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Infant health consequences of childbearing by teenagers and older mothers.

The association of childbearing at early and late ages with various adverse outcomes of pregnancy was explored in data collected in the 1980 National Natality and Fetal Mortality Surveys. The characteristics of interest for teenage mothers were marital status at conception and the trimester of pregnancy in which prenatal care was begun. For married mothers aged 30 years and older, the variables considered were employment status and occupation during the year preceding childbirth and smoking status before and during pregnancy. The pregnancy outcome variables analyzed were the same for both groups of mothers: fetal loss, low birth weight, and low 1-minute Apgar scores. Although more than half of all births to teenage mothers were to unmarried women, an additional one-quarter of these births were to women who married between the time of conception and the birth of the child. Generally there was little difference in outcomes for teenage mothers who were married at the time of delivery, regardless of their marital status at the time of conception. Pregnancy outcomes for teenagers who did not marry prior to delivery were considerably less favorable. Nearly 90 percent of women aged 30-34 years who had a first birth in 1980 were employed during the year before delivery, an extraordinarily high labor force participation rate. More than half of these employed mothers were in professional occupations, consistent with their very high levels of educational attainment. Although the analysis is limited by the small numbers of births involved, it appears that professionally employed women generally have the best pregnancy outcomes. When mother's smoking status is taken into account,nonsmokers had more favorable outcomes, with births to professionally employed mothers generally most favored.

Adolescent↗

Maternal employment in Scandinavia: a comparison of the after-birth employment activity of Norwegian and Swedish women.

"A striking characteristic of recent Western labour market trends is the rise in employment among mothers of very young children. So far, few studies have analysed the impact of public policies on employment rates of young mothers. In this study we address this issue by comparing two similar countries, Norway and Sweden, which have the same set of policies with slight variations, using data sets with similar designs. We analyse rates of re-entry into paid work after first birth for mothers in 1968-88 by means of hazard regression. One important finding is that the right to paid maternity leave with job security greatly speeds up the return to work."

Developed Countries↗

Breast cancer mortality rates are levelling off or beginning to decline in many western countries: analysis of time trends, age-cohort and age-period models of breast cancer mortality in 20 countries.

Age-standardised mortality rates for breast cancer were examined for 20 countries in Europe, North America, Australia and New Zealand from 1950 to 1992 and age-birth cohort and age-period of death models were fitted to the data. Breast cancer mortality rates generally increased in the earlier decades, but more recently rates have levelled off or begun to decline in most countries. Only in 4 of the 20 countries studied, Belgium, Hungary, Poland and Spain, was there no evidence of a decline or leveling off or mortality in recent birth cohorts or in recent years. In the other countries the decline in mortality appeared to be in part due to birth cohort effects and in part due to period effects. The birth cohort effects were suggestive of a decline in breast cancer rates among women born after about 1920 and were evident in many countries especially Canada, The Netherlands, The United Kingdom and the United States. The decline in mortality in women born after 1920 appeared to be in part related to a reduction in childlessness and a reduction in age at first birth in those generations. As well as the birth cohort effects, there was some evidence of a recent overall decline in mortality rates in several countries, e.g. Austria, FRG, Greece and the UK, and this may be due to an increase in survival resulting from improved management and treatment of women with breast cancer.

Adult↗

The effects of maternal smoking on fetal and infant mortality.

Although maternal cigarette smoking has been shown to reduce the birth weight of an infant, previous findings on the relation between smoking and fetal and infant mortality have been inconsistent. This study used the largest data base ever available (360,000 birth, 2,500 fetal death, and 3,800 infant death certificates for Missouri residents during 1979-1983) to assess the impact of smoking on fetal and infant mortality. Multiple logistic regression was used to estimate the joint effects of maternal smoking, age, parity, education, marital status, and race on total mortality (infant plus fetal deaths). Compared with nonsmoking women having their first birth, women who smoked less than one pack of cigarettes per day had a 25% greater risk of mortality, and those who smoked one or more packs per day had a 56% greater risk. Among women having their second or higher birth, smokers experienced 30% greater mortality than nonsmokers, but there was no difference by amount smoked. The prevalence of smoking in this population was 30%. It was estimated that if all pregnant women stopped smoking, the number of fetal and infant deaths would be reduced by approximately 10%. The higher rate of mortality among blacks compared with whites could not be attributed to differences in smoking or the other four maternal characteristics studied. In fact, the black-white difference was greater among low-risk women (e.g., married multiparas aged 20 and over with high education) than among high-risk women (e.g., unmarried teenagers with low education).

Adolescent↗

Parity and incidence of non-insulin-dependent diabetes mellitus.

PURPOSE: To examine prospectively the association between parity and subsequent incidence of non-insulin-dependent diabetes mellitus (NIDDM). Most previous studies have not controlled for potential confounding by age and obesity. PATIENTS AND METHODS: In a prospective cohort study, 113,606 United States registered nurses aged 30 to 55 years and free of diagnosed diabetes, coronary heart disease, stroke, and cancer at baseline were followed for 12 years. Endpoint was incidence of confirmed NIDDM. RESULTS: During 1,278,188 person-years of follow-up, we confirmed 2,310 incident cases of NIDDM. An apparent association between parity and diabetes was observed in unadjusted analyses (relative risk = 1.56 [95% confidence interval (CI), 1.27 to 1.91] among women with six or more births compared with that in nulliparous women) (p, trend less than 0.00001). This association was attenuated after adjustment for age (relative risk = 1.19 [CI 0.97 to 1.48], p, trend = 0.06) and was completely abolished after adjustment for both age and body mass index (relative risk = 0.95 [CI 0.75 to 1.19], p, trend = 0.19). Multivariate adjustment for family history of diabetes, age at first birth, hormone use, and other variables did not materially alter these findings. There was no important modifying effect of family history of diabetes on these associations. CONCLUSIONS: Despite a temporary diabetogenic effect of pregnancy, parity is not associated with an increased risk of subsequent clinical NIDDM. These data underscore the importance of control for confounding by age and obesity in evaluating these associations.

Adult↗

Hormonal factors and pancreatic cancer in women.

PURPOSE: The aim of the study was to evaluate hormonal risk factors for carcinoma of the exocrine pancreas among postmenopausal women. METHODS: Mailed questionnaire data from 52 cases and 233 population-based controls in Ontario were used to assess parity, age at first birth, and other hormonal factors on pancreatic cancer risk. RESULTS: Reduced risk was seen with three or more pregnancies [adjusted odds ratio (OR) = 0.22, 95% confidence interval (CI) = 0.07-0.65] and use of oral contraceptives (adjusted OR = 0.36, 95% CI = 0.13-0.96), whereas no significant associations were found for age at menarche or menopause, or estrogen replacement therapy. Among parous women, later age at first full-term pregnancy significantly increased the risk of this cancer (adjusted OR = 4.05, 95% CI = 1.50-10.92 for ages 25-29 years, adjusted OR = 3.78, 95% CI = 1.02-14.06 for ages 30+ years). CONCLUSIONS: Our data support the hypothesis that pancreatic cancer is, at least in part, an estrogen-dependent disease; there is growing epidemiological evidence that aspects of reproductive history and hormonal exposure are associated with risk of this disease.

Adolescent↗

Waiting for Trivers and Willard: do the rich really favor sons?

Parental investment theory has been put forward as a major evolutionary argument explaining male or female biased birth sex ratio, the Trivers-Willard (T-W) hypothesis, predicting that parents living in good circumstances will bias their investment to sons, whereas parents in poor circumstances will bias their investment toward daughters. Tests of the T-W hypothesis on human beings have shown limited evidence for parents appearing to differentiate their investment to sons or daughters according to the reproductive potential of each sex. The present study tests the T-W hypothesis among a large contemporary Polish sample using first birth interval and extent of breastfeeding as measures of parental investment, and economic status and level of parental education as measures of parental condition. The extents to which parental investment and markers of parental condition vary by sex of the child were examined using log-linear analysis. Weak support for the T-W effect is found among families where fathers were best educated, where a greater proportion of first-born boys are breastfed longer than girls, while the opposite trend is observed among families with fathers with lowest levels of education. Although the present study does not fully support the T-W hypothesis, it gives evidence of greater investment in female offspring at the lower extremes of income, and greater investment in males at higher levels of income.

Adult↗

The effect of female age on the likelihood of a live birth from one in-vitro fertilisation treatment.

OBJECTIVE: To determine the chance of at least one live birth from one round of in-vitro fertilisation (IVF) treatment and the effect of the woman's age on that likelihood. DESIGN: Retrospective analysis of outcomes from IVF treatment that did not involve donated gametes, but which included embryos cryopreserved in the retrieval cycle. SETTING AND PATIENTS: All IVF patients (median age, 36 years; range, 22-48 years) who attended a private IVF clinic in Sydney for an egg retrieval between 1 January 1998 and 31 December 1998, and had embryo placements (fresh and cryostored) performed up to 30 June 2001. MAIN OUTCOME MEASURE: Independently audited live births surviving the neonatal period. RESULTS: 565 women had 648 egg retrievals during the period. The age of peak utilisation of IVF was 39 years. For women aged 34 years or less, the chance of a live birth from one round of egg retrieval and IVF treatment was 52.4% (95% CI, 47%-59%). For women aged 35-44 years, there was a linear decline in the live birth rate, and no babies were born from retrievals at age 45 years and over. There was an age-dependent rise in the frequency of miscarriages, from 10.5% (95% CI, 5%-18%) for women under 35 years, to 16.1% (95% CI, 9%-25%) for those 35-39 years, and 42.9% [95% CI, 24%-63%] for those over 40 years (P < 0.001). A third of the first births resulted from embryo transfers performed after a period of cryostorage. CONCLUSION: As fertility with IVF falls from the age of 34 years, and the age of peak IVF utilisation is 39 years, many Australian women are seeking IVF at an age when the likelihood of a live birth is reduced.

Abortion, Spontaneous↗

Breast cancer risk in women who have had children with different partners.

The fetal antigen hypothesis suggests that the lowered risk of breast cancer in parous women may be afforded by the development of antibodies to fetal antigens that are structurally similar to mammary cancer antigens. It has previously been hypothesized that the likelihood of developing such antibodies may be higher among women who have had children with more than 1 partner. Utilizing information on parenthood and breast cancer available in nationwide Swedish registers, we undertook a case-control study nested within a nation-wide cohort to address this issue. Number of partners fathering a child was categorized as 1, 2 and 3 or more. All analyses were restricted to subjects with 2 or more births and encompassed a total of 20,881 women with breast cancer and 111,989 control women. In an unadjusted analysis, the risk of breast cancer was somewhat lower (odds ratio [OR] = 0.94, 95% confidence interval [CI] 0.89-0.99) in women who had had children with 2 different partners compared with women who had had children conceived with the same partner. After adjustment for parity, age at first birth and educational level, however, the risk of breast cancer was slightly elevated (OR = 1.09, 95% CI: 1.03-1.15). Among women who had had children with 3 or more different men, the pattern was similar. The present results provide no support for the hypothesis that greater antigenic exposure afforded by having children with more than 1 man may reduce the risk of breast cancer. It remains possible, however, that pregnancy may influence breast cancer risk through some immunologic mechanism; further testing of the fetal antigen hypothesis may require development of relevant laboratory measures.

Adult↗

Socioeconomic factors affecting first marriage and birth rates by sex and age in the total Japanese population.

The effects of a wide variety of social, economic and demographic factors on age-specific first marriage and live birth rates in 46 Japanese prefectures were analyzed using stepwise regression analysis for 1970 and again for 1975 after classification of those twenty-two factors by factor analysis. The principal results were as follows: (1) high employment (high income) and social mobility caused by industrialization had a strongly positive influence on the first marriage and birth rates for young females, (2) rural and urban residence factors had positive effects on the marriage and birth rates for young males and females, respectively, (3) old age factor had an inverse effect on the marriage rates for both males and females over a wide range of ages, and (4) young age factor promoted the birth rate for young and middle-aged females. The characteristics of the first marriage and live birth rates in Japan were discussed in the light of these findings.

Adolescent↗

Features of infant exposure to tobacco smoke in a cohort study in Tasmania.

STUDY OBJECTIVES: To document changes in smoking style around infants over time and to identify factors associated with the smoking hygiene of mothers and others. DESIGN: A population based cohort study. SETTING: Population based, involving 22% of live births in Tasmania, Australia. PARTICIPANTS: From 1 May 1988 to 30 April, 1993, 6109 infants and their mothers (89% of eligible infants) participated in the hospital and home interview of the cohort study. Infants eligible for cohort entry were those assessed at birth to be at a higher risk of SIDS. MAIN RESULTS: The overall proportion of mothers who smoked during pregnancy and postnatally did not decline. Increasing trends were found for mothers and others not smoking in the same room as baby or while holding or feeding the baby, significant over the five year period. Good smoking hygiene (mother not smoking in the same room as baby) was positively associated with--first birth (OR = 1.74 (1.30, 2.33)), low birth weight (1.69 (1.27, 2.23)), being born after 1 May 1991 (1.67 (1.33, 2.11)), and private health insurance status (1.39 (1.02, 1.90)). Good smoking hygiene was negatively associated with maternal smoking during pregnancy (0.50 (0.31, 0.80)), intention to bottle feed (0.62 (0.49, 0.78)), the level of maternal postnatal smoking, increasing numbers of smokers in the household, and parents cohabiting but unmarried. A similar analysis was conducted for other household residents who smoked. CONCLUSIONS: Changes in maternal smoking prevalence have been small. The exposure of infants to tobacco smoke postnatally has decreased significantly, although a large proportion of infants are still exposed to tobacco smoke. The identification of the above parental and infant factors associated with good smoking hygiene should be useful for health education planning.

Cohort Studies↗

Population attributable fraction estimation for established breast cancer risk factors: considering the issues of high prevalence and unmodifiability.

Established breast cancer risk factors, in addition to being relatively unmodifiable, are highly prevalent among US women. Previous reports of population attributable fraction for the established risk factors have used definitions that resulted in 75-100% of women in the source population labeled exposed. The practical value of such estimates has not been discussed; further, the estimates have frequently been misinterpreted. In the context of examining the interpretation and public health value of such estimates, the authors demonstrate the sensitivity of the population attributable fraction to changes in exposure cutpoints. They use data from the Carolina Breast Cancer Study, a case-control study of breast cancer conducted in North Carolina between 1993 and 1996. For the four established risk factors (menarche before age 14 years, first birth at age 20 years or later/nulliparity, family history of breast cancer, and history of benign breast biopsy), the estimated population attributable fraction was 0.25 (95% confidence interval 0.06-0.48). Over 98% of the source population was exposed to at least one of these risk factors. The population attributable fraction estimate was reduced to 0.15 when more restrictive definitions of early menarche (less than age 12 years) and late age at first full-term pregnancy (30 years or more) were used (proportion exposed, 0.62). Population attributable fractions for established breast cancer risk factors probably have little public health value because of both the high proportions exposed and the relative unmodifiability of the risk factor distributions.

Adolescent↗

Smoking prevalence of pregnant women compared to women in the general population of Washington State.

We used two readily available sources of information to identify subgroups of pregnant Washington State women with high smoking rates. We compared smoking rates in pregnant women and women in general using information from the Washington State birth certificate collection system and the Washington State Behavioral Risk Factor Surveillance System. Smoking rates are substantially higher in young mothers 18-24 years of age than in comparable age cohorts in the general population of women in the state. In contrast, mothers 25 years of age and older smoke at lower rates than their age cohort in the general population. For multiparous women of all ages, smoking prevalence is related to age at first birth. Married women, whether pregnant or not, smoked less than unmarried women.

Adolescent↗

The development of stimulation-produced analgesia (SPA) in the rat.

The present study studied the development of stimulation produced analgesia (SPA) from the periaqueductal gray (PAG) in rats. A monopolar stimulating electrode was lowered into the dorsal or ventral PAG of animals aged 7, 14, 21, or 90-120 days. Constant current cathodal pulses (100 Hz, 100 microseconds) were delivered, starting 10 s before analgesia was tested by the tail-flick (TF) test and continuing throughout each TF trial or until cut-off (7 s). Current intensity was increased stepwise (3-200 microA). It was found that SPA can be elicited starting at 21 days, but not earlier. However, supraspinal modulation of nociception is still immature at 3 weeks after birth. First, stimulation intensities needed to produce SPA are higher in 21-day-old pups than in adult animals. Second, in 21-day-old pups, but not in adults effective current intensities in the dorsal PAG are higher than in the ventral PAG. Third, naltrexone decreases SPA from the ventral PAG in 21-day-old pups, but not in adult animals. These findings indicate that supraspinal modulation of nociception develops only 3 weeks after birth, with the ventral PAG maturing prior to the dorsal PAG, and that the contribution of endogenous opioids to SPA does not remain constant throughout the ontogeny of rats.

