Laboratory work and pregnancy outcome

Spontaneous abortions among women working in laboratories, and congenital malformations and birth weights of the children were examined in a retrospective case-referent study. In the spontaneous abortion study there were 535 women (206 cases and 329 referents), and in the malformation study 141 women (36 cases and 105 referents). The analysis of the birth weights concerned 500 women (referents). Significant associations with spontaneous abortion were found for exposure to toluene (odds ratio [OR], 4.7, 95% confidence interval [CI], 1.4 to 15.9), xylene (OR 3.1, CI 1.3 to 7.5) and formalin (OR 3.5, CI 1.1 to 11.2) > or = 3 days a week, adjusted for the covariates. Most of the women exposed to formalin and xylene were working in pathology or histology laboratories. No association with congenital malformation was found.     

Unplanned pregnancies in Harare, Zimbabwe: what is the contraceptive history and awareness of the mothers?

OBJECTIVES: The study aimed to estimate the proportion of unplanned pregnancies among mothers delivering at the referral Harare Hospital and to describe their levels of contraceptive use and awareness in relation to the planning of pregnancy. DESIGN: Systematic sample of mothers who had just delivered identified through maternity delivery, records. The study was analysed as a case-referent study where cases where mothers who had unintended pregnancies and those with intended or planned pregnancies served as referents. SETTING: Postnatal wards of Harare Maternity Hospital. SUBJECTS: 923 mothers following delivery. MAIN OUTCOME MEASURES: Socio-demographic characteristics, pregnancy planning, contraceptive history and contraceptive knowledge. RESULTS: Of the 923 deliveries studied, 377 (41%) were unintended (cases), of which 9% were unwanted. Mothers aged 19 years or below (Odds ratio [OR] = 2.4; 95% confidence interval [CI] = 1.6 to 3.7) and those aged 35 years or above (OR = 3.2, 95% CI = 1.8 to 5.5) were significantly more likely to report the index pregnancy as having been unintended. Nulliparous (OR = 2.4) and parity five or more (OR = 8.2) mothers were at significantly increased risk of unintended pregnancy. Mothers presenting with unintended pregnancies were also significantly more likely to be single (OR = 7.8), divorced/separated or widowed (OR = 6.0). Contraceptive ever use was 53% and 58% in cases and referents, respectively. The combined oral contraceptive pill was the most commonly known and used method of contraception. Contraceptive failure was reported by 23% of mothers with unplanned pregnancies. Previous use of the progesterone only pill (OR = 2.2), the condom (OR = 2.3) or the IUCD (OR = 6.3) were significantly associated with the likelihood of reporting with unplanned pregnancy. Mothers in both groups were concerned about contraceptive method failure, irregular menstruation and perceived subsequent infertility with contraception. Failure to discuss family planning with the male partner (OR = 2.3) or partner refusing use of contraception (OR = 2.8) constituted risk factors for unplanned pregnancy. CONCLUSION: Results point to the need for wider contraceptive counselling and provisions which encourage and involve the male partner. Programmes for reproductive health services and education should target women in identified high risk circumstances.     

Uterine artery embolization for the treatment of uterine fibroids

Masking bias is hypothesized to explain associations between breast density and breast cancer risk. Tumours in dense breasts may be concealed at the initial examination, but manifest themselves in later years, suggesting an increase in breast cancer incidence. We studied the association between breast density and breast cancer risk in 0, 1-2, 3-4 and 5-6 year periods between initial examination and diagnosis. We studied 359 cases and 922 referents, identified in a breast cancer screening programme in Nijmegen, The Netherlands. Breast density was assessed at the initial examination and classified as 'dense' (if > 25% of the breast was composed of density) or 'lucent' (< or = 25% density). In women examined with mid-1970s film screen mammography, we found that at time 0 the odds ratio (OR) for women with dense breasts compared to those with lucent breasts was 1.4 (95% confidence interval (CI): 0.7-6.2). After a 3-4 year period the risk was increased to 3.3 (95% CI: 1.5-7.1). Then, the risk decreased again (OR: 1.2, 95% CI: 0.6-2.7). This rise and decline in risk are in accordance with the masking hypothesis. The observation, however, that the risk at time 0 does not appear to be lower for women with dense breasts than for those with lucent breasts, seems to be inconsistent with the masking hypothesis and may be indicative of causality. The same analysis were performed in women whose initial screening examination was done with current high-quality mammography. Due to the small size of this study group no firm conclusions could be drawn, but it seems as if masking bias could still play a role with high-quality mammography.     

