Objective: To analyze the association between tea drinking during pregnancy and the risk of preterm delivery and abortion,so as to provide basis for prevention of preterm delivery and abortion. Methods: The databases of CNKI,Wanfang,VIP,CBMdisc,PubMed and Web of Science were searched for cohort studies and case-control studies into the association between tea consumption during pregnancy and preterm delivery or abortion until June 30 th,2019. Relative risk（RR）or odds ratio（OR）were used as indicators for the meta-analysis. Results: A total of 1 099 articles were retrieved,14 of them were included in the quantitative study,including 9 cohort studies with 18 295 exposed and 71 890 unexposed individuals and 5 case-control studies with 1 351 cases and 3 059 controls. There was no statistically significant association between tea drinking during pregnancy and preterm birth or abortion（OR/RR=1.08,95%CI：0.99-1.18）. The linear regression model of random effect showed that with the increase of tea consumption during pregnancy,the risk of premature delivery and abortion did not change significantly（OR/RR=1.05，95%CI：0.99-1.11）. There was no publication bias found in Begg's test and Egger's test. Conclusion Drinking tea during pregnancy is not associated with preterm delivery and abortion.

The aim of the present study was to investigate the effects of exosomes derived from bone marrow mesenchymal stem cells (BMSCs) on the polarization of M1/M2 microglia/macrophages in rats with acute cerebral ischemia.Ultrahigh-speed centrifugation was employed to isolate and identify exosomes; a middle cerebral artery occlusion (MCAO) model was prepared in rats using the intraluminal filament technique; Longa scoring and corner tests were used to evaluate the neurological function of rats; 2, 3, 5-triphenyltetrazole chloride (TTC) staining was used to assess the infarct volume in rat brains; immunofluorescence double-labeling of CD16/32/Iba1 and CD206/Iba1 was performed to detect M1/M2 phenotypes of microglia/macrophages; RT-qPCR was employed to measure the mRNA expression of CD86, inducible nitric oxide synthase (iNOS), tumor necrosis factor-alpha (TNF-α), arginase-1 (Arg-1), interleukin-10 (IL-10), and transforming growth factor beta (TGF-β) in the ischemic penumbra of rat brains.The experimental results showed that BMSC-Exos reduced the number of CD16/32+/Iba1+ positive cells in the ischemic penumbra (P < 0.01) while increasing the number of CD206+/Iba1+positive cells (P < 0.01), and decreased the mRNA expression of iNOS, CD86, and TNF-α, while increasing the mRNA expression of Arg-1, TGF-β, and IL-10 (P < 0.05 or P < 0.01).This research suggests that BMSC-Exos can regulate M1/M2 polarization of microglia/macrophages in rats with acute cerebral ischemia, alleviate neuroinflammation, and improve ischemic brain injury.