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Female residents of western Washington state aged 18-80 years in whom thyroid cancer was diagnosed between January 1974 and December 1979 were interviewed concerning their reproductive histories and their prior use of exogenous estrogens. Their responses were compared with those of a sample of women from the same population, individually matched to cases on telephone prefix. Use of each of several estrogen-containing preparations was associated with a small increased risk of thyroid cancer; parous women who had ever used a lactation suppressant had 1.7 times the risk of parous nonusers (95% confidence interval, 1.1-2.8); ever users of oral contraceptives had 1.6 times the risk of never users (95% confidence interval, 0.98-2.5); and ever users of postmenopausal estrogens had 1.4 times the risk of never users (95% confidence interval, 0.89-2.3). Among the low risk group of women, i.e., those who had never undergone radiation therapy and who had never had a goiter, a history of one or more pregnancies was also associated with a small increase in the risk of thyroid cancer (relative risk = 1.8, 95% confidence interval, 1.1-3.1). However, no increase in risk with increasing duration of use of oral contraceptives or menopausal estrogens or with increasing number of pregnancies was noted. While pregnancy and use of exogenous estrogens have an impact on the production of thyroid-stimulating hormone, their effect on the incidence of thyroid carcinoma, if present at all, appears to be small.

The prevalence of several known or suspected risk factors for breast cancer is changing among young women. The time trend in incidence of breast cancer among young women in western Washington was analyzed as a possible predictor of trends in future incidence rates. Data were from the Seattle-Puget Sound Surveillance, Epidemiology, and End Results cancer registry. For women age 25-44 years (n = 1,869 cases), the incidence of breast cancer increased by 22% (P less than .001) between the time periods 1974-77 and 1982-84. The estimated annual increase was 2.5% (P less than .001). The increase in incidence over time appeared to be greater among those residing in low-income census tracts of urban counties and among black women. Possible relationships between the observed increase in rates and trends of risk factors for breast cancer are discussed.

A nested case-control study was conducted to assess the relation between serum levels of selenium and retinol and the subsequent risk of cancer. During the years 1972-1984, in northwest Washington State, 156 cases of cancer were identified among members of two employee cohorts from whom specimens had been previously obtained and stored. Two hundred eighty-seven controls were selected from these cohorts and matched to cases on the basis of employer, age, sex, race, and date of blood draw. Selenium and retinol levels were measured by neutron activation and high pressure liquid chromatography, respectively. Information on known cancer risk factors was collected by telephone interviews of subjects and next of kin. Levels of selenium and retinol were unassociated with the incidence of cancer of all sites combined, both overall and within subgroups defined by age, sex, levels of the other micronutrient, time between blood draw and diagnosis, smoking status, and family history of cancer. These findings suggest that neither serum levels of selenium nor those of retinol have an appreciable effect on the risk of cancer.

From the practices of approximately two thirds of the orthopedic surgeons in King County, Washington, the authors identified white women ages 50 to 74 who had sustained a fracture of the hip or forearm between 1976 and 1979. The women were interviewed concerning factors associated with levels of endogenous estrogens. Their responses were compared to those of a random sample of white female residents of King County in the same age range. The risk of hip fracture was elevated in thin women and in those who smoked cigarettes, particularly among nonusers of estrogen. Neither weight nor smoking affected the risk of forearm fracture in estrogen users, although among nonusers smoking increased the risk, particularly among those who were thin. The beneficial effect of estrogen use in preventing both types of fracture varied considerably according to the woman's weight and smoking status, being greatest in thin women who smoked cigarettes and near zero in heavy nonsmokers. Body weight and cigarette smoking history offer important information concerning the probable degree of protection against fracture afforded by estrogen use.

The authors attempted to relate neonatal mortality to method of delivery in a series of 345 infants, weighing 700 to 1500 g, who were born in King County, Washington, from 1977 to 1979. Overall, 38% of infants delivered vaginally died as opposed to 32% of those with cesarean births. However, after adjustment for birth weight, presentation, and place of delivery, cesarean birth was not associated with reduction in mortality. Even among those infants with a breech presentation, a group believed (on the basis of previous studies) to particularly benefit from cesarean birth, the data failed to show any mortality reduction. Based on the results of this study of very low birth weight singleton infants, it appears that the reduced neonatal mortality associated with cesarean birth, if present at all, is small in magnitude.