Treatment for infertility and risk of invasive epithelial ovarian cancer

The relationship between the use of fertility drugs and the risk of ovarian cancer was analysed using data from an Italian case-control study. The study comprised 971 women below the age of 75 years with histologically confirmed invasive epithelial ovarian cancer diagnosed within the year before the interview. The controls were 2758 women admitted to the same network of hospitals where the cases of ovarian cancer had been identified. Five cases (0.5%) and 11 controls (0.4%) reported use of fertility drugs. In comparison with women who had never used fertility drugs, the multivariate odds ratio (OR) for women who had taken fertility drugs was 1.1 [95% confidence interval (CI) 0.4-3.3]. The OR were 0.7 (95% CI 0.1-7.9) and 1.0 (95% CI 0.2-3.8) for women who had used fertility drugs for <6 and > or =6 cycles respectively. Considering the 14 cases and 45 controls reporting difficulty in conception, the risk of ovarian cancer was 0.5 (95% CI 0.1-3.6) for women who reported use of fertility drugs. Considering nulliparous women only, the estimated OR of ovarian cancer for any fertility drug use was 0.6 (95% CI 0.1-3.5). Although the present results have limitations in terms of statistical power and available information, they provide reassuring evidence of the absence of a strong association between fertility drugs and subsequent risk of developing epithelial ovarian cancer.     

Colonization with vancomycin-resistant enterococci in chronic hemodialysis patients

OBJECTIVE: To identify the prevalence of chorioaminionitis and unique risk factors for this disorder among adolescents under 18 years of age. METHODS: At their first prenatal visit we interviewed 352 adolescents who received prenatal care and delivered an infant at our institution between April 20, 1992, and November 10, 1994, to elicit information on demographic characteristics and behavioral risk factors. Retrospective chart review confirmed the presence of chorioamnionitis using accepted clinical criteria. We determined reproductive history, evidence of sexually transmitted disease, duration of labor, use of oxytocin, an internal uterine pressure monitor or conduction anesthesia, timing and duration of ruptured membranes, type of delivery, and infant birth weight from review of subjects' charts. Logistic regression analysis was used to develop adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for risk factors of chorioaminionitis. RESULTS: Ten percent (34 of 352) of adolescents met the clinical definition for chorioamnionitis. Alcohol and tobacco use during pregnancy (OR 7.6; 95% CI 2.3, 25.8) and being married or living with a partner (OR 2.7; 95% CI 1.1, 6.5) were significantly associated with chorioamnionitis, as was conduction anesthesia (OR 4.1; 95% CI 1.1, 15.4), a second stage labor longer than 2 hours (OR 3.5; 95% CI 1.4, 8.5), and rupture of the membranes longer than 18 hours (OR 6.9; 95% CI 2.5, 18.9). Parity or preterm delivery did not differ significantly between those with or without chorioamnionitis. CONCLUSION: These data suggest that in addition to risk factors observed in adults, adolescents who concurrently use tobacco and alcohol during pregnancy, are married or living with a male partner, and have conduction anesthesia are at increased risk for chorioamnionitis.     

