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PubMed2006

Longitudinal patterns of breastfeeding initiation.

Breastfeeding, in spite of proven benefits and energetic promotion, lags behind national goals, is less prevalent in disadvantaged populations, and declines across successive children in a family. Using longitudinally linked data from the New Jersey Electronic Birth Certificate (EBC) from 1996 to 2001, we found considerable fluidity in breastfeeding status at hospital discharge for births to the same mother. Among mothers who breastfed exclusively after the first birth, only 69% did so after the second (we refer to this as recurrence). Among mothers who exclusively formula fed after the first birth, 16% initiated exclusive breastfeeding after the second birth (referred to as recruitment). Combination feeding the first born, i.e., breastfeeding supplemented by formula, was followed by exclusive breastfeeding for 38% of second births. Rates of recurrence and recruitment differed in distinct ways by race/ethnicity and immigrant status. We conclude that breastfeeding initiation is not necessarily or exclusively a matter of fixed preferences, and that opportunities exist to expand breastfeeding to realize national goals by enhancing both recurrence and recruitment.

Adult↗
PubMed1996

Age at first full-term pregnancy, lactation and parity and risk of breast cancer: a case-control study in Spain.

A case-control study was carried out in Spain to assess associations between parity, lactation and age at first full-term pregnancy and breast cancer. From November 1989 to February 1992, 184 incident breast cancer histologically confirmed cases were interviewed and matched by age and residence to 184 hospitalized patients and 184 community controls selected by random digit dialing. Multiple logistic regression was used to assess the independent influence of each factor on the risk of breast cancer in relation to other factors included in the model. Age at first full-term pregnancy was associated with breast cancer risk with an estimated odds ratio of 3.5 (95% CI 1.41-9.83) for women with their first birth after 30 years in comparison with those whose first birth was before age 21. Breast cancer risk decreased with increasing number of full-term pregnancies, OR 0.3 (95% CI 0.16-0.78) for women who had had more than 3 full-term pregnancies in comparison with nulliparous women. Among parous women, the estimated OR for women with more than 3 children was 0.4 (95% CI 0.13-0.81) after allowance for age at first childbirth and lactation. The estimated OR was 2.6 (95% CI 1.4-4.7) for women with a positive history of breast cancer in first-degree relatives. Breast cancer was not associated with total duration of lactation. The study indicates that parity is an independent risk factor associated to breast cancer and that the women with a late age at first full-term pregnancy constitute a high-risk group.

Breast Neoplasms↗
PubMed2006

Association between infant birth weight and maternal cardiovascular risk factors in the health, aging, and body composition study.

PURPOSE: Mothers who deliver a low-birth-weight (LBW) infant may themselves be at excess risk for cardiovascular disease. We investigated whether older women who bore LBW infants had higher blood pressure, lipid, glucose, insulin, interleukin 6 (IL-6), and C-reactive protein concentrations, and pulse wave velocity compared to women with normal-weight births. METHODS: Participants were 446 women with a mean age of 80 years and 47% black. Women reported birth weight and complications for each pregnancy. Analysis was limited to first births not complicated by hypertension or preeclampsia. RESULTS: Women who had delivered a first-birth infant weighing less than 2500 g had a lower body mass index (BMI) compared with women with a normal-weight (>or=2500 g) infant (26.7 versus 28.4 kg/m2; p=0.02), but they had a larger abdominal circumference for BMI (97.9 versus 95.5 cm; p=0.05). They also were marginally more likely to be administered antihypertensive medication (p=0.06). After adjustment for BMI, race, and age, women with a history of a small infant had elevations in systolic blood pressure (p=0.05) and greater IL-6 levels (p=0.02) and were more insulin resistant (p=0.05) compared with women with a normal-weight infant. CONCLUSIONS: These findings suggest that a history of LBW delivery identifies women with elevated cardiovascular risk factors.

Black or African American↗
PubMed1990

Effects of maternal birth season on birth seasonality in the Canadian population during the seventeenth and eighteenth centuries.

Birth records of the French-Canadian population for the period 1621-1765 were analyzed retrospectively to examine the effect of maternal birth season on the seasonal distribution of births. Preliminary examination indicated that there was a bimodal pattern in birth seasonality: a major peak in early spring, a trough in early summer, a minor peak in autumn, and a trough around December. Because this seasonality was strongly biased at the level of the first birth by the month of marriage, which was concentrated in November, the seasonality of nonfirst births (n = 32,926) was examined in relation to the four seasons of maternal birth. Mothers born in May-July showed a flatter monthly distribution of nonfirst births at a maternal age of 28 years or more. Analysis of marriage-first birth intervals indicated that mothers who married in August-October showed a lower percentage of immediate conception (intervals of 8-10 months), whereas those mothers born in May-July had a higher percentage of immediate conception. This difference in birth seasonality shown by mothers born in May-July is similar to results from early twentieth-century Japan. Some seasonal infertility factors could have affected the embryos at the earliest stage of pregnancy, modifying a part of the seasonal variation in birth rate.

Birth Intervals↗
PubMed2006

First-time births among women 30 years and older in the United States: patterns and risk of adverse outcomes.

OBJECTIVE: To update the trends in initiation of childbirth by age of the mother, describing the characteristics of women having their first child at age 30 or above, and to determine the risk for adverse pregnancy outcomes for this group of women. STUDY DESIGN: This was a cross-sectional study using National Center for Health Statistics linked live birth and infant death cohort files from 1995 to 2000, and Natality file from 1980 to 2002. Analysis was limited to index pregnancies only. Logistic regression analysis was used to determine the risk of poor outcomes. RESULTS: There is a decreasing trend of first-time births to women 20-29 years old, while births to women 30 and older are showing a continued rise. As compared to 20-29-year-olds, women who start childbearing at age 30 or older are at increased risk of maternal complications in general. However, 30-34-year-olds have a reduced risk for pregnancy-induced hypertension and pre-existing hypertension. Infants born to women aged 30 and above are at increased risk for prematurity and low birth weight in addition to fetal and infant mortality. CONCLUSION: Because of the increasing trend of women starting childbearing in their 30s and the increased risk for poor outcomes in older women, health providers need to pay extra attention to this group of women as they plan and deliver services for them.

Adult↗
PubMed1993

Extra-marital births occurring in cohabiting unions.

"Accompanying the rapid rise of unmarried cohabitation and the decline in nuptiality, Britain experienced a sharp increase in the number and proportion of births outside wedlock....84% of this recent increase corresponds to jointly registered births which can therefore be assumed to occur to informal couples. This chapter explores this new fertility trend using General Household Survey data for 1989, focusing on first births to single never-married cohabitants. The informality of cohabitation as a living arrangement and shortfalls in the data...are discussed....The chapter then attempts to provide some insights into the circumstances of the first birth, the timing of birth and marriage and the relative levels of fertility in the different unions."

Birth Order↗
PubMed1990

Age at first and second births and breast cancer risk in biparous women.

The role of age at first and at second birth on subsequent breast cancer risk was analyzed using pooled data from 2 hospital-based case-control studies conducted in Italy, for a total of 1,200 biparous cases and 987 controls. Compared with women who gave birth for the first time below age 20, the relative risks were above unity for those with later first birth, even after allowance for age at second birth, although the trend was inconsistent across subsequent strata. A similar direct trend in risk was observed in relation to age at second birth: compared with less than 25 years and after allowance for age at first birth, the point estimates were 1.2, 1.4 and 1.4 for 25-29, 30-34 and greater than or equal to 35 (p for linear trend = 0.04). The results for age at first and at second birth were similar in the 2 studies pooled in this analysis. A significant interaction with age was observed in relation to age at first and at second birth. In younger women (below age 50) a strong and direct association with age at first birth was found, while no apparent protection was conveyed by earlier second birth. Among older women (aged 50 or over), there was no apparent relationship with age at first birth after allowance for age at second, but the role of age at second birth was independent and statistically significant. Thus, our study confirms an independent and significant role of age at second birth in biparous women, after allowance for age at first birth, and indicates that, after reciprocal allowance, the role of first and second birth was not apparently different. The relative risks for both variables were quantitatively moderate, and may be influenced by age or other temporal variables.

Adult↗
PubMed1985

Occurrence of breast cancer in relation to diet and reproductive history: a case-control study in Fukuoka, Japan.

