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PubMed1979

Labor supply behavior of prospective and new mothers.

Utilizing unique data generated from the National Longitudinal Surveys of Young Women, this paper examines the labor force participation of young mothers in the months immediately preceding and following the birth of the first child. Labor supply behavior at this point in the life cycle is described in greater detail than has hitherto been available. In addition, we analyze the independent effect of several factors of interest on the probability that a young woman will be in the labor force during various intervals surrounding the first birth.

Adolescent↗
PubMed1993

[Primiparae--the role of age on the duration and disorders in the progression of labor].

The authors have made a study of age influence on the delivery duration and the breaches of delivery progress by women giving birth for the first time. In 6 groups 742 first birth giving women are investigated. The authors have found out a correlation between the age growth, particularly after 25 years, and the total delivery duration increase. Using the Friedman's partogram, the delivery activity have been analyzed. Significance of delivery progress breaches are found out mostly during the active phase-protracted active phase and secondary protracted active phase. There wasn't found out correlations between the age and growth and the latent phase protraction, and the arrest disorders.

Adolescent↗
PubMed1996

[Analysis of population attributable risk of breast cancer in urban and mining districts inhabitants].

In order to study the risk factors associated with female breast cancer, two 1:2 matched case-control studies were conducted from 1986 to 1993 in five cities in Hubei province and from 1991 to 1994 in Pingdingshan coal mining districts in Henan province. The results of multivariate conditional logistic regression analysis showed that history of breast diseases, number of births, age of first birth were major risk factors for breast cancer in urban inhabitants. Their adjusted attributable risks (PARs) were 0.3917, 0.3564, 0.1414 respectively. The combined population attributable risks (PAR) for the three factors was 0.7419. History of breast disease, number of births, menstrual disorder, family history of breast cancer were major risk factors in the Mining districts. Their PARs were 0.1487, 0.4781, 0.1282, 0.0791 respectively. PAR for four factors was 0.6952.

Breast Neoplasms↗
PubMed1976

Labor force participation and family formation: a study of working mothers.

Drawing upon a sample of 638 mothers aged 18 to 40, with at least some marital work experience, significant associations were found between the extent, kind, and timing of employment and a series of family formation variables. Generally lower fertility, longer first birth intervals, and earlier use of birth control were associated with the longest work durations, the highest status jobs, and work before the birth of the first child. The data failed, however, to differentiate desired family size.

Adolescent↗
PubMedDate not supplied

A case-control study of breast cancer in Tianjin, China.

In a population-based case-control study of breast cancer in Tianjin, China, involving 300 cases and 300 population controls interviewed during 1985-1986, a number of strong risk factors were identified. Although average age at menarche was late by Western standards in this developing country (14.4 years), it was clearly related to risk. Women with their first menstrual period at age 12 years or earlier had 80% greater risk than women who started at age 17 years or later. Age at first full-term pregnancy was also strongly related to risk, with women whose first birth after age 30 years having 3.2 times the risk of women whose first birth was under age 20 years. Other established breast cancer risk factors in Western populations (family history of breast cancer, a history of benign breast disease, and use of oral contraceptives late in reproductive life) were also risk factors in this population. Parity and duration of lactation were both strongly protective against breast cancer development in univariate analyses. These two variables were highly correlated with each other and with age at first full-term pregnancy. Although the effects of each variable dissipated somewhat in multivariate analysis, our data strongly suggest that both parity and lactation independently contribute to breast cancer risk.

Adult↗
PubMedDate not supplied

The pattern of reproductive life in a Berber population of Morocco.

Reproductive patterns were studied from data collected in 1,450 Berber households in the province of Marrakesh, Morocco in 1984. Women aged 45-49 years had a mean of 8.9 pregnancies to achieve 5.7 living children. Social influences on fertility rates show the importance of tradition, particularly through time-dependent variables such as age at marriage, waiting time to first birth, interbirth intervals, and duration of breastfeeding. Birth control does not appear to affect the tempo of fertility; rather, its main use is to bring the reproductive period to a close. The comparison of two subsamples of women separated by a 25-year interval indicates an actual acceleration of the tempo of fertility by the reduction of waiting time to first birth and of interbirth intervals. The supposed ongoing process of demographic transition is not clearly observed in this population.

Adolescent↗
PubMed1997

Risk of recurrence of birth defects in Washington State.

A population-based study was conducted using maternally-linked birth certificate records from Washington State for 1980-93 to evaluate the risk of birth defect occurrence among infants with previously affected siblings, relative to infants whose siblings did not have birth defects. The risks of recurrence of similar and dissimilar defects were estimated, and the effects of change in paternity and/or city of residence were evaluated as proxies of genetic and environmental effects. At the first birth on record, 3322 women were identified in the linked certificates as giving birth to a child with a birth defect; 6620 women whose first birth did not result in an infant with a defect were randomly selected for comparison. Women with a malformed infant had an increased risk of having a malformed infant at the subsequent birth (Relative Risk = 1.9, [95% Confidence Interval (CI) = 1.5-2.4]), which did not vary by intervening changes in partner or residence. The risk of recurrence of the same general type of defect [RR = 11.7, 95% CI = 9.7-19.50] was much greater than that of occurrence of a dissimilar defect [RR = 1.5, 95% CI = 1.1-1.9]. This was consistent for all defect categories, and did not vary markedly by changes in partner or residence.

Birth Order↗
PubMed2002

Birth weight as a predictor of breast cancer: a case-control study in Norway.

The hypothesis that birth weight is positively associated with adult risk of breast cancer implies that factors related to intrauterine growth may be important for the development of this malignancy. Using stored birth records from the two main hospitals in Trondheim and Bergen, Norway, we collected information on birth weight, birth length and placenta weight among 373 women who developed breast cancer. From the same archives, we selected as controls 1150 women of identical age as the cases without a history of breast cancer. Information on age at first birth and parity were collected from the Central Person Registry in Norway. Based on conditional logistic regression analysis, breast cancer risk was positively associated with birth weight and with birth length (P for trend=0.02). Birth weights in the highest quartile (3730 g or more) were associated with 40% higher risk (odds ratio, 1.4, 95% confidence interval, 1.1-1.9) of breast cancer compared to birth weights in the lowest quartile (less than 3090 g). For birth length, the odds ratio for women who were 51.5 cm or more (highest quartile) was 1.3 (95% confidence interval, 1.0-1.8) compared to being less than 50 cm (lowest quartile) at birth. Adjustment for age at first birth and parity did not change these estimates. Placenta weight was not associated with breast cancer risk. This study provides strong evidence that intrauterine factors may influence future risk of breast cancer. A common feature of such factors would be their ability to stimulate foetal growth and, simultaneously, to influence intrauterine development of the mammary gland.

Adult↗
PubMed1987

Reproductive history and breast cancer in a population of high fertility, Costa Rica, 1984-85.

The relationship between breast cancer and women's reproductive history in Costa Rica was analyzed using logistic regression methods on data from 171 breast cancer cases and 826 population-based controls aged 25-58 years. The risk of breast cancer in nulliparous women under age 45 was 3 times that for parous women in the same age group. Women over 44 years of age with a parity greater than 4 had a risk of breast cancer of 0.3 compared to women of the same age but with a parity of 1-4. Neither breast-feeding nor birth interval showed an overall association with breast cancer independent of parity. Women with early age at first birth had a lower relative risk of breast cancer than women aged 20-24 at first birth, but only in two subgroups--women aged 45 and over and women with parity 1-4. Women without a completed pregnancy in the last 20 years had an elevated relative risk. However, results are not conclusive because some information is probably distorted by recall errors. Declines in fertility rates in the 1960s and 1970s may result in an increase of 30% in breast cancer incidence in Costa Rica between 1980 and the year 2000, according to the relative risks found in this study. In contrast, the effect of childlessness will probably not produce significant changes in national breast cancer trends.

Adult↗
PubMed1975

A study of breast cancer in Irish women.

In a study of 100 women with breast cancer and 200 unaffected women the epidemiological characteristic of breast cancer most commonly described--namely, an excess of nonparous women among cases when compared with controls, was not observed. It is suggested that two factors, a dearth of first births born to mothers under 20 years of age and an unusually high proportion of first births when aged 30 years or more, are responsible for this finding. No association was found between breast cancer and socioeconomic status, marital status, age at marriage, age at first pregnancy, parity, or age at menarche. Significant associations with breast cancer included age at natural menopause, hysterectomy, and breast trauma. These findings are discussed.

Adult↗
PubMed2004

A comparison of reproductive risk factors for CIS lesions and invasive breast cancer.

A differential effect of reproductive factors on the incidence of carcinoma in situ of the breast (CIS) and invasive cancer may indicate that hormonal factors related to reproductive history not only influence the initial steps towards breast cancer but also preinvasive malignant lesions. A comparison of reproductive factors was performed using a population-based cohort of 1.5 million Danish women born between 1935 and 1978. Between 1983 and 1998, 15,590 cases of invasive breast cancer and 871 cases of CIS were identified using a database with extensive clinical information. Number of births and age at first birth were similarly associated with the risk of being diagnosed with ductal carcinoma in situ (DCIS) compared to invasive breast cancer [RR(DCIS)(per birth)/RR(invasive)(per birth) = 1.03(0.93-1.14), RR(DCIS)(per 5yr) /RR(invasive)(per 5yr) = 1.06(0.96-1.17)]. Also, the short-term risk the first 10 years after birth was similar for DCIS and invasive cancer [RR(DCIS) /RR(invasive) = 0.90 (0.74-1.09)]. Additional analyses were performed according to characteristics of the DCIS lesion (size, malignancy grade, noncomedo or comedo type). In conclusion, our observations do not support the theory that reproductive history is associated with progression from noninvasive to invasive breast cancer.

Adolescent↗
PubMedDate not supplied

Consanguinity, spousal age at marriage and fertility in seven Pakistani Punjab cities.

A retrospective study was conducted on spousal age at marriage, time to first birth and total pregnancies in the populations of seven cities in the Pakistani province of Punjab. Consanguineous marriages were strongly favoured with coefficients of inbreeding (F) for the present generation ranging from 0.0236 to 0.0286. Male and female ages at marriage were younger in consanguineous unions and spousal age differences smaller than in their non-consanguineous counterparts. Time elapsed from marriage to first birth tended to be longer in consanguineous unions but, in general, they had more pregnancies. As consanguinity has been shown to be associated with increased ante- and postnatal mortality in these communities, reproductive compensation provides a credible explanation for the apparent enhanced fertility with inbreeding. However, the data equally could be interpreted in terms of greater reproductive span and/or biosocial compatibility of the consanguineous unions.

Adult↗
PubMed2005

Reproductive and hormonal factors and risk of brain tumors in adult females.

Causes of brain tumors are largely unknown, and there is an urgent need to identify possible risk factors. Several observations point to a possible role of reproductive hormones, but few epidemiologic studies have examined whether reproductive factors, such as age at menarche and parity, are associated with brain tumor risk. We conducted a multi-center case-control study of newly diagnosed glioma (n = 212) and meningioma (n = 151) and frequency-matched controls (n = 436) in women from hospitals in Phoenix, Arizona; Boston, Massachusetts; and Pittsburgh, Pennsylvania between 1994 and 1998. Research nurses interviewed patients regarding potential risk factors for brain tumors, including reproductive factors and hormone use. Unconditional logistic regression analyses were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Risk of glioma increased with older age at menarche [OR = 1.90 (95% CI = 1.09-3.32) for age at menarche > or =14 vs. <12 years]. Early age at first birth was associated with reduced risk of glioma [OR = 0.43 (95% CI = 0.23-0.83) for a first birth before age 20 vs. nulliparity], but there was little effect of number of births. Exogenous hormone use was also associated with a lower risk of glioma, but risks did not vary systematically according to duration of use or age at first use. Possibly owing to low statistical power, there were few noteworthy associations between meningioma and reproductive factors, other than a nonsignificant (p = 0.09) trend of increasing risk with increasing age at menopause. The findings suggest that hormonal exposures early in life may be associated with risk of glioma, but the evidence is inconsistent and does not point clearly to a specific causal or protective hypothesis.

Adolescent↗
PubMed1987

A prospective study of reproductive factors and breast cancer. II. Age at first and last birth.

The relations between age at first and last full-term pregnancy and breast cancer risk were investigated after 20 years of follow-up of 63,090 Norwegian women, among whom 1,565 breast cancer cases occurred. An association seen in preliminary analyses between early age at first birth and low risk of breast cancer was removed after adjustment for parity and age at last birth. Age at last birth showed initially no association with breast cancer. After adjustment for parity, however, a significant positive association emerged. The authors' observations suggest that the relation between age when a pregnancy occurs and breast cancer risk may be more complex than previously believed. Despite the overall association between increasing parity and lower risk, the women with many late pregnancies and those with few, widely spaced pregnancies had higher risk than nulliparous women, indicating that both the age when pregnancy occurs and the length of intervals between successive births may modify the protective effect. The findings are consistent with a dual effect of a pregnancy, causing a transient increase followed by a subsequent strong and long-lasting decrease in risk of breast cancer.