A follow-up program for women with previous gestational diabetes mellitus

OBJECTIVE: To analyse the patterns of attendance in a gestational diabetes mellitus (GDM) follow-up program for detection of impaired glucose tolerance and diabetes mellitus. DESIGN: Retrospective cohort study using computerised data from the GDM follow-up program. PARTICIPANTS AND SETTING: All women with GDM who delivered at the Mercy Hospital for Women in Victoria between 1 January 1981 and 31 December 1995. OUTCOME MEASURES: Enrollment and maintenance in the follow-up program. Predictors of attendance analysed were attendance for the postnatal oral glucose tolerance test (OGTT), severity of GDM, insulin requirement in pregnancy, age at index pregnancy, country of birth, patient booking status and year of index pregnancy. RESULTS: There were 3524 women with GDM delivered during the study period. Attendance for postnatal OGTT was 71% and increased from 43.7% to 69.5% to 84.4% during the three five-year periods of the study (P < 0.00001). Entry into the follow-up program was 58% (1743 of 2986 eligible). A further 538 women (15.3%) were awaiting the postnatal OGTT or first follow-up OGTT. By December 1995, 45% of women who had entered the program had been lost to follow-up. Enrollment in the follow-up program was significantly predicted by insulin requirement in pregnancy (odds ratio [OR], 2.22; 95% confidence interval [95% CI], 1.57-3.13), attendance for postnatal OGTT (OR, 1.94; 95% CI, 1.64-2.29), private patient status (OR, 1.31; 95% CI, 1.12-1.54), severity of GDM (OR, 1.50; 95% CI, 1.24-1.82) and age 30 years or more (OR, 1.37; 95% CI, 1.17-1.60). Maintenance in the follow-up program was significantly associated with attendance for postnatal OGTT (OR, 2.67; 95% CI, 2.19-3.24), insulin requirement in pregnancy (OR, 2.56; 95% CI, 1.87-3.50), age 30 years or more (OR, 1.59; 95% CI, 1.34-1.88) and severity of GDM (OR, 1.55; 95% CI, 1.28-1.89). CONCLUSIONS: There are major difficulties with both recruiting women with GDM into a follow-up program and ensuring their continued attendance. However, a postnatal OGTT and consultation is the most important remediable factor for continuation in a follow-up program. The dedication of the follow-up team administrators rather than the clinical variables of the patients was probably the main determinant of compliance with the follow-up program.     

Aspirin-induced asthma and HLA-DRB1 and HLA-DPB1 genotypes

BACKGROUND: Aspirin-induced asthma (AIA) affects one in 10 individuals with adult-onset asthma. It is not known if aspirin sensitivity is due to immune mechanisms or to interference with biochemical pathways. OBJECTIVE: The study aimed to test for possible involvement of the genes of the Major Histocompatibility Complex (MHC) in AIA. METHODS: HLA-DPB1 and HLA-DRB1 genotyping was carried out by DNA methods in 59 patients with positive challenge tests for AIA and in 48 normal and 57 asthmatic controls. RESULTS: The DPB1*0301 frequency was increased in AIA patients when compared with normal controls (19.5% vs 5.2%, Odds Ratio = 4.4, 95% Confidence Interval (CI) 1.6-12.1, P = 0.002), and compared with asthmatic controls (4.4%, OR = 5.3, 95% CI = 1.9-14.4, P = 0.0001). The frequency of DPB1*0401 in AIA subjects was decreased when compared with normal controls (28.8% vs 49.0%, OR = 0.42, 95% CI = 0.24-0.74, P = 0.003) and asthmatic controls (45.6%, OR = 0.48, 95% CI = 0.28-0.83, P = 0.008). The results remained significant when corrected for multiple comparisons. There were no significant HLA-DRB1 associations with AIA. CONCLUSION: The presence of an HLA association suggests that immune recognition of an unknown antigen may be part of the aetiology of AIA.     

Biologic activity of interleukin 1 (IL-1) alpha in patients with refractory malignancies

To examine the effects of smoking and N-acetylation genetics on breast cancer risk, we analyzed data from an ongoing, population-based, case-control study of invasive breast cancer in North Carolina. The study population consisted of 498 cases and 473 controls, with approximately equal numbers of African-American and white women, and women under the age of 50 and age 50 years or older. Among premenopausal women, there was no association between current smoking [odds ratio (OR), 0.9; 95% confidence interval (CI), 0.5-1.5] or past smoking (OR, 1.0; 95% CI, 0.6-1.6) and breast cancer risk. Among postmenopausal women, there was also no association with current smoking (OR, 1.2; 95% CI, 0.7-2.0); however, a small increase in risk was observed for past smoking (OR, 1.5; 95% CI, 1.0-2.4). For postmenopausal women who smoked in the past, ORs and 95% CIs were 3.4 (1.4-8.1) for smoking within the past 3 years, 3.0 (1.3-6.7) for smoking 4-9 years ago, and 0.6 (0.3-1.4) for smoking 10-19 years ago. Neither N-acetyltransferase 1 (NAT1) nor N-acetyltransferase 2 (NAT2) genotype alone was associated with increased breast cancer risk. There was little evidence for modification of smoking effects according to genotype, except among postmenopausal women. Among postmenopausal women, ORs for smoking within the past 3 years were greater for women with the NAT1*10 genotype (OR, 9.0; 95% CI, 1.9-41.8) than NAT1-non*10 (OR, 2.5; 95% CI, 0.9-7.2) and greater for NAT2-rapid genotype (OR, 7.4; 95% CI, 1.6-32.6) than NAT2-slow (OR, 2.8; 95% CI, 0.4-8.0). Future studies of NAT genotypes and breast cancer should investigate the effects of environmental tobacco smoke, diet, and other exposures.     

History of lactation and breast cancer risk

A self-administered questionnaire was completed by 1,018 women diagnosed with breast cancer during 1988-1989 identified through the British Columbia Cancer Registry and by 1,025 controls selected at random from the Provincial Voters List. Parous premenopausal women who had never nursed (odds ratio (OR) = 1.3, 95% confidence interval (CI) 0.9-2.0) or who had lactated for 1 month or less (OR = 1.8, 95% CI 1.3-2.5) had an increased risk of breast cancer adjusted for age and parity, compared with women who had breast-fed 2 months or longer. The risk was particularly elevated (OR = 3.0, 95% CI 1.6-5.4) among women who reported having tried to nurse, but who were unsuccessful. Among women who nursed for at least 2 months, there was an indication of decreasing risk with increasing duration of nursing. Among postmenopausal parous women, no relation between lactation history and breast cancer risk was evident.     

The association of calcium and vitamin D, and colon and rectal cancer in Wisconsin women

BACKGROUND: Calcium and vitamin D have been hypothesized to reduce colorectal cancer risk. Epidemiological evidence, however, is mixed. METHODS: To explore those relationships, data were collected as part of a population-based, case-control study of colorectal cancer in Wisconsin women (678 controls, 348 colon and 164 rectal cancer cases). A semi-quantitative food frequency questionnaire was used to ascertain food and dietary supplement intake 2 years prior to interview. Logistic regression models were used to calculate odds ratios (OR). RESULTS: Higher levels of calcium intake were associated with reduced colon and rectal cancer risk. The following adjusted OR and 95% confidence intervals (CI) were observed, comparing the fifth quintile (based on control intake) with the first: colon cancer: OR = 0.6, 95% CI: 0.4-1.0, P-trend: 0.03; rectal cancer: OR = 0.6, 95% CI: 0.3-1.1, P-trend: 0.07. Similar relationships were observed for vitamin D intake, although OR were closer to the null value and did not always behave in a step-wise fashion (fifth quintile versus the first--colon cancer: OR = 0.7, 95% CI: 0.4-1.1, P-trend: 0.05; rectal cancer: OR = 0.8, 95% CI: 0.5-1.5, P-trend: 0.42). CONCLUSION: These data support a protective association of calcium on colon and rectal cancer risk.     

Degradation of weathered oil by mixed marine bacteria and the toxicity of accumulated water-soluble material to two marine crustacea

From 1982 to 1984, the authors conducted a population-based case-control study of lung cancer in men and women nonsmokers in New York State. In-person interviews were completed for 437 lung cancer cases (197 never smokers, 240 former smokers) and 437 matched population controls. Cases and controls were asked to report any history of physician-diagnosed nonmalignant lung disease; cases were more likely than controls to report such a history. Statistically significant associations were found for emphysema (odds ratio (OR) = 1.94, 95% confidence interval (CI) 1.10-3.43), chronic bronchitis (OR = 1.73, 95% CI 1.10-2.72), and the combined endpoint of emphysema, chronic bronchitis, or asthma (OR = 1.82, 95% CI 1.26-2.63). After adjustment for active and passive tobacco smoke exposure, emphysema, chronic bronchitis, and asthma (each condition and the combined endpoint) were significantly associated with lung cancer risk. The risk was more marked for squamous cell carcinomas and for subjects who were diagnosed at older ages, and it remained significant when surrogate interviews were excluded. These results are consistent with the hypothesis that certain prior lung conditions increase the risk of lung cancer in men and women nonsmokers.     

Symptom-related self-care of Mexican Americans with type 2 diabetes: preliminary findings of the Starr County Diabetes Education Study

OBJECTIVES: Late age at first birth and nulliparity are established risk factors for breast cancer, yet the extent to which fertility problems contribute to these associations remains largely unexplored. Here, we examine self-reported fertility problems as a risk factor for breast cancer in young women. METHODS: We used a population-based case-control study of 2,173 cases and 1,990 controls aged 20 to 54 years in the United States. Structured in-person interviews were used to elicit detailed information on established and potential breast cancer risk factors. Information was collected on pregnancy details, including difficulties becoming pregnant or maintaining a pregnancy. RESULTS: Self-reported difficulty in becoming pregnant or maintaining a pregnancy was reported by 450 cases and 377 controls. Overall, there was little association between these fertility problems and risk of breast cancer (odds ratio [OR] = 1.05). Parity was associated with a decreased risk of breast cancer in women both with (OR = 0.71) and without (OR = 0.79) fertility problems. There was little evidence of an increased risk of breast cancer with later age at first full-term birth among women without fertility problems (ORage 35+ :age <20 = 1.13, 95 percent confidence interval [CI] = 0.7-1.9), but a relatively strong association among women with fertility problems (ORage 35+ :age <20 = 2.96, CI = 1.3-7.0). Among women with a first full-term birth at age 35 or older, fertility problems were associated with a twofold risk of breast cancer. Analyses of duration of unprotected sexual intercourse prior to first pregnancy as an alternative estimate of infertility produced similar results. CONCLUSIONS: Our study suggests that the association between late age at first birth and breast cancer is stronger among women with self-reported fertility problems than among women with no fertility problems.     

Metals pollution in marine sediments of the United Arab Emirates creeks along the Arabian Gulf shoreline

In order to evaluate the association between seropositivity for herpes simplex virus (type 1 and type 2) and cervical intraepithelial neoplacia (CIN), we analysed data from a population-based case-control study of CIN grade II-III which included Norwegian women aged 20 to 44 years, 94 cases and 228 controls. Our objectives were to determine if HSV-1 and/or HSV-2 seropositivity were independent risk factors for CIN, taking human papillomavirus exposure into account, and to elucidate the combined effect of HPV positivity and seropositivity for HSV In logistic regression analyses, the association between HSV-2 or HSV-1 seropositivity and CIN II-III was not explained by HPV (adjusted OR 3.0; 95%, CI 1.3-7.2 and adjusted OR 3.3; 95% CI 1.3-8.4, respectively). In analyses restricted to HPV-16 DNA-positive individuals, seropositivity for HSV-2 increased the risk of CIN (OR 11.1; 95% CI 1.2-105.7), whereas HSV-1 seropositivity was not significantly associated with CIN. In women positive for other HPV types, only HSV-1 seropositivity was associated with CIN (OR 8.5; 95% CI 1.3-55.8). In analyses of the HPV-16-seropositive individuals, neither HSV-1 nor HSV-2 seropositivity was associated with CIN. Compared to the reference group of jointly unexposed subjects, the HPV-16 DNA-positive women who were anti-HSV-2 negative had an increased risk of CIN (OR 29; 95% CI 12-67), whereas the risk in women who were both HPV-16 DNA-positive and HSV-2 was OR=247 (95% CI 31-1996). The estimate of interaction was strong, but did not reach significance, and our findings may suggest that the combined effect of the two viruses is of aetiological importance in cervical carcinogenesis. Furthermore, the results indicate that HPV DNA positivity is not sufficient to explain the sexual behaviour-associated risk of cervical neoplasia and that further studies on the role of genital HSV (type 1 as well as type 2) and other STDs are warranted.     

Factor V Leiden, C > T MTHFR polymorphism and genetic susceptibility to preeclampsia

We performed a case-controlled study to investigate whether the FV Leiden mutation and the C > T677 polymorphism of the 5, 10 methylene tetrahydrofolate reductase (MTHFR) are associated with the occurrence of preeclampsia in 96 otherwise healthy preeclamptic women and 129 parous women as controls. FV Leiden carriers were 10 (10.5%) in cases and 3 (2.3%) in controls (OR: 4.9, 95% CI: 1.3-18.3). MTHFR TT homozygotes were 28 (29.8%) in cases and 24 (18.6%) in the control group (OR: 1.8, 95% CI 1.0-3.5). No difference in any of the polymorphisms was found between proteinuric (n = 45) and non-proteinuric (n = 51) patients. Moreover, MTHFR polymorphism does not affect the association between FV Leiden and preeclampsia. In conclusion, FV Leiden mutation and MTHFR TT genotype are associated with the occurrence of preeclampsia, suggesting that, during pregnancy, women carrying these gene variants are prone to develop such a complication.     

Alcohol consumption and risk of breast cancer: a multicentre Italian case-control study

The relationship between alcohol consumption and breast cancer risk was investigated using data from a co-operative case-control study conducted in Italy between 1991 and 1994 on 2569 incident, histologically confirmed breast cancer cases and 2588 controls in hospital for acute, non-neoplastic, non-hormone related conditions. Overall, 915 (38%) cases and 1048 (43%) controls were abstainers. Compared with them, the odds ratio (OR), adjusted only for age, was 1.31 (95% confidence interval (CI) 1.13-1.53) for drinkers and became 1.39 (95% CI 1.(1)21-1.60) after correction for measurement error. The multivariate OR was 1.21 for drinkers of < or = 5.87 g/day and 1.23, 1.19, 1.21, 1.41 for drinkers of 5.88-13.40, 13.41-24.55, 24.56-27.60, > 27.60 g/day, respectively. The trend in risk was significant (chi 2 = 12.28, P < 0.0005). The association was apparently stronger in premenopausal women (OR = 1.80 for > 27.60 g/day). Considering the different types of alcoholic beverages (wine, beer, digestives, grappa and other spirits), a significant direct trend in breast cancer risk was seen for wine with an OR of 1.27 (95% CI 1.06-1.53) for the category > 26.34 g/day. The ORs were also above unity for beer, grappa, digestives and spirits drinkers. No appreciable interaction was observed between alcohol drinking and body mass index, smoking, or any other covariate considered. Thus, the present data, based on a validated alcohol consumption questionnaire and on a population characterised by a relatively high alcohol consumption in women, confirmed that alcohol drinking is moderately related to breast cancer risk. If causal, this association could explain 12% (95% CI, 5-19%) of breast cancers in Italy, thus representing one of the major avoidable risk factor for breast cancer.     

Relationship between abortions and seroprevalences to selected infectious agents in dairy cows

The aim of this study was to determine whether the occurrence of abortion is related to the seroprevalence of abortion-causing infectious agents. In a cross-sectional study, cattle from dairy farms in Switzerland that were defined as having an abortion problem were divided into two groups: cows with a history of abortion within the previous 3 months (cases) and cows without a history of abortion (controls). A positive titre to Leptospira spp. was associated with an increased probability of being a case (OR = 1.74, 95% CI = 1.21-2.47). There were interactions between Coxiella burnetti titre and parity, and between Chlamydia psittaci and C. burnetti titre and breed. Multiparous cases after the second lactation with a positive titre to C. burnetti were less likely (OR = 0.42, 95% CI = 0.22-0.82) to be cases. Swiss Browns (Swiss Braunvieh and Brown Swiss) with a positive titre to C. psittaci and Swiss Browns with a positive titre to C. burnetti were more likely (OR = 1.63, 95% CI = 1.13-2.37 and OR = 1.79, 95% CI = 1.15-2.78, respectively) to be cases. Parity alone was not associated with the occurrence of abortion.     

