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PubMed2000

Social-demographic influence on first birth interval in China, 1980-1992.

This study examines the delay between first marriage and first live birth in China among a sample of women who married between 1980 and 1992. Most couples in China only use contraception after the first child is born. Most sample women had their first child within 2 years of marriage. However, there are significant rural-urban differences in the first birth interval, indicating that there was most probably deliberate fertility regulation after marriage among many urban couples. Survival analysis shows that place of residence, level of education, age at first marriage and marriage cohort affect the first birth interval.

Adolescent↗
PubMed1992

Bladder cancer, parity, and age at first birth.

The excess of bladder cancer in males (M:F ratio of 4:1 in the United States) is not explained fully by gender differences in smoking habits or occupational exposures. Laboratory studies suggest that some androgenic hormones stimulate (or do not inhibit) oncogenesis in bladder tissue, and that estrