The relation between multiple births and maternal risk of breast cancer.

Data from two case-control studies conducted in New York State during 1982-1986 were used to examine the relation between multiple births and the maternal risk of breast cancer. The cases were 2,561 women between 20 and 79 years of age with a diagnosis of primary breast cancer. Controls (n = 2,616) were selected from driver's license files and matched to cases by year of birth and county of residence. The odds ratio for any multiple birth was 0.94 (95% confidence interval (CI) 0.56-1.56) in women less than 55 years of age and 0.95 (95% CI 0.62-1.46) in women aged 55-79 years. A previous study had shown a multiple last birth to be protective against breast cancer in women less than 55 years of age (odds ratio (OR) = 0.60, 95% CI 0.43-0.85). A decreased risk of breast cancer was also observed for this age group in the present study, but the magnitude of the effect was not as strong and the confidence interval included unity (OR = 0.85, 95% CI 0.43-1.68). A logistic model that controlled for age at first pregnancy, number of live births, age, and county of residence increased the odds ratio to 0.97 for a multiple last birth. The current study does not support an association between multiple births and maternal risk of breast cancer.     

Perinatal and maternal risk factors for autism spectrum disorders in New South Wales, Australia

Background This study was commenced in 1999 with the aim of examining risk factors for autism using established population‐based data for comparison. Methods Cases were ascertained using active surveillance and compared with birth data. Results Four risk factors were found to be significantly associated with autism using binary logistic regression analysis; being male [adjusted odds ratio (OR) 4.7, 95% confidence interval (CI) 3.2–7.0], being born prematurely (adjusted OR 2.2, 95% CI 1.5–3.5), having maternal age ≥35 years (adjusted OR 1.7, 95% CI 1.2–2.4) and having a mother born outside Australia (adjusted OR 1.4, 95% CI 1.0–1.9). For analysis completed for pregnancies, rather than live births, multiple birth was also a significant risk factor for one or more children of the pregnancy to be affected by autism (adjusted OR 2.5, 95% CI 1.1–5.5). There was a statistically significant trend towards increasing risk with increasing risk factor ‘dose’ for gestational age (P = 0.019), multiple birth (P = 0.016) and maternal age (P < 0.001). For mother's country of birth the group with the highest risk were children of mother's born in south‐east or north‐east Asia. There was a non‐significant trend towards a higher proportion of children with developmental disability having risk factors. Conclusion Replication of risk factors from previous studies and a significant risk factor ‘dose’ effect add to growing evidence that maternal and perinatal factors are low magnitude risk factors for autism. The association between developmental disability and autism risk factors warrants further examination.     

中国六城市女性生理生育因素与乳腺癌关系的病例对照研究

目的研究城市女性乳腺癌的危险因素,探讨城市女性生理生育因素的变化与城市女性乳腺癌发病的关联强度,促进乳腺癌的预防和控制。方法采用病例对照的研究方法,新发病例通过北京、天津、上海、重庆、武汉、广州六城市的乳腺癌监测点确定,对照从当地正常人群数据库中随机抽样,对收集到3332对1：1年龄配对的病例和对照进行问卷调查。通过条件Logistic模型进行相对危险度及剂量-反应效应估计。结果在调整年龄、职业、饮食等因素后,城市女性中乳腺癌发病的危险因素为初潮年龄的提前（≤14岁,OR=1.37,95％CI=1.12－1.66）、月经持续天数长（〉7天,OR=1.18,95％ CI=1.00－1.38）、有痛经（OR=1.21,95％ CI=1.03－1.42）、结婚晚（≥28岁,OR：2.13,95％ CI=1.63－2.79）、首次怀孕晚（≥30岁,OR=2.13,95％CI=1.63－2.79）等,而保护性因素有月经间隔天数长（ 〉28天,OR=0.81,95％ CI=0.68－0.95）、绝经年龄早（≤45岁,OR=0.58,95％ CI=0.47－0.72）、怀孕次数多（≥2次,OR=0.67,95％ CI=0.45－0.99）,哺乳（≥4个月,OR=0.70,95％CI：0.60－0.83）。结论女性生理生育因素是影响城市女性乳腺癌发病的主要危险因素,可部分解释中国城市女性乳腺癌呈逐年上升趋势的原因。     

Maternal ethnicity and pre-eclampsia in New York City, 1995-2003

Studies on ethnic differences in the risk of pre-eclampsia are limited. We linked birth records for 902,460 singleton births for the period 1995-2003 in New York City with hospital discharge data to evaluate the association between ethnicity and the risk of pre-eclampsia and compare risks between US-born and foreign-born women. Logistic regression models adjusted for maternal age, maternal education, parity, self-reported pre-pregnancy maternal weight, smoking during pregnancy and year of delivery were used to compare each ethnic group with non-Hispanic White women. The prevalence of pre-eclampsia in this study population was 3.2%. Among the major ethnic groups considered in our study, East Asian women had the lowest risk of pre-eclampsia (1.4%) and Mexican women had the highest risk (5.0%). Compared with non-Hispanic White women, there was a slightly decreased risk for East Asian women (adjusted OR = 0.8, [95% CI 0.7, 0.8]), similar risk for North African women (adjusted OR = 1.1, [95% CI 0.9, 1.3]), and increased risk for all other major ethnic groups (adjusted ORs: 1.3, 2.9), with the highest risk for Mexican women (adjusted OR = 2.9, [95% CI 2.7, 3.1]). No difference in risks was observed for US- vs. foreign-born women with the exception that foreign-born South-East Asian and Pacific Islanders had an increased risk of pre-eclampsia (adjusted OR = 1.8, [95% CI 1.0, 3.1]) relative to those born in the US. We concluded that there was ethnic heterogeneity in the development of pre-eclampsia among women in New York City and that Asian subgroups should be examined separately in future studies on ethnicity. Our results should contribute to screening for pre-eclampsia taking ethnic variation into account, and may help to suggest leads for the study of the aetiology of the condition.     

Maternal risk of breast cancer and birth characteristics of offspring by time since birth.

We examined the association between birth characteristics of offspring and the subsequent maternal risk of breast cancer in a population-based cohort of 998,499 women, 13 to 48 years of age at entry. There were 9,495 incident cases of breast cancer during 12.8 million person-years of follow-up among these women. Compared with mothers of singleton infants, mothers having a multiple birth had an increased risk of breast cancer in the first 5 years after a birth (relative risk (RR) = 1.8; 95% confidence interval (CI) = 1.1-2.8). The risk for mothers having a heavy-weighted child (>3.75 kg), as compared with a child of light weight (< or =3 kg), was also slightly increased (RR = 1.2; 95% CI = 0.9-1.5). This latter effect was primarily due to an increased incidence of tumors larger than 2 cm at diagnosis (RR = 1.4; 95% CI = 0.9-1.9). Our findings are compatible with the hypothesis that the hormonal level during pregnancy influences the risk of breast cancer in the early years after delivery.     

Relations of gestational length and timing and type of incomplete pregnancy to ovarian cancer risk

While the protective nature of parity with respect to ovarian cancer has been well documented, whether a history of incomplete pregnancy affects ovarian cancer risk is uncertain. Data collected from 739 epithelial ovarian cancer cases and 1,313 community controls in the Delaware Valley from 1994 to 1998 were used to evaluate the relation between gestational length and timing of first induced or spontaneous abortion and ovarian cancer risk. Incomplete pregnancy was not associated with ovarian cancer among nulliparous women or among ever-pregnant women either before or after adjustment for relevant confounders (for nulliparous women, odds ratio (OR) = 1.12, 95% confidence interval (CI): 0.66, 1.89; for ever-pregnant women, OR = 0.95, 95% CI: 0.76, 1.18). Among unigravid women, one full-term pregnancy was more protective than an incomplete pregnancy (adjusted OR = 0.29, 95% CI: 0.15, 0.57). These results were independent of the type of pregnancy loss. Among ever-pregnant women, a spontaneous abortion before a first birth provided significant protection (adjusted OR = 0.47, 95% CI: 0.30, 0.75), while no significant effect was found for an induced abortion prior to a first birth (adjusted OR = 0.80, 95% CI: 0.44, 1.47). These data do not support an independent association between incomplete pregnancies, either spontaneous or induced, and ovarian cancer risk.     

Perinatal mortality associated factors in a general hospital of Chiapas, Mexico

OBJECTIVE: To identify socioeconomic, gynecological-obstetric and fetal factors associated with perinatal mortality. METHODS: A matched case-control study was carried out. Cases were newborns (born live or dead) that were born and died between 28 weeks gestation and 7 days of life. Controls were live newborns between 28 weeks gestation and 7 days of life. A total of 99 cases and 197 controls were studied. Data were obtained from the corresponding medical charts. Statistical analysis was performed using Stata 6.0 software. RESULTS: Mean maternal age was 24.82 years and mean newborn age was 37.78 weeks gestation with an average birth weight of 2,760 grams. Factors associated with perinatal mortality were: father's occupation as a farmer (adjusted odds ratio (OR)=3.31; 95% CI=1.26-8.66); high obstetric risk index (adjusted OR=10.57; 95% CI=2.82-39.66), cesarean birth (adjusted OR=2.75; 95% CI=1.37-5.51), five or more prenatal visits (adjusted OR=4.43; 95% CI=1.86-10.54) and preterm fetal maturity indices (PEG, APG, GEG) (adjusted OR=9.20; 95% CI=4.39-19.25). CONCLUSIONS: The risk factors associated with perinatal mortality found in the study are consistent with the findings reported in the international literature. These results show that prevention and control measures should be implemented to identify at risk pregnant women in order to lower perinatal mortality.     

Postmenopausal estrogen use and invasive versus in situ breast cancer risk

To examine the effect of cancer histopathology on the relationship between estrogen-replacement therapy (ERT) use and breast cancer risk, we performed a case-control study of 109 postmenopausal women 45 years or older with in situ or invasive breast cancer matched to 545 controls. When in situ and invasive tumors were combined, the overall odds ratio (OR) describing the association between ERT use and breast cancer risk was not statistically significantly elevated (adjusted OR = 1.48, 95% confidence interval [CI] = 0.89–2.47). When the analyses were confined to women with invasive disease, risk estimates were uniformly higher (adjusted OR = 1.85, 95% CI = 1.00–3.45). In contrast, the overall estimate for the relationship between ERT use and in situ breast cancer was close to 1 (adjusted OR = 1.08, 95% CI = 0.42–2.77). The positive association between ERT use and invasive breast cancer we observed, and the lack of association in women with in situ disease, may represent a distinct biological difference or may be related to the small sample size of our study.     

Postmenopausal Estrogen Use and Invasive versus in situ Breast Cancer Risk

To examine the effect of cancer histopathology on the relationship between estrogen-replacement therapy (ERT) use and breast cancer risk, we performed a case-control study of 109 postmenopausal women 45 years or older with in situ or invasive breast cancer matched to 545 controls. When in situ and invasive tumors were combined, the overall odds ratio (OR) describing the association between ERT use and breast cancer risk was not statistically significantly elevated (adjusted OR = 1.48, 95% confidence interval [CI] = 0.89–2.47). When the analyses were confined to women with invasive disease, risk estimates were uniformly higher (adjusted OR = 1.85, 95% CI = 1.00–3.45). In contrast, the overall estimate for the relationship between ERT use and in situ breast cancer was close to 1 (adjusted OR = 1.08, 95% CI = 0.42–2.77). The positive association between ERT use and invasive breast cancer we observed, and the lack of association in women with in situ disease, may represent a distinct biological difference or may be related to the small sample size of our study.     

Maternal age, exposure to siblings, and risk of amyotrophic lateral sclerosis

Between 1987 and 2005, the authors conducted a nested case-control study based on the Swedish Multi-Generation Register to investigate whether early life exposures, namely, maternal age at delivery and exposure to siblings, are associated with an increased risk of amyotrophic lateral sclerosis (ALS). The study comprised 768 ALS cases and five controls per case matched by birth year and gender. Odds ratios and their corresponding 95% confidence intervals for ALS were estimated by conditional logistic regression modeling. Low maternal age (< or =20 years) and high maternal age (> or =41 years) were both associated with higher risk of ALS (odds ratio (OR) = 1.5, 95% confidence interval (CI): 1.1, 2.0 and OR = 1.7, 95% CI: 1.1, 2.4, respectively). The relative risk of ALS increased slightly with increasing number of younger siblings (OR = 1.1, 95% CI: 1.0, 1.1; p = 0.02). Children whose first younger sibling was born after the age of 6 years had the greatest relative risk (OR = 1.8, 95% CI: 1.2, 2.7). Exposure to older siblings was not associated with the risk of ALS. Although the strength of the observed associations was modest, these results provided further support for the theory that early life exposures might contribute to the disease pathogenesis.     

Childhood growth and breast cancer

Adult height is known to be positively associated with breast cancer risk. The mechanism underlying this association is complex, since adult height is positively correlated with age at menarche, which in turn is negatively associated with breast cancer risk. The authors used prospective data from a British cohort of 2,547 girls followed from birth in 1946 to the end of 1999 to examine breast cancer risk in relation to childhood growth. As expected, adult height was positively associated with age at menarche and breast cancer. In childhood, cases were taller and leaner, on average, than noncases. Significant predictors of breast cancer risk in models containing all components of growth were height velocity at age 4-7 years (for a one-standard-deviation increase, odds ratio (OR) = 1.54, 95% confidence interval (CI): 1.13, 2.09) and age 11-15 years (OR = 1.29, 95% CI: 0.97, 1.71) and body mass index velocity (weight (kg)/height (m)(2)/year) at age 2-4 years (OR = 0.63, 95% CI: 0.48, 0.83). The effects of these variables were particularly marked in women with early menarche (age <12.5 years). These findings suggest that women who grow faster in childhood and reach an adult height above the average for their menarche category are at particularly increased risk of breast cancer.     

Cigarette smoking and breast cancer.

An epidemiological case-control study was conducted in New York State, with 1617 primary breast cancer patients and an equal number of controls, to examine the relationship between cigarette smoking and breast cancer. Results showed no overall association between ever smokers versus never smokers and breast cancer risk (odds ratio [OR] = 1.03, 95% confidence interval [CI]: 0.90-1.19), nor was there any dose response trend observed with increased levels of smoking. In addition, no association was found with risk and age started smoking, age stopped smoking, amount smoked or total years smoked. Controlling for previously identified risk factors for breast cancer in the analysis did not significantly alter these relationships. Previous studies have found a difference in menopausal age among smokers compared to nonsmokers. The mean menopausal age was only slightly lower in smokers than in never smokers for both cases and controls. Breast cancer risk was observed to be close to unity for premenopausal women (OR = 0.97, 95% CI: 0.74-1.34) and postmenopausal women (OR = 1.06, 95% CI: 0.91-1.26). A recent study suggested breast cancer risk was more strongly related to starting smoking at a young age among women who smoked at least 25 or more cigarettes per day in the most recent year of smoking. This hypothesis was not supported by these data.     

Fruits, vegetables, soy foods and breast cancer in pre- and postmenopausal Korean women: a case-control study

We carried out a case-control study to examine the relationship between fruits, vegetables, and soy foods intake with breast cancer risk in Korean women. Incident cases (n = 359) were identified through cancer biopsies and hospital-based controls (n = 708) were selected in the same hospitals. Subjects were asked to indicate usual dietary habits, which were assessed using a semi-quantitative food frequency questionnaire (98 items). Odds ratio (OR) and 95% confidence intervals (95% CI) were calculated by unconditional logistic regression after adjustment for additional confounding factors according to the menopausal status. High grape intake showed an inverse association of breast cancer in postmenopausal women (OR = 0.59, 95% CI = 0.35-0.95; p for trend = 0.05). High tomato intake was associated with reduced breast cancer risk in premenopausal women (OR = 0.59, 95% CI = 0.38-0.89, p for trend = 0.04). In postmenopausal women, green pepper intake showed an inverse association of breast cancer risk (OR = 0.60, 95% CI = 0.43-0.96, p for trend = 0.03). High soybean intake showed an inverse association of breast cancer in postmenopausal women (OR = 0.61, 95% CI = 0.34-0.89, p for trend = 0.02). Our study suggests that high intake of some fruits, vegetables, and soybeans may be associated with a reduced breast cancer risk.     

Lifetime alcohol consumption and postmenopausal breast cancer rate in Denmark: a prospective cohort study

Alcohol intake may be one of the few modifiable risk factors for breast cancer. In a prospective cohort of 29,875 women with 423 cases of breast cancer during 1993-2000, we examined the relationship between postmenopausal breast cancer incidence rate and alcohol consumption in different life periods. When alcohol intake during four age ranges, twenties, thirties, forties and fifties was evaluated, only the intake in the fifties increased the risk of breast cancer [rate ratio (RR)=1.12 (95% CI: 1.05-1.19)] per 10 g/d increase in alcohol intake. After adjustment for intake at study entry, this association was no longer present [RR=1.01 (95% CI: 0.91-1.13)]. The cumulative lifetime alcohol intake, adjusted for recent intake, showed no association with postmenopausal breast cancer risk. Recent alcohol intake, adjusted for the alcohol intake in the other life time periods, showed a significant association of RR=1.09 (95% CI: 1.00-1.18) per 10 g/d. There was no indication of a higher risk among women with early drinking start, nor did women who started to drink before their first birth have a higher risk than women who started to drink later in life. Our results suggest that baseline intake of alcohol is a more important determinant of postmenopausal breast cancer risk than earlier lifetime exposure.     

The influence of maternal age on very preterm birth of twins: differential effects by parity

For singleton births, parity can modify the effect of maternal age on birth outcomes such as low birthweight and preterm birth; however, it is unknown whether this relationship exists for twin births. As the rate of twin births increases among older women, it is important to understand how parity may influence the relationship between maternal age and adverse birth outcomes. The NCHS Matched Multiple Birth Data Set, which contains all twin births in the USA from 1995 to 1998, was analysed. Parity was grouped into two levels (primiparous--no prior live births, and multiparous--at least one prior live birth), and maternal age was divided into the following groups: 20-24, 25-29, 30-34, 35-39, and 40 years or more. Very preterm birth was defined as births occurring before 33 weeks. Logistic regression was used to obtain odds ratios (OR) to estimate the risk of very preterm birth, and to determine the relationships between parity, maternal age, and very preterm birth. Among primiparae, women 40 years and older had a reduced risk of very preterm birth compared with women of 25-29 years (OR 0.74 [95% CI=0.66, 0.84]). Among multiparae, women 40 years and older had the same risk of very preterm birth compared with women of 25-29 years (OR 1.00 [95% CI=0.90, 1.12]). However, stratification by education revealed that the age gradient was limited to women with >12 years education among primiparae. The effect of maternal age on very preterm birth of twins differs according to parity. To some extent, that effect is further modified by education. Therefore, future analyses of maternal age and twin birth outcomes should account for measures of obstetric history and other factors, which may influence these results.     

Dietary intake of soy protein and tofu in association with breast cancer risk based on a case-control study

Soy food and its constituents may protect against breast cancer, but the association between soy intake and decreased breast cancer risk is inconsistent. We evaluated the relationship between breast cancer risk and the dietary intake of soy protein as measured by total soy food and tofu intake. Histologically confirmed cases (n = 362) were matched to controls by age (within 2 yr) and menopausal status. High soy protein intake was associated with reduced breast cancer risk in analyses adjusted for potential confounders including dietary factors among premenopausal women (odds ratio [OR] = 0.39 in the highest quintile, 95% confidence interval [CI] = 0.22-0.93, P for trend = 0.03) and postmenopausal women (OR = 0.22, 95% CI = 0.06-0.88, P for trend = 0.16). We also found an inverse association between total tofu intake and breast cancer risk among premenopausal women (for total tofu intake, OR = 0.23 in the highest quintile, 95% CI = 0.11-0.48, P for trend < 0.01; for at least 1 serving of tofu as the main ingredient per day, OR = 0.26, 95% CI = 0.13-0.55, P for trend < 0.01). We concluded that increased regular soy food intake at a level equivalent to traditional Korean consumption levels may be associated with a reduced risk of breast cancer, and this effect is more pronounced in premenopausal women.     

Low-to-moderate alcohol consumption and breast cancer risk by age 50 years among women in Germany

Studies of the association between alcohol drinking and breast cancer show a tendency towards an increase in risk for high consumption levels but yield less consistent results for low-to-moderate levels, particularly among premenopausal women. In a population-based case-control study in Germany, the authors determined the effect of alcohol consumption at low-to-moderate levels on breast cancer risk among women up to age 50 years. The study included 706 case women whose breast cancer had been newly diagnosed in 1992-1995 and 1,381 residence- and age-matched controls. In multivariate conditional logistic regression analysis, the adjusted odds ratios for breast cancer were 0.71 (95% confidence interval (CI): 0.54, 0.91) for average ethanol intake of 1-5 g/day, 0.67 (95% CI: 0.50, 0.91) for intake of 6-11 g/day, 0.73 (95% CI: 0.51, 1.05) for 12-18 g/day, 1.10 (95% CI: 0.73, 1.65) for 19-30 g/day, and 1.94 (95% CI: 1.18, 3.20) for > or = 31 g/day. The association with high daily ethanol intake of > or = 19 g was modified by educational level, such that odds ratios were 3.7, 1.6, and 0.7 for women with low, moderate, and high levels of education, respectively. These data suggest that low-level consumption of alcohol does not increase breast cancer risk in premenopausal women.     

Breast cancer, lactation history, and serum organochlorines

The authors analyzed the relation between lactation history, organochlorine serum levels-in particular, 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE)-and the risk of breast cancer within a subsampe from a larger breast cancer case-control study conducted among women living in Mexico City, Mexico, between 1990 and 1995. From the original study, they selected a random sample of 260 subjects (1:1 case/control ratio). Analysis was restricted to 120 cases and 126 controls who had given birth to at least one child and had complete information on all key variables. Serum DDE levels were higher among cases (mean = 3.84 microg/g lipids, standard deviation = 5.98) than among controls (mean = 2.51 microg/g lipids, standard deviation = 1.97). After adjustment for age, age at menarche, duration of lactation, Quetelet index, and serum DDT levels, serum DDE levels were positively related to the risk of breast cancer (adjusted odds ratio (OR)Q1-Q2 = 1.24, 95% confidence interval (CI): 0.50, 3.06; ORQ1-Q3 = 2.31, 95% CI: 0.92, 5.86; ORQ1-Q4 = 3.81, 95% CI: 1.14, 12.80; test of trend, p = 0.02). The increased risk associated with higher serum DDE levels was more apparent among postmenopausal women (ORQ1-Q4 = 5.26, 95% CI: 0.80, 34.30; test of trend p = 0.03). A longer period of lactation was associated with a slightly decreased risk of breast cancer independently of serum DDE levels (OR = 0.91, 95% CI: 0.85, 0.99 change in risk per 10 months of lactation). Serum DDT level was not related to the risk of breast cancer. The data suggest that high levels of exposure to DDE may increase women's risk of breast cancer, particularly among postmenopausal women.     

Effects of birth order and maternal age on breast cancer risk: modification by whether women had been breast-fed

BACKGROUND: Early life risk factors for breast cancer have been investigated in relation to hormonal, nutritional, infectious, and genetic hypotheses. Recent studies have also considered potential health effects associated with exposure to environmental contaminants in breastmilk. METHODS: We analyzed data from a population-based case-control study of women living in Wisconsin. Cases (n = 2016) had an incident diagnosis of invasive breast cancer in 2002-2006 reported to the statewide tumor registry. Controls (n = 1960) of similar ages were randomly selected from driver's license lists. Risk-factor information was collected during structured telephone interviews. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated from multivariable logistic regression. RESULTS: In multivariable models, maternal age and birth order were not associated with breast cancer risk in the full study population. The odds ratio for breast cancer risk associated with having been breast-fed in infancy was 0.83 (95% CI = 0.72-0.96). In analyses restricted to breast-fed women, maternal age associations with breast cancer were null (P = 0.2). Increasing maternal age was negatively associated with breast cancer risk among women who were not breast-fed; the odds ratio for breast cancer associated with each 5-year increase in maternal age was 0.90 (0.82-1.00). Higher birth order was inversely associated with breast cancer risk among breast-fed women (for women with 3 or more older siblings compared with first-born women, OR = 0.58 [CI = 0.39-0.86]) but not among nonbreast-fed women (1.13 [0.81-1.57]). CONCLUSION: These findings suggest that early life risk factor associations for breast cancer may differ according to breast-feeding status in infancy.