An epidemiologic study on breast cancer in relation to diet and reproductive history was conducted with 3 populations at different levels of risk for the disease: Japanese in Fukuoka, Japan (low risk), Japanese in Hawaii (intermediate risk), and Caucasians in Hawaii (high risk). This report describes the Fukuoka portion of the study. We interviewed 212 patients with histologically confirmed breast cancer and an equal number each of hospital and neighborhood controls to determine risk factors for the disease. The results indicated that "overnutrition" (a high-fat and high-animal protein diet) was not statistically associated with the disease. As noted in previous studies, age at the first birth was positively related to the disease; those women who gave birth to their first child when they were 35 or more years of age showed a relative risk of 5.0 compared with those giving birth at less than 20 years of age. A past history of both natural abortion and of benign breast disease were significantly associated with the disease. On the whole, the results obtained from this Fukuoka portion of study were in good agreement with those from the Hawaii study during which Japanese and Caucasians in Hawaii were investigated.

Adolescent↗
PubMed1989

Classification of small-for-gestational age births: weight-by-gestation standards of second birth conditional on the size of the first.

Percentiles of weight-by-gestational age were constructed for first and second births, based on linked sibship-data from the Medical Birth Registry of Norway. Standards were made for weight-by-gestational age of second births conditional on whether the first birth was small-for-gestational age (SGA) or large-for-gestational age (LGA). These standards were compared with the conventional, cross-sectional standard of all second births. The relevance of the conditional standards was assessed on the basis of perinatal mortality, using logistic regression analyses. When applying cross-sectional standards of second births, more than 30% of the births following a SGA first birth were classified as SGA, compared with only 1.7% following an LGA first births. The overall risk for a perinatal loss in second births following a SGA first birth was twice that among second births following a LGA first birth. When second births were themselves categorised as SGA or non-SGA using the cross-sectional standards, the mortality among the SGA second births was such that the risk was 4 to 5 times higher following LGA first births compared with SGA first births. When conditional standards were applied to define SGA among second births, the risk relation between the subgroups (defined by classification of first birth) corresponded to the observed overall risk pattern. An unconditional SGA classification conceals important differences between clinically distinct subgroups.

Birth Weight↗
PubMed1996

Anthropometric and reproductive factors and the risk of pancreatic cancer: a case-control study in Shanghai, China.

To examine the possible role of body size and reproductive factors in pancreatic cancer, data were analyzed from a population-based case-control study conducted in Shanghai, China. Cases (n = 451) were permanent residents of Shanghai, 30-74 years of age, newly diagnosed with pancreatic cancer between October 1, 1990, and June 30, 1993. Deceased cases (19%) were excluded from the study. Controls (n = 1,552) were randomly selected from permanent Shanghai residents and frequency-matched to cases by gender and age. Information on body size and reproductive and other possible risk factors was collected through personal interviews. After adjustment for age, income, smoking and other confounders, a positive dose-response relation between body mass index and risk of pancreatic cancer was observed in both sexes. Among women, the risk of pancreatic cancer was significantly associated with number of pregnancies and live births. Compared with 0-2 pregnancies or live births, the odds ratio (OR) for 8 or more pregnancies was 1.90, while that for 5 or more births was 1.88. A modest elevation in risk, independent of parity, was associated with early age at first birth. Risk increased over 40% among women with a first birth at or before age 19 years relative to those at age 26 years or older. Ever use of oral contraceptives was associated with excess risk, though based on small numbers of users. Our findings suggest that, in Shanghai, obesity, gravidity, parity and perhaps use of oral contraceptives are associated with moderate increases in risk of pancreatic cancer, indicating that hormonal determinants deserve further investigation.

Aged↗
PubMed1988

Short term increase in risk of breast cancer after full term pregnancy.

To determine whether there is a short term increase in the risk of breast cancer after a full term birth data from two hospital based, case-control studies in Italy were pooled. Analysis was restricted to women aged under 50 with two or more children (573 women with cancer and 570 controls). A relative risk for breast cancer of 2.66 was seen in women who had given birth during the three years preceding the interview compared with women whose last birth had occurred 10 or more years before, after adjustment for age, age at first birth, and parity. The relative risk slowly decreased for women who had last given birth three to 10 years before. Multivariate analyses confirmed the protective effect of an early age at first birth and the age dependent effect of parity on the risk of breast cancer--that is, a direct relation below age 40 and an inverse one in older women. These data provide epidemiological evidence that a full term birth is followed by a transient increase in the risk of breast cancer, which for some time contrasts with and overcomes the long term protection of pregnancy at an early age. They therefore confirm predictions from animal studies and theoretical models that pregnancy prevents the early stages of breast carcinogenesis but promotes the late stages of the process.

Adult↗
PubMed1998

Marriage season, promptness of successful pregnancy and first-born sex ratio in a historical natural fertility population--evidence for sex-dependent early pregnancy loss?

We investigated population-based vital records of the seventeenth and eighteenth century French Canadian population to assess the effects of marriage season on the outcome of the first births under natural fertility conditions (n = 21,698 marriages). Promptness of the first successful conception after marriage differed according to marriage season; the proportion of marriages with a marriage-first birth interval of 8.0-10.0 months was lowest (34%) for marriages in August-October (P = 0.001). Although the male/female sex ratio of the babies born with an interval of 8.0-10.0 months was generally higher (1.10) than those with an interval of 10.0-24.0 months (1.05), the marriages in August-October resulted in a significantly reduced sex ratio (0.96) among only the prompt conceptions (P = 0.026). We discuss whether this seasonal reduction of the sex ratio could be partly explained by a clustered pregnancy loss of male zygotes in early pregnancy.

Adult↗
PubMed2000

Risk factors among young women with endometrial cancer: a Danish case-control study.

OBJECTIVE: This study was undertaken to identify and quantify risk factors for endometrial cancer among young women. STUDY DESIGN: This case-control study included all Danish women <50 years old who had endometrial cancer diagnosed during the period 1987 to 1994. A total of 237 case patients and 538 population control subjects matched with the case patients for age and residence were included in the analysis. RESULTS: Women with a family history of endometrial cancer had an odds ratio for endometrial cancer of 2.1 (95% confidence interval, 1.1-3.8)). Completion of 1 term pregnancy implied an odds ratio of 0.6 (95% confidence interval, 0.3-1.1). The risk of endometrial cancer decreased significantly with increasing age at first birth and with the number of induced abortions. Use of oral contraceptives for 1 to 5 years decreased the risk of endometrial cancer (odds ratio, 0.2; 95% confidence interval, 0.1-0.3). The odds ratio for endometrial cancer among women who received hormone replacement therapy for 1 to 5 years was 3.1 (95% confidence interval, 1.4-7.0). Body mass index was not demonstrated to be an independent risk factor in this study. The protective impacts of the different exposures (risk factors) can be expressed as etiologic fractions, which indicate how much each exposure reduces the occurrence of endometrial cancer compared with a situation without the existence of that particular exposure. These fractions were as follows: oral contraceptive use for > or =1 year, -45%; 2 term pregnancies, -88%; age > or =30 y when giving birth for the first time, -38%; and a history of incomplete pregnancy, -16%. CONCLUSION: A number of risk factors for endometrial cancer are common to premenopausal and postmenopausal women: family history, reproductive history, hormone replacement therapy, and the use of oral contraceptives. Among young women reproductive variables imply the greatest prophylactic potential.

Abortion, Induced↗
PubMed2002

Pregnancy related protection against breast cancer depends on length of gestation.

In a prospective study of 694 657 parous women in Norway, 5474 developed breast cancer after their first birth. If the first pregnancy lasted less than 32 weeks, the risk was 22% (95% confidence interval, -3% to 53%) less than after a pregnancy of 40 weeks or more, with a significant declining trend in risk (P for trend=0.02).

Adult↗
PubMed1986

Relationship between risk factors for breast cancer and hormonal status.

A total of 512 breast cancer patients and 540 controls were compared to examine the risk factors for different categories of breast cancer as defined by age, menopausal status and estrogen receptor (ER) tumor status. Significant differences were found by menopausal status, for age at first birth and age at menarche for all women, and for age at first birth and family history for women between 45 and 54 years old. No significant differences were found with ER status alone; however there was a significant difference between ER status and body weight in premenopausal women; the above significant differences with menopausal status were not found when stratified by ER tumour status. These findings support the hypothesis for aetiological differences for pre- and postmenopausal breast cancer and suggest that ER tumour status may influence the risk associated with body weight.

