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Objective: To examine the duration and magnitude of increased risk of venous thromboembolism after different types of surgery., Design: Prospective cohort study (Million Women Study)., Setting: Questionnaire data from the Million Women Study linked with hospital admission and death records., Participants: 947 454 middle aged women in the United Kingdom recruited in 1996-2001 and followed by record linkage to routinely collected NHS data on hospital admissions and deaths. During follow-up 239 614 admissions were for surgery; 5419 women were admitted, and a further 270 died, from venous thromboembolism., Main Outcome Measures: Adjusted relative risks and standardised incidence rates for hospital admission or death from venous thromboembolism (pulmonary embolism or deep vein thrombosis), by time since and type of surgery., Results: Compared with not having surgery, women were 70 times more likely to be admitted with venous thromboembolism in the first six weeks after an inpatient operation (relative risk 69.1, 95% confidence interval 63.1 to 75.6) and 10 times more likely after a day case operation (9.6, 8.0 to 11.5). The risks were lower but still substantially increased 7-12 weeks after surgery (19.6, 16.6 to 23.1 and 5.5, 4.3 to 7.0, respectively). This pattern of risk was similar for pulmonary embolism (n=2487) and deep venous thrombosis (n=3529). The postoperative risks of venous thromboembolism varied considerably by surgery type, with highest relative risks after inpatient surgery for hip or knee replacement and for cancer-1-6 weeks after surgery the relative risks were, respectively, 220.6 (187.8 to 259.2) and 91.6 (73.9 to 113.4)., Conclusion: The risk of deep vein thrombosis and pulmonary embolism after surgery is substantially increased in the first 12 postoperative weeks, and varies considerably by type of surgery. An estimated 1 in 140 middle aged women undergoing inpatient surgery in the UK will be admitted with venous thromboembolism during the 12 weeks after surgery (1 in 45 after hip or knee replacement and 1 in 85 after surgery for cancer), compared with 1 in 815 after day case surgery and only 1 in 6200 women during a 12 week period without surgery.

Background: While parous women are known to be at an increased risk of gallbladder disease, little is known about the effects of other reproductive factors such as breastfeeding, age at menarche and age at menopause., Methods: The Million Women Study is a prospective cohort study of 1.3 million middle-aged women in England and Scotland recruited from 1996 to 2001. Participants were followed-up by record-linkage for a mean of 6.1 years for admissions to hospital. The adjusted relative risk of hospital admission for cholelithiasis, cholecystitis or cholecystectomy according to parity, breastfeeding, age at menarche and age at menopause was examined., Results: During follow-up of 1 289 029 eligible women, 25 111 were admitted to hospital for gallbladder disease, of whom 21 735 (87%) had a cholecystectomy. The hospital admission rate over 5 years for gallbladder disease was 1.6/100 women and for cholecystectomy was 1.4/100 women. The adjusted relative risk of gallbladder disease increased with increasing parity by 8% (95% CI 7-9%, P < 0.0001) for each birth. Among women of a given parity, breastfeeding reduced the risk of gallbladder disease, the relative risk decreasing by 7% (95% CI 5-10%, P < 0.0001) per year of breastfeeding. Women's age of menarche and age at menopause did not alter the risk of gallbladder disease (P = 0.4 and P = 0.3, respectively for linear trend)., Conclusion: Hospitalization for gallbladder disease is common in middle-aged women. The risk increases the more children a woman has had, but decreases the longer she breastfeeds. The increased risk of gallbladder disease associated with having children can be offset by breastfeeding.

Objective: To determine whether transdermal compared with oral use of hormone replacement therapy reduces the risk of gallbladder disease in postmenopausal women., Design: Prospective cohort study (Million Women Study)., Setting: Women registered with the National Health Service (NHS) in England and Scotland., Participants: 1,001,391 postmenopausal women (mean age 56) recruited between 1996 and 2001 from NHS breast screening centres and followed by record linkage to routinely collected NHS hospital admission data for gallbladder disease., Main Outcome Measures: Adjusted relative risk and standardised incidence rates of hospital admission for gallbladder disease or cholecystectomy according to use of hormone replacement therapy., Results: During follow-up 19 889 women were admitted for gallbladder disease; 17 190 (86%) had a cholecystectomy. Compared with never users of hormone replacement therapy, current users were more likely to be admitted for gallbladder disease (relative risk 1.64, 95% confidence interval 1.58 to 1.69) but risks were substantially lower with transdermal therapy than with oral therapy (relative risk 1.17, 1.10 to 1.24 v 1.74, 1.68 to 1.80; heterogeneity P<0.001). Among women using oral therapy, equine oestrogens were associated with a slightly greater risk of gallbladder disease than estradiol (relative risk 1.79, 1.72 to 1.87 v 1.62, 1.54 to 1.70; heterogeneity P<0.001) and higher doses of oestrogen increased the risk more than lower doses: for equine oestrogens >0.625 mg, 1.91 (1.78 to 2.04) v 1 mg, 1.68 (1.59 to 1.77) v

Background: Obesity increases the risk of hospital admission for gallbladder disease but its impact on the length of hospital stay is largely unknown., Methods: Prospective population-based study of 1.3 million women aged 56 years on average, recruited from 1996 to 2001 in England and Scotland and followed-up through NHS hospital admission record databases for gallbladder disease (cholelithiasis, cholecystitis, cholecystectomy) over a total of 7.8 million person-years., Results: During follow-up, 24 953 women were admitted with gallbladder disease, 87% who had a cholecystectomy. After adjusting for age, socioeconomic status and other factors, women with higher BMI at recruitment to the study were more likely to be admitted and spend more days in hospital. For 1000 person-years of follow-up, women in BMI categories of 18.5-24.9, 25-29.9, 30-39.9, 40+ kg/m(2) spent, respectively, 16.5[16.0-17.0], 28.6[28.3-28.8], 44.0[43.4-44.5] and 49.4[45.7-53.0] days in hospital for gallbladder disease., Conclusion: On the basis of these estimates, over a quarter of all the days in hospital for gallbladder disease in middle-aged women can be attributed to obesity.

Objectives: To examine the validity of self-reported primary hip replacement, primary knee replacement, and cholecystectomy., Study Design and Setting: The data from 28,524 participants in the Million Women Study who were recruited from Scotland were linked with routinely collected Scottish hospital admission data. We compared the reporting of three operations by the study participants on a postal questionnaire with that recorded in the hospital admission database., Results: Annual incidence rates for the three operations were similar using hospital admission and self-reported data at: 2.1 (n=220) and 2.3 (n=247) per 1,000 women, respectively, for hip replacement; 1.1 per 1,000 women from both sources for knee replacement (n=118 and n=116, respectively); and 3.4 (n=357) and 3.2 (n=344) per 1,000 women, respectively, for cholecystectomy. Agreement between self-report and the hospital admission records was good for all three operations with agreements of 99.8%, 99.9%, and 99.6% for hip replacement, knee replacement, and cholecystectomy, respectively., Conclusion: In middle-aged women who answered postal questionnaires, self-reporting of primary hip replacement, primary knee replacement, and cholecystectomy was found to agree well with information held in a medical record database.

Setting: The Million Women Study is a cohort study of women aged 50-64 years in England and Scotland. As a component of the follow-up questionnaire, participants were asked to indicate if they had an abnormal cervical smear in the previous five years. This study compared self-reported cervical abnormalities with screening records obtained from the National Health Service Cervical Screening Programme., Methods: For 1944 randomly selected Million Women Study participants in Oxfordshire, screening records were assessed over a six-year period prior to the date of self-reporting. The six-year period was chosen to allow for errors in the recall of timing of abnormal smears., Results: A total of 68 women (3.5%) had a record of at least one equivocal or abnormal smear within the last six years, whereas 49 women (2.5%) self-reported an abnormality. There was a strong trend for an increased probability of self-reporting a history of an abnormal smear as the severity of the recorded abnormality increased (P <0.001). For women with an NHS record of borderline dyskaryosis, mild dyskaryosis, or moderate dyskaryosis/severe dyskaryosis/invasive cancer, the proportions reporting an abnormality were 40%, 58% and 77%, respectively. For women with negative and inadequate smears, the proportion self-reporting an abnormality were 0.6% and 0.7%, respectively., Conclusions: These results indicate that among women whose screening programme records show an abnormal smear, the proportion self-reporting an abnormality increases with the severity of the recorded lesion. Almost all women with a record of negative or inadequate smear(s) correctly interpret the result and do not self-report an abnormality.

Study Objective: To assess the risk of breast cancer in patients with a previous history of miscarriage or induced abortion., Design: Case-control study relating "exposure" to outcome by linkage of national hospital discharge and maternity records, the national cancer registry, and death records., Setting: Scotland., Participants: Miscarriage analysis-2828 women with breast cancer and 9781 matched controls; induced abortion analysis-2833 women with breast cancer and 9888 matched controls., Main Results: After stratification for age at diagnosis, parity, and age at first birth, the odds ratio (95% confidence intervals) of breast cancer was 1.02 (0.88 to 1.18) in women with a previous miscarriage, and 0.80 (0.72 to 0.89) in women with a previous induced abortion. Further adjustments for age at bilateral oophorectomy, socioeconomic status (based on small area of residence), and health board area of residence had only minor effects on these odds ratios., Conclusion: These data do not support the hypothesis that miscarriage or induced abortion represent substantive risk factors for the future development of breast cancer.

The relation between prematurity and parenteral occupation was examined in a national study of 252,147 liveborn babies delivered in Scotland between 1981 and 1984. Information about mothers' and fathers' work was routinely collected at the first antenatal visit, and birthweight and gestational age were recorded at delivery. Preterm delivery (less than 37 weeks' gestation) and low birthweight (less than 2500 g) were more frequent in the children of mothers and of fathers employed in manual rather than in non-manual jobs. The risk of preterm delivery and/or low birthweight was more than 50% higher in the children of women who worked with electrical, metal, or leather goods than in the children of other female manual workers. These findings were not explained by maternal age, gravidity, marital status, previous perinatal death, baby's sex, or father's social class. For male manual workers, only the children of ceramic workers had an increased risk of prematurity. The risk of a baby being small-for-gestational age (less than or equal to 5th gestation-specific birthweight percentile) varied little with mother's or father's occupation. Overall, the results suggest that parental occupational exposures do not have a pronounced effect on the risk of prematurity, and when there are adverse effects they are associated with maternal rather than paternal exposures.