Adult↗
PubMed1999

Contraceptive use dynamics of Asian women in Britain.

In-depth interviews were conducted with married Asian women from Indian, Pakistani and Bangladeshi backgrounds, to investigate patterns of contraceptive use and influences on contraceptive decision making. The results show two distinctively different contraceptive 'lifecycles'. Non-professional women typically have little knowledge about contraception until after their marriage or first birth. Their patterns of contraceptive behaviour show low levels of contraceptive use until after their first birth, when condom use is most prevalent. Non-professional women are influenced by their extended family, religion and cultural expectations on their fertility and family planning decisions. Professional women show an entirely different pattern of contraceptive behaviour. They are more likely to have knowledge about contraception before marriage, use some method of contraception throughout their childbearing years (typically the pill) and cite personal, practical or economic considerations in their fertility decisions rather than religious, cultural or extended family influences.

Adult↗
PubMed2005

Use of antibiotics and risk of breast cancer: a population-based case-control study.

We examined the use of antibiotics among 2728 women with a first diagnosis of breast cancer during 1994-2003, and 27 280 population controls in North Jutland County, Denmark, based on hospital discharge diagnoses, prescription use from 1989 to 2002, and population registry data. We found no increased relative risk of breast cancer associated with use compared with nonuse. The odds ratio for breast cancer associated with more than 10 prescriptions for antibiotics was 1.00 (95% CI 0.86 -1.15). Relative risks were similar for different classes of antibiotics. A subanalysis based on cases and controls younger than 70 years of age, with data on first birth and number of children, showed similar risk estimates even after adjustment for age at first birth and parity. In our study, use of antibiotics was not associated with an increased risk of breast cancer.

Aged↗
PubMedDate not supplied

[Relationship between reproductive patterns and infant mortality: alternative interpretations].

A secondary analysis of the data of the Mexican National Fertility and Health Survey of 1987 (ENFES for its spanish acronym) was undertaken in order to study the relationship between reproductive patterns and child mortality. A total of 13,216 births and 711 infant deaths occurred 1 to 15 years previous to the survey were studied. The main conclusions are: 1) it is the adverse social, economic and environmental conditions surrounding young mothers (15 to 19 years) which are responsible for the excess mortality found in their children; 2) children of older women (35 and more years) experience increased mortality only in the late fetal period, this suggesting that a biological mechanism is mainly at stake; 3) the relative risks of death of first births, as compared to subsequent ones are generally smaller than one, indicating that first births have a lower probability of dying. The relative risk of death of first born relative to subsequent births, on the other hand, decreases with increasing age at death, suggesting that biological factors such as low birthweight and intrapartum complications are possibly important as well; 4) relative risks of death for short-spaced as compared to well spaced births were found, in general, to decrease from the late fetal to the neonatal and to the postneonatal periods. This points to a biological pathway, possibly via maternal nutrition, for the effect of spacing on child mortality.

Adolescent↗
PubMed2006

Incidence of ovarian cancer of grand multiparous women--a population-based study in Finland.

OBJECTIVES: Parity is known to induce protective effects on ovarian cancer. This study aimed to evaluate how far upon births the protection reaches, the effect of age at first birth, the interval between births in the whole population and the length of time from the first to the last birth and from the last birth to cancer among postmenopausal women. METHOD: The population-based cohort consisted of 87,929 grand multiparous (GM) women, i.e. women with at least 5 deliveries. Standardised incidence ratios (SIRs) were calculated by dividing the number of observed cancer cases by the expected number based on the national incidence rates, both extracted from the population-based Finnish Cancer Registry. Conditional logistic regression for the case-control design nested in the GM cohort was used to estimate proportional hazards by different factors. RESULTS: The SIR for ovarian cancer among GM women was low (418 cases; SIR 0.64, 95% confidence interval 0.58-0.69). Further births over five did not give additional protection. The relative risk did not vary significantly by age at first birth or interval between the births in any histological subtype. CONCLUSION: The risk of ovarian cancer was low in all GM women no matter how many children and at which ages they had delivered or contracted cancer.

Adult↗