To prevent pelvic inflammatory disease (PID) and its consequences, risk factors must be identified. A review of the literature supports the possibility that vaginal douching may affect the risk factor of PID, and new data are presented on douching practices of women hospitalized with PID. Individual case reports and controlled studies support associations between vaginal douching and both PID and ectopic pregnancy. The prevalence and distribution of douching are also compatible with a possible association. The temporal pattern of PID symptoms may be linked to douching and menses. The nature of the douche solution and the douching technique may be important variables with regard to douching as a PID risk factor. A case-control epidemiologic study is recommended to clarify the relationships between PID and douching.

Female residents of six counties in Washington and Utah in whom ovarian cancer was diagnosed during 1975-79 were interviewed concerning prior use of noncontraceptive estrogens. Interviews with a random sample of women drawn from these counties were obtained for comparison. Taken as a whole, women with epithelial ovarian tumors reported estrogen use for 1 year or more somewhat more often than did controls [relative risk (RR) = 1.3, 95% confidence interval (CL) = 0.9-1.8]. The proportion of women who had used estrogens varied according to the histology of their tumor; notably, of 17 women with endometrioid tumors, 12 had used estrogens (RR = 3.1, 95% CL = 1.0-9.8). The excess risk of endometrioid carcinoma related to estrogen use was not further increased when these hormones were taken for long durations, in high doses, or proximate to the time of diagnosis. Neither was there any evidence of increased risk from estrogen use in the small group of women with clear cell tumors, a histologic tumor type believed to be closely related to endometrioid carcinoma. Thus the observed association between menopausal estrogen use and the occurrence of ovarian endometrioid tumors should be interpreted cautiously until the results of additional studies are available.

A nested, matched case-control study was conducted to assess the relationship between serum levels of copper and the subsequent risk of cancer. One hundred thirty-three cases of cancer were identified during 1974-1984 among 5000 members of a northwest Washington State employee cohort from whom serum specimens had been previously obtained and stored. Two hundred forty-one controls were selected at random from the cohort and were matched to the cases on the basis of age, sex, race, and date of blood draw. Serum copper levels were measured by atomic absorption spectrometry. Risk of a subsequent diagnosis of cancer was positively associated with serum copper levels, but only among those cases diagnosed within 4 years of the time the serum specimens were collected. Among cases diagnosed more than 4 years after specimen collection, there was no consistent association between serum copper levels and risk. Adjustment for age, sex, race, occupational status, cigarette smoking, family history of cancer, alcohol consumption, and, among females, use of exogenous hormones had no appreciable effect on these relationships. The findings suggest that the presence of cancer may increase serum copper levels several years prior to its diagnosis. They are less supportive of the hypothesis that serum copper levels affect cancer risk.

This study assessed the effect of legal induced abortion on ectopic pregnancy risk by using a comparison group of reproductive-age women who were at risk of becoming pregnant during the same time period the women with ectopic pregnancy conceived. Cases were members of Group Health Cooperative of Puget Sound who were hospitalized for ectopic pregnancy from October 1981 through September 1986 (N = 211). Controls were randomly selected members matched to cases on age and county of residence (N = 457). All subjects in this analysis had had one or more prior pregnancies. Eighty-eight cases (41.7 per cent) and 177 controls (38.7 per cent) had a history of one or more induced abortions. The relative risk of ectopic pregnancy associated with one abortion was 0.9 (95 per cent confidence interval 0.6, 1.3), adjusted for age, county, reference date, religion, gravidity, age at first pregnancy, lifetime number of sexual partners, and miscarriage history. Among women with two or more prior pregnancies, the risk associated with two or more abortions was 1.2 (0.6, 2.4). Controlling for pelvic inflammatory disease and use of intrauterine devices did not alter these risks. We conclude that legal abortion as performed in the US since 1970 has little or no influence on a woman's risk of ectopic pregnancy in subsequent pregnancies.

One hundred forty-one women with tubal infertility, all of whom had been pregnant at least once before, were interviewed concerning their reproductive, contraceptive, medical, and sexual histories. Their responses were compared with those of a control group of 467 fertile women. A higher percentage of cases (13%) than controls (1%) had had a tubal pregnancy. From these percentages, we estimate that 92% of tubal infertility in women who have had a tubal pregnancy results from tubal pregnancy itself or factors that predisposed to its occurrence. We also estimate that approximately one-fifth of women who suffer a tubal pregnancy will subsequently be infertile because of a tubal abnormality. After controlling for the joint effects of several known risk factors for tubal pregnancy that independently predispose to infertility (eg, a history of pelvic inflammatory disease), the relative risk of tubal infertility associated with tubal pregnancy was 15.0 (95% confidence interval 5.2-43.6). However, because we had no sensitive indicator of antecedent tubal disease, we were extremely limited in our attempt to determine the extent to which this association was actually due to the consequences of the tubal pregnancy itself.

In case-control studies of ectopic pregnancy, the optimal sampling frame for control selection is influenced heavily by the hypothesis being tested. The selection of women completing an intrauterine pregnancy, a common choice for a control group in studies to date, is appropriate only if the hypothesis does not relate to exposures that selectively prevent an intrauterine pregnancy (e.g., use of an intrauterine device (IUD) at the time of conception). Even for other exposures, the selection of such women can yield misleading results if the exposure is related to the likelihood of completion of the intrauterine pregnancy. On the other hand, the selection of nonpregnant women as controls, while permitting a valid evaluation of the risk associated with exposure such as the use of an IUD, can introduce a substantial degree of incomparability between cases and controls with regard to other contraceptive practices and their correlates. Whichever of the two sampling frames that is chosen, an appreciation of these potential biases can lead to ways of tailoring the selection of individual controls to minimize the magnitude of the bias.

A population-based case-control study was undertaken in 13 counties of western Washington to determine if occupational formaldehyde exposure was related to cancer of the oro- and hypopharynx (OHPC, N = 205), nasopharynx (NPC, N = 27) or sinus and nasal cavity (SNC, N = 53). Controls were selected by random digit dialing (N = 552). A telephone interview inquired about lifetime occupational history as well as a number of potential confounding factors, including smoking and drinking. Approximately half (N = 143) of the case interviews were with next-of-kin. Occupational formaldehyde exposures were assessed by application of job-exposure matrix developed for this study which classified unique job codes into 4 categories based on judgement of likelihood and intensity of formaldehyde exposure. Exposure scores were calculated by weighing the number of years in a formaldehyde-associated job by the assigned exposure level. The effects assuming a 15-year induction period were also investigated. Logistic regression was used to estimate exposure odds ratios (OR) while taking into account multiple risk factors for each site. No significant associations were found between occupational formaldehyde exposure and any of the cancer sites under study. However, relative risk estimates associated with the highest exposure score categories were elevated for OHPC (OR = 1.3, 95% Confidence Interval = 0.6-3.1) and NPC (OR = 2.1, 95% CI = 0.4-10.0) when an induction period was accounted for. When only live interviews were considered, the odds ratios for OHPC and NPC increased to 1.7 and 3.1 respectively. Several limitations in the study tend to conservatively bias the results and must be taken into account in its interpretation.

To examine the relation of regular vigorous exercise to ovulatory infertility, we interviewed 346 infertile women, in whom there was evidence of ovulatory failure, regarding their exercise patterns during the year preceding their unsuccessful effort to conceive. Their responses were compared with similar exercise histories in women who had successfully conceived at the time the infertile women started trying to become pregnant. Vigorous exercise for an hour or more per day was reported more commonly in nulligravid cases (n = 187) than by their primiparous controls. The difference was particularly great in the subgroup of cases without additional evidence of tubal dysfunction (relative risk = 6.2, 90% confidence interval = 1.0 - 39.8). This association was not seen among infertile women who had previously been pregnant. Vigorous exercise for an average of less than one hour per day was not associated with either primary or secondary infertility.

We sought to determine whether women with in situ or invasive squamous cell vulvar cancer were more likely than other women to have had a previous or concurrent tumour at other anogenital sites. One hundred and fifty-eight women with vulvar cancer were identified who were first diagnosed during 1980-1985, were ages 18-79 years at that time, and were residents of one of three counties in western Washington. Two control groups were selected: (1) from records of hospital pathology departments, a sample of 113 women with certain benign conditions of the vulva; (2) through random digit dialing, a sample of 212 women from the general population of these counties. Information on a history of other cancers, and on sexual, reproductive, medical, and demographic characteristics was collected from cases and controls in at-home interviews. Cases were more likely to report a history of other anogenital cancers than were controls, with relative risks of 3.5-29.8, depending on the type of case group and type of control. These associations were not explained by case-control differences in demographic characteristics or frequency of cervical screening. On the other hand, prior or concurrent non-anogenital cancers were equally common in cases and controls. These results support the hypothesis that the different anogenital cancers have at least one aetiology in common.

To determine whether characteristics that are correlated with male homosexual behavior are associated with the incidence of cancer, the names of persons with a diagnosis of cancer in western Washington during 1974 to 1979 were linked to those in the state syphlis registry. Eight of 47 men with anal cancer were found to have had a reactive FTA test result; the expected number, based on the proportion of reactive cases among men with other sites of cancer, was only 0.40. Among men with anal cancer identified through ten population-based cancer-reporting systems in the United States, 24.4% had never been married, compared with 7.8% of men with colon and rectal cancer. Neither of these relationships was observed for women with anal cancer. Because in men, but not in women, having had syphilis and being single are associated with the practice of anal intercourse, our data suggest that anal intercourse may be a risk factor for anal cancer.

The mortality of white female residents of King County (WA) 50-74 yr of age who sustained an isolated fracture of the hip (n = 168) or lower forearm (n = 217) during 1976-79 was monitored during the 2 yr following the fracture. Among the women with hip fracture the (age-adjusted) percentages who died by the end of the first and second year were 5.9 and 10.5%, respectively. Among women with forearm fractures, the corresponding 1- and 2-yr percentages were 1.9 and 2.7%, values similar to that of white women of comparable ages in the population as a whole. The fact that women who broke their hip experienced a higher mortality rate than those who broke their forearm, while women in both groups were similar in having experienced trauma that led to a fracture, argues that it is the hip fracture and its consequences that lead to an increased death rate, rather than the factors that predispose to a fracture.

To determine whether changes in prenatal care utilization and adverse pregnancy outcomes occurred among poor residents of Washington State during the recent recession, we examined all births occurring from 1980 to 1983 to women in the poorest census tracts of the three major metropolitan counties in Washington State (N = 15,735). A comparison sample consisted of all births occurring in the highest income census tracts (N = 16,295). Because the impact of the recession was hypothesized to be greatest in 1982, rates in 1982 were compared with rates in 1980. The proportion of births receiving late or no prenatal care increased in both the low-income tracts (6.2 per cent to 8.2 per cent) and the high-income tracts (1.6 per cent to 2.3 per cent). The proportion of low birthweight infants increased only in the low-income tracts (6.3 per cent to 7.4 per cent). The prevalence of maternal anemia (hematocrit less than 30) also increased only in the low-income tracts (0.7 per cent to 1.7 per cent). While we were unable to ascertain the financial status of the individuals who suffered the adverse outcomes, the findings for the low-income census tracts are consistent with the hypothesis that an increase in adverse pregnancy outcomes occurred among the poor in Washington State during the recent recession.

There is evidence to suggest that breast and thyroid tumors occur together in the same woman more often than would be expected by chance. This study investigates the possibility that various known risk factors for breast cancer also influence the risk of thyroid cancer in women. Female residents of western Washington, in whom papillary, follicular, or mixed thyroid cancer had been diagnosed between 1974 and 1979 (N = 182), were interviewed regarding their medical and reproductive histories. For comparison, a random sample of 389 women from the same population were interviewed. Women who had a history of breast cancer were almost 3 times (95% confidence interval, 0.78-7.9) more likely to develop thyroid cancer than women with no such history. However, a history of breast cancer in a woman's mother did not increase her risk of thyroid cancer. Neither nulliparity, infertility, late age at first full-term pregnancy, early age at menarche, nor a history of abortion or miscarriage before first full-term pregnancy appeared to influence the occurrence of thyroid cancer. Increased weight was associated with an increased risk of thyroid cancer; relative to women who weighed 52 kg or less, those who weighed 60 kg or more had a 2.5-fold elevation in risk. These findings suggest that while cancers of the breast and thyroid are epidemiologically similar in a few ways, there are important differences in a number of their risk factors.

We examined lesions from six women with multifocal neoplasia of the lower genital tract (vulva and cervix or vulva and vagina) for the presence of human papillomavirus (HPV) DNA sequences by DNA-DNA in situ hybridization. Cervical tissue specimens from four of the five women with carcinoma in situ (CIS) of the cervix were found to contain HPV type 16 DNA sequences. Vulvar lesions from three of these women also contained HPV-16 DNA and were histologically consistent with CIS. In each instance, hybridization with HPV-16 DNA probes was seen only in areas of the epithelium that contained evidence of surface maturation or koilocytotic atypia (KA). The HPV DNA was not visualized in regions of these lesions in which the full thickness of the epithelium was occupied by poorly differentiated cells. Virus capsid antigens were only detected in a very few cells in two of the four cervical lesions that contained HPV-16 DNA. HPV type 16, which has consistently been associated with the development of cervical cancer, is further implicated as an agent in the pathogenesis of genital cancers by demonstration of the virus genome in neoplasia at nonadjacent sites.

Serum specimens from 230 sexually active women were tested for antibodies to Chlamydia trachomatis and Chlamydia pneumoniae. The women were randomly selected as controls in a population-based case-control study for ectopic pregnancy. A total of 123 had antibody to C. pneumoniae and 39 had antibody to C. trachomatis. There was an association between prevalence of antibody to C. trachomatis and an increasing number of lifetime sexual partners, early age at first intercourse, and a history of gonorrheal infection. The prevalence of antibody to C. pneumoniae was not related to any of these factors. These results provide evidence that the two human species of Chlamydia have a different mode of transmission and that C. pneumoniae is not sexually transmitted.

Women resident in six counties of Washington and Utah for whom diagnoses of epithelial ovarian cancer were made during 1975-1979 were interviewed concerning their menstrual, reproductive and medical histories. For comparison, interviews were also obtained from a random sample of women living in the same countries. Logistic regression methods were used, and histories of childbearing, miscarriages, lactation, and (in Washington) usage of oral contraceptives were found to be associated with decreased risk of ovarian cancer; the estimated relative risks were, respectively, 0.88 per pregnancy (i.e., 0.88(2) for two pregnancies, etc.) (p = 0.016), 0.82 per miscarriage (p = 0.049), 0.79 per year of lactation (p = 0.034), and 0.89 per year of oral contraception (p = 0.009). In addition, it was observed that the magnitudes of the diminished risks from these exposures substantially exceeded those which would have been expected solely on the basis of their inhibition of ovulation (X2(5) = 21.5, p = 0.0006). On the other hand, the lack of association found between the occurrence of ovarian cancer and either total dose or total time of exposure to noncontraceptive estrogens, or with a history of usage of thyroid medications, suggests that periods of reduced pituitary gonadotrophin secretion fail to reduce risk of ovarian cancer. Thus, although pregnancy, lactation and oral contraception appear to offer some protection against the development of epithelial ovarian cancer, the reasons remain obscure.

We interviewed 327 women who had been 50 to 74 years of age when treated for fracture of the hip of lower forearm, to determine their use (or lack of use) of estrogen preparations. Their responses were compared with those in a random sample of 567 women who were of similar age and from the same region. The risk of fracture was 50 to 60 per cent lower in women who had used these drugs for six years or longer than in women who hadnot used them (95 per cent confidence interval of relative risk, 0.3 to 0.6); those using them for shorter periods received less benefit, if any. A decreased risk of fracture was clearly evident only in women still taking estrogens and evident at either common daily dose (0.625 and 1.25 mg). In conjunction with the finding that estrogens can retard the development of osteoporosis in postmenopausal women, our data argue that lowering of the risk of hip and forearm fractures must be weighed as a benefit of long-term estrogen use.

The relationship between maternal smoking and infant respiratory distress syndrome (RDS) was investigated among 550 premature (36 weeks or less) births delivered at the University of Washington Hospital from 1977 to 1980. Forty-five percent of the mothers were smokers. To avoid bias due to the reduced birth weight of infants of smokers, infants of smokers and nonsmokers were compared within small gestational age categories (two-week intervals) and not by birth weight categories. Infants of mothers who smoked had a reduced incidence of RDS for their gestation compared with infants of nonsmokers. The probability of RDS (adjusted for gestational age and method of delivery) was 25% for the infants of smokers versus 38% for the infants of nonsmokers (odds ratio = 0.55, P = .005), equivalent to approximately a 1.5-week acceleration in lung maturity for infants of smokers. The smoking effect was not explained by demographic differences between smokers and nonsmokers, nor by differences in the incidence of pregnancy complications between the two groups. This study adds support to the theory that adverse pregnancy conditions may lead to an acceleration in pulmonary maturity to allow earlier extrauterine adaptation.

The effect on subsequent pregnancy outcome related to abortion was studied in a sample of 26,000 births in Taiwan. When no adjustment was made for confounding maternal variables, significant relationships were found between previous abortion and various problems of outcome of subsequent pregnancies. However, in a matched-pair cohort study controlling for relevant maternal characteristics, all such relationships disappeared. It is concluded that the deleterious effects of abortion on subsequent pregnancy outcome reported by others may be a consequence of the failure to adjust for maternal factors which are related both to abortion status and pregnancy outcome, and not to abortion itself.

All cases (884) of placental abruption reported on Washington State birth or fetal death certificates in 1980 and 1981 were compared with 789 randomly selected births from the same time period. The incidence of reported cases of placental abruption was 6.5 per 1000 total births. The combined stillbirth and first month death rate of all abruption cases was 21%. Increased risks of placental abruption were associated with pre-eclampsia, diabetes, and unmarried status. Neither parity nor maternal age was associated with an increased risk. Infants born after abruption were significantly smaller-for-gestation than control infants, more likely to be male, and had malformations more frequently than control infants. Apgar scores of liveborn abruption infants were significantly lower than those of controls after adjustment for infant weight, gestational age, and sex.

Data from Washington State birth certificates from 1980-83 were used to estimate excess risk to the infant delivered via repeat cesarean section independently of any risk associated with the indication for the procedure. Using a case-control design, we compared the method of delivery of all infants with low (0-6) five-minute Apgar scores born to multiparous mothers after uncomplicated pregnancies and births to that of similar infants with a high score (7-10), frequency matched by birthweight. Of the 1,030 infants with low Apgar score, 127 (12.3 per cent) were delivered via repeat cesarean section, in contrast to 98 (9.8 per cent) of 998 controls with high Apgar score. In a regression model controlling for birthweight, gestational length, maternal age, and income the relative risk was 1.29 (95% confidence interval 0.97, 1.72). Excess risk was highest among babies of normal (2500-4000 grams) birthweight. While a number of limitations inherent in the source of data require cautious interpretation of these results, we conclude that some excess risk of low Apgar score may be associated with repeat cesarean section procedures.

To determine whether prior oral contraceptive (OC) use is a risk factor for pituitary prolactinoma, we attempted to identify all women (n = 72) with a prolactinoma diagnosed between 1976 and 1980 in three counties in western Washington. A control group of 303 women was selected by dialing random telephone numbers from the same counties. Prior OC use, according to OC indication, was ascertained during a standardized telephone interview. Relative to the risk for women who had never used an OC, the risk of prolactinoma for women who had used OCs for birth control was 1.3 (95% confidence interval, 0.7 to 2.6). This risk was 7.7 for women who used OCs for menstrual regulation (95% confidence interval, 3.7 to 17.0). Previous findings of an association between OC use and prolactinoma may have resulted from OC treatment of menstrual irregularity in women with an undiagnosed prolactinoma.

Previous studies have shown that diabetic women more commonly have complications of pregnancy and adverse infant outcomes than do other women. However, most of the studies have not evaluated women with gestational diabetes separately. The purpose of this study was to evaluate pregnancy complications and infant morbidity and mortality among births to women with gestational diabetes and women with established diabetes. Birth certificate data from 1984 in Washington State linked with death certificate data provided information on complications of pregnancy and infant outcome for 422 gestational diabetics and 144 established diabetics. A comparison group of 856 non-diabetic women who delivered a child was selected at random. Both established and gestational diabetic women were more likely to be reported to develop pre-eclampsia (relative risk (RR) = 4.0 and 9.6). Established and gestational diabetic women were also at increased risk of delivery by Caesarean section (RR = 2.1 and 5.0). Infants of established diabetics had a higher risk of congenital anomalies (RR = 7.6) than infants of non-diabetics and were at increased risk of death in the first 4 weeks (RR = 7.9) and the first year of life (RR = 5.0). Gestational diabetics were more likely to have high birthweight babies (greater than 4000 g) (RR = 2.1) while established diabetics were more likely to have babies at either extreme of birthweight (greater than 4000 g, RR = 1.7; less than 2500 g, RR = 3.2). We conclude that both gestational and established diabetes are associated with important increases in risk of pregnancy complications and adverse infant outcomes.