Epidemiologic determinants of endometriosis: a hospital-based case-control study

PURPOSE: Risk factors for endometriosis were identified through data obtained from a case-control study at Brigham and Women's Hospital in Boston, Massachusetts. METHODS: Cases were 50 women with infertility-associated endometriosis. The primary control group consisted of 89 fertile women without endometriosis, and an alternate control group consisted of 47 infertile women without endometriosis. RESULTS: The risk of endometriosis was positively associated with height (OR), 2.8 per 10 cam increase; 95% confidence interval (CI), 1.4-5.6) and inversely associated with weight (OR, 0.7 per 10 kg increase; 95% CI, 0.5-1.0) and body mass index (OR, 0.7 per 5 kg/m2 increase; 95% CI, 0.4-1.1). We observed an inverse association with exercise (OR, 0.6; 95% CI, 0.3-1.5), but the effect was limited to women who exercised > or = 4 hours per week (OR, 0.4; 95% CI, 0.2-1.2). Endometriosis was not associated with either smoking or alcohol consumption. CONCLUSIONS: Our findings suggest that the fertility status of controls can strongly influence associations seen with menstrual characteristics. This study is one of few to address the issue of control selection for a case-control study of endometriosis. Specifically, potential problems encountered using fertile and infertile control women are examined and discussed.     

A general practice case-control study of delayed immunisation in under two year old children

AIM: To identify social factors which characterise the household of children with delayed immunisation. METHOD: The study was done in 15 general practices in the Wellington city region with a case-control design where preschool children who were not up to date (cases) for their immunisations were compared with children who were up to date (controls). RESULTS: There were 215 cases where immunisation was delayed among 3723 children at the time of audit in June 1996. Ethnic status was available from general practice records in 33% of cases and 40% of controls. There were more Maori and Pacific Island children among the cases compared to controls (39% versus 21%, odds ratio (OR) = 2.39, 95% confidence interval (CI) 1.12-5.10, p = 0.022. CASE SAMPLE HOUSEHOLDS COMPARED WITH CONTROLS HAD: (1) more children in the households (mean 2.27 versus 1.98, p = 0.01); (2) more households with a female as the only adult (35% versus 24%, OR = 1.61, 95% CI 1.04-2.51, p = 0.034). There was no difference in the proportions of male only adults (0.02% versus 0.01%, p = 0.70); (3) more mothers who were under 30 years of age (38% versus 25%, OR = 1.61, 95% CI 1.04-2.51, p = 0.034); and more fathers under 30 years of age (20% versus 10%, OR = 2.16, 95% CI 0.97-4.84, p = 0.06); (4) fewer mothers who were up to date with their recorded cervical smear status (66% versus 83%, OR = 0.69, 95% CI 0.23-0.63, p < 0.001); (5) more parents with an active community services card (38% versus 25%, OR 1.82, 95% CI 1.17-2.82, p = 0.007); (6) fewer siblings being immunised (70% versus 94%, OR = 0.14, 95% CI 0.07-0.28, p < 0.001). CONCLUSION: There is a distinct group of New Zealand children for whom immunisation is delayed. Such children live in households which can be characterised by various social factors easily obtainable from general practice records. The identified households could be targeted for efficient preventive care by general practices.     

Cellular glutathione peroxidase is the mediator of body selenium to protect against paraquat lethality in transgenic mice

A case-control study was conducted between 1992 and 1996 in six Italian areas. It included 537 women with colon cancer, 291 women with rectal cancer and 2081 control women in hospital for acute conditions, unrelated to hormonal or gynaecological diseases. A higher age at menopause was associated with increased colon cancer risk (odds ratio (OR) for > or = 53 years compared with < 50 years = 1.39, 95% confidence interval (CI) 1.04-1.87). Among parous women, a significant trend of decreasing colon cancer risk with increasing number of births was seen for colon (OR for > or = 4 births compared with 1 birth = 0.62, 95% CI 0.42-0.90), but not for rectal cancer. Nulliparous women, however, were at lower risk than women with a single birth, and age at first birth was directly associated with risk. While oral contraceptive use showed no significant influence, ever users of hormone replacement therapy had a reduced risk of rectal cancer (OR = 0.56, 95% CI 0.31-1.01). Thus, the association of colorectal cancer with reproductive and menstrual factors is neither strong nor consistent.