To examine the relationship between number of livebirths and cesarean sections on the development of menstrual abnormalities. Methods: The effect of number of livebirths and cesarean sections on menstrual abnormalitie...To examine the relationship between number of livebirths and cesarean sections on the development of menstrual abnormalities. Methods: The effect of number of livebirths and cesarean sections on menstrual abnormalities in the late reproductive period was evaluated using data from the Harvard Study of Moods and Cycles. Results: There were 298 women with no livebirths and 606 women with livebirths of which 184 had a history of cesarean section. Among all women, increasing number of livebirths was associated with an increasing trend in reported heavy menses, prolonged flow > 6 days, and a decreasing trend in reported dysmenorrhea. This effect was amplified among women with a history of cesarean section. Conclusions: Increasing number of livebirths is associated with heavy and prolonged menstrual flow during the late reproductive period. This association is particularly stronger in women with a history of cesarean section.展开更多
Ambient air pollution in China has worsened following dramatic increases in industrialization, automobile use and energy consumption. Particularly bothersome is the increase in the PM2.5 fraction of pollutants. This f...Ambient air pollution in China has worsened following dramatic increases in industrialization, automobile use and energy consumption. Particularly bothersome is the increase in the PM2.5 fraction of pollutants. This fraction has been associated with increasing rates of cardio-respiratory disease in China and elsewhere. Ambient pollutant levels have been described in many of China＇s cities and are comparable to previous levels in southern California. Lung cancer mortality in China has increased since the 1970s and has been higher in men and in urban areas, the exact explanation for which has not been determined. The estimation of individual risk for Chinese citizens living in areas of air pollution will require further research. Occupational cohort and casecontrol designs each have unique attributes that could make them helpful to use in this setting. Other important future research considerations include detailed exposure assessment and the possible use of biomarkers as a means to better understand and manage the threat posed by air pollution in China.展开更多
文摘To examine the relationship between number of livebirths and cesarean sections on the development of menstrual abnormalities. Methods: The effect of number of livebirths and cesarean sections on menstrual abnormalities in the late reproductive period was evaluated using data from the Harvard Study of Moods and Cycles. Results: There were 298 women with no livebirths and 606 women with livebirths of which 184 had a history of cesarean section. Among all women, increasing number of livebirths was associated with an increasing trend in reported heavy menses, prolonged flow > 6 days, and a decreasing trend in reported dysmenorrhea. This effect was amplified among women with a history of cesarean section. Conclusions: Increasing number of livebirths is associated with heavy and prolonged menstrual flow during the late reproductive period. This association is particularly stronger in women with a history of cesarean section.
文摘Ambient air pollution in China has worsened following dramatic increases in industrialization, automobile use and energy consumption. Particularly bothersome is the increase in the PM2.5 fraction of pollutants. This fraction has been associated with increasing rates of cardio-respiratory disease in China and elsewhere. Ambient pollutant levels have been described in many of China＇s cities and are comparable to previous levels in southern California. Lung cancer mortality in China has increased since the 1970s and has been higher in men and in urban areas, the exact explanation for which has not been determined. The estimation of individual risk for Chinese citizens living in areas of air pollution will require further research. Occupational cohort and casecontrol designs each have unique attributes that could make them helpful to use in this setting. Other important future research considerations include detailed exposure assessment and the possible use of biomarkers as a means to better understand and manage the threat posed by air pollution in China.
