forest biomass in the Tibet Autonomous Region from 1999 to 2019 were estimated using the IPCC international carbon reserves estimation model. The results showed that, during the past 20 years, the forest area, forest stock, and biomass carbon storage in Tibet have been steadily increasing, with an average annual increase of 1.85×104 hm2, 0.033×107 m3, and 0.22×107 t, respectively. Influenced by geographical conditions and the natural environment, the forest area and biomass carbon storage gradually increased from the northwest to the southeast, particularly in Linzhi and Changdu, where there are many primitive forests, which serve as important carbon sinks in Tibet. In terms of the composition of tree species, coniferous forests are dominant in Tibet, particularly those containing Abies fabri, Picea asperata, and Pinus densata, which comprise approximately 45% of the total forest area in Tibet. The ecological location of Tibet has resulted in the area being dominated by shelter forest, comprising 68.76% of the total area, 64.72% of the total forest stock, and 66.34% of the total biomass carbon reserves. The biomass carbon storage was observed to first increase and then decrease with increasing forest age, which is primarily caused by tree growth characteristics. In over-mature forests, trees' photosynthesis decreases along with their accumulation of organic matter, and the trees can die. In addition, this study also observed that the proportion of mature and over-mature forest in Tibet is excessively large, which is not conducive to the sustainable development of forestry in the region. This problem should be addressed in future management and utilization activities.