Adult↗
PubMed2000

Characteristics of respondents and non-respondents from a case-control study of breast cancer in younger women.

BACKGROUND: This study assessed the nature of potential biases by comparing respondents with non-respondents from a case-control study of breast cancer in younger women. METHODS: The case-control study was conducted in three regions in the US: Atlanta GA, Seattle/Puget Sound WA, and central New Jersey. An abbreviated interview or mailed questionnaire was completed by willing non-respondents, most of whom had refused participation in the main study. RESULTS: Respondents and non-respondents appeared similar with respect to age, race, relative weight, smoking, family history of breast cancer, number of births, age at first birth, and several dietary items. Compared to non-respondents, case and control respondents were of shorter stature, and reported less frequent consumption of doughnuts/pastries. Respondent cases, compared with non-respondent cases, were more highly educated and more likely to have consumed alcohol regularly; similar but not statistically significant tendencies were observed for controls. Respondent cases experienced menarche earlier than non-respondents. Respondent controls were more likely to have used oral contraceptives than non-respondents; a similar but not statistically significant tendency was observed in cases. Comparisons of crude and simulated relative risks using available non-respondents' data generally showed a low impact of non-response on relative risks in this study. CONCLUSIONS: Our results suggest that non-response would not greatly affect relative risk estimates in this study, except possibly regarding height. However, we were limited by the numbers of informative non-respondents and the amount of data collected. Collecting similar information in future studies would be useful, especially since varying methods used to encourage participation may lead to differences in respondents' characteristics.

Adult↗
PubMed2002

Adverse reproduction outcomes among employees working in biomedical research laboratories.

OBJECTIVES: The aim of the study was to investigate reproductive outcomes such as birthweight, preterm births, and postterrm births among women working in research laboratories while pregnant. METHODS: Female university personnel were identified from a source cohort of Swedish laboratory employees, and the database was linked to the medical birth register. The first births of the women were included in the analysis, 249 pregnancies among the women with laboratory work and 613 pregnancies among the women without laboratory tasks. Information about exposure to various laboratory agents was obtained from a previous questionnaire investigation at the research group level according to a specific definition. The ponderal index and ratio between observed and expected birthweights were calculated. Logistic regression models were used for analyses of dichotomous outcomes (preterm, postterrm and birthweight). RESULTS: Exposure to laboratory work with solvents was associated with an increased risk of preterm births, the estimated odds ratio (OR) being 3.4 (1.0 < 95% confidence interval < 11.9). An association with work with bacteria was also observed for postterm births (OR 2.7, 1.0 < or = 95% confidence interval < 7.4). CONCLUSIONS: There was a slightly elevated risk for some reproductive outcomes among the women working with certain laboratory tasks, specifically for preterm and postterm births in relation to work with solvents and bacteria.

Birth Weight↗
PubMed1999

Human sex ratio at birth and mother's birth season: multivariate analysis.

We used a population-based historical French Canadian database to examine the effects of mother's birth season on sex ratio at birth. Non-first births in the database (n = 127,658) were analyzed for their sex, parish size (2 large parishes of Montreal and Quebec or the other smaller parishes), time period (births up to 1719 or those from 1720), maternal age (< or = 24, 25-29, 30-34, 35+ years), sex of the preceding sibling (male or female), and birth seasons of the child and his or her parents (February-April, May-July, August-October, November-January). Season of child's birth significantly affected the sex ratio (chi 2 = 11.507, d.f. = 3, p = 0.009), with the births in February-April or May-July showing a lower sex ratio. Season of mother's birth also contributed highly significantly to the variation of sex ratio (chi 2 = 15.196, d.f. = 3, p = 0.002); mothers born in February-April had a low sex ratio among their children (sex ratio = 1.013). In contrast, season of father's birth did not affect the sex ratio (chi 2 = 0.618, d.f. = 3, p = 0.892). When a multiple logistic model was applied to the data, mother's birth season was the single most significant factor. The lower sex ratio from mothers born in February-April was observed consistently for every maternal age and delivery season. Seasonal influences on female fetuses seem to have changed their future reproductive characteristics.

Canada↗