Aging↗

Getting a piece of the pie? The economic boom of the 1990s and declining teen birth rates in the United States.

In the United States, the 1990s was a decade of dramatic economic growth as well as a period characterized by substantial declines in teenage childbearing. This study examines whether falling teen fertility rates during the 1990s were responsive to expanding employment opportunities and whether the implementation of the Personal Responsibility and Work Opportunities Act (PRWORA), increasing rates of incarceration, or restrictive abortion policies may have affected this association. Fixed-effects Poisson regression models were estimated to assess the relationship between age-specific birth rates and state-specific unemployment rates from 1990 to 1999 for Black and White females aged 10-29. Falling unemployment rates in the 1990s were associated with decreased childbearing among African-American women aged 15-24, but were largely unrelated to declines in fertility for Whites. For 18-19 year-old African-Americans, the group for whom teen childbearing is most normative, our model accounted for 85% of the decrease in rates of first births. Young Black women, especially older teens, may have adjusted their reproductive behavior to take advantage of expanded labor market opportunities.

Adolescent↗

Prenatal influences on brain dopamine and their relevance to the rising incidence of autism.

The incidence of autism has risen 10-fold since the early 1980s, with most of this rise not explainable by changing diagnostic criteria. The rise in autism is paradoxical in that autism is considered to be one of the most genetically determined of the major neurodevelopmental disorders and should accordingly either be stable or even declining. Because a variety of epigenetic influences, particularly those occurring during the prenatal period, can override or masquerade as genetic influences, these should be considered as prime contributors to the recent increase of autism. Prenatal influences on dopamine activity are especially well-documented, including the effects of maternal psychosocial stress, maternal fever, maternal genetic and hormonal status, use of certain medications, urban birth, and fetal hypoxia. All of these factors have been implicated in the genesis of autism, which is characterized by a "hyperdopaminergic" state based on evidence from monkey and human behavioral studies, pharmacological studies in humans, and a left-hemispheric predominance of both dopamine and autistic-like symptoms. Chronically high maternal levels of dopamine caused by the pressures of increasingly urbanized societies and by changing maternal demographics such as increased workforce participation, educational achievement level, and age at first birth, may be especially significant epigenetic contributors to the recent autism rise.

Autistic Disorder↗

Birth control: some experiences from Denmark.

This article discusses that an effective birth control exists in Denmark today. Birth control is considered as a means for the couple not only to reach the wished-for family size by limiting their number of children but also to decide when to have children. Since 1973, women in Denmark can have an induced abortion on request before the end of the 12th week of pregnancy. An increasing proportion of women applying for induced abortion have no children, indicating that induced abortion is a means to obtain an effective postponement of first birth. The paper concludes that birth control is primarily accomplished by use of contraceptives and as an effect of widespread use, teenagers have managed to diminish their total rate of pregnancy rather dramatically.

Abortion, Induced↗

Cryptorchidism: a registry based study in Sweden on some factors of possible aetiological importance.

STUDY OBJECTIVE: To examine the epidemiological characteristics of boys with cryptorchidism. DESIGN: Cohort survey using the Swedish personal identification code and Medical Birth Registry to link cryptorchid boys with their pregnancy and delivery data. They were compared with the total population of male births during the same period. SUBJECTS: 2861 cryptorchid boys born in Sweden between 1973 and 1982 were identified. Of these 437 could not be linked with their Medical Birth Registry information for various reasons, or were excluded because they were under 1 year of age at the end of 1982, leaving 2424 cases for study. The reference population comprised all boys born in Sweden during the same period (n = 458,601). MEASUREMENTS AND MAIN RESULTS: For each study variable, the observed number of cases among boys with cryptorchidism was compared with the expected number calculated from the whole population. A significant increase in intensity ratio for cryptorchidism was found with the first birth, caesarean section, toxaemia of pregnancy, and certain congenital abnormalities (hypospadias and subluxation of the hip). It was also more common in small for dates infants. There was a seasonal variation in cryptorchidism, with increased incidence in January-March. CONCLUSIONS: Cryptorchidism may be caused by hormonal influences during pregnancy, which could be affected by utero-placental factors involving placental dysfunction or by daylight hours, through pineal activity.

Birth Certificates↗