Primary dysmenorrhoea, otherwise known as painful periods without any organic cause, is one of the most common gynaecological problems among women of childbearing age.
Between four and nine out of 10 women are thought to suffer from painful periods, and in around 10 to 15% of cases, the pain is severe and disabling.
The US research team assessed the role of perceived stress during the preceding menstrual cycle on the rate of painful periods in the next cycle.
The study included an analysis of 1160 menstrual cycles in 388 healthy, newly married women, none of whom had had a child, but all of whom wanted to become pregnant.
All the women, who were aged between 20 and 34, kept daily diaries charting their stress levels according to whether they were low, medium, or high, for up to 12 months or until pregnancy occurred.
They were also asked to provide information on their menstrual cycles, use of contraception, and levels of exposure to tobacco smoke, both as active and passive smokers.
The women were all textile workers, working in a rapidly growing economy in Anqing City, Anhui Province, China. A high proportion of them worked shifts and were exposed to varying levels of noise and dust.
The rate of dysmenorrhoea, defined as two or more days of abdominal and/or low back pain during a menstrual period, was just over 44%.