The medical histories of 105 patients with secondary infertility were studied to determine whether or not induced abortion contributes to the occurrence of secondary infertility. One hundred ninety-nine control cases were matched to these cases according to age, number of previous pregnancies, race, marital status, and socioeconomic status. It was found that women with a history of prior induced abortion did have a sligtly higher risk (risk ratio = 1.31) of secondary infertility, but that the 95% confidence interval (0.71 to 2.43) was consistent with no association at all. When the analysis was restricted to women without ovulatory problems the risk was of similar magnitude. Prior spontaneous abortion was also found to be unrelated to secondary infertility in this series of women.

Methods of delivery, maternal and neonatal characteristics were examined to determine their role in the occurrence of Erb/Duchenne's palsy. Data from 210,947 Washington state birth certificates from 1980 through 1982 were examined. The incidence was 50.2 cases of Erb's palsy per 100,000 live births. A case control study design was used to analyze 106 cases and 386 controls by both univariable and multivariable analysis. Birth weight was shown to be a significant risk factor regardless of which method of delivery was used. A high birth weight infant (4001-4500 g) had 2.5 times the risk of incurring an upper brachial plexus injury compared with normal size infants (2501-4000 g). The risk for infants greater than 4500 g increased another tenfold (OR = 21.0). When birth weight was controlled for in the analysis, midforceps (OR = 18.3), vacuum extraction (OR = 17.2), and low forceps (OR = 3.7) remained significantly associated with the Erb's palsy. Delivery by cesarean section was associated with a significant protective effect (OR = 0.5) compared with instrumental vaginal delivery. These data demonstrate a high risk for serious birth injury associated with instrumental midpelvic delivery.

Abnormalities of cervical mucus can have a bearing on a woman's fertility. One means of detecting the presence of such abnormalities is the postcoital test (PCT). As part of a population-based case control study of risk factors for infertility, the reproductive, contraceptive, medical, and sexual histories of women seeking treatment for infertility who had abnormal PCT results were compared with those of fertile controls. A greater proportion of infertile women with an abnormal PCT had previously used a diaphragm than had control women (relative risk (RR) = 3.5, 95% CI = 1.1-11.3). The excess risk associated with use of a diaphragm was particularly high for women who had used one for longer than one year (RR = 7.3, 95% CI = 1.4-37.8), or within one year of attempting to conceive (RR = 5.5, 95% CT = 1.4-22.1). No increased risk was associated with the use of other barrier methods, oral contraceptives, or the intrauterine device.

A population based case-control study of the association between dissimilar race of parents and risk of pre-eclampsia was undertaken. Data on singleton births in Washington State in 1981 were available for analysis from birth certificates. All mothers recorded as having pre-eclampsia and a sample of mothers who did not have pre-eclampsia were eligible for comparison with regard to racial dissimilarity between parents. Women with previously diagnosed cardiovascular disease and diabetes were excluded. After the confounding effects of maternal parity and race had been controlled for, racial dissimilarity of parents was associated with a 1.9-fold increased risk of pre-eclampsia (95% confidence interval = 1.3-2.8; number of cases = 973, of controls = 1480). This finding supports the theory that genetic dissimilarity of father and mother has a role in pre-eclampsia and is consistent with an immunogenetic aetiology.

To evaluate the association of genital herpes, genital warts, gonorrhea, and trichomoniasis with the occurrence of subsequent tubal infertility, 321 women who had tubal infertility were interviewed concerning their history of these sexually transmitted diseases (STD). The responses were compared to those of women who conceived children during the period the infertile women began trying to become pregnant. By a multivariate analysis, the comparisons were controlled for several confounding variables (e.g., use of an intrauterine device, cigarette smoking, number of prior pregnancies, number of sexual partners, and a history of the other STD). The risk of tubal infertility in women who reported at least one episode of gonorrhea after their last pregnancy, relative to that among other women, was 2.8 (95% confidence interval = 1.3-5.7). The relative risk of tubal infertility was also higher among women who reported a history of trichomoniasis (relative risk = 1.4; 95% confidence interval = 1.0-2.5) or genital warts (relative risk = 1.9; 95% confidence interval = 1.0-3.6).

In a case-control study of thyroid cancer in women in western Washington, the card-back system was used to contact patients. Demographic characteristics and reproductive history of 124 cases who returned a card and 35 who did not were compared, and were found to differ with respect to various reproductive and demographic factors. Relative risk estimates for various thyroid cancer risk factors were calculated two ways: including as cases only those who returned a card, and including all cases; these estimates differed for some risk factors. The results suggest that the use of the card-back system may result in a low level of response which can lead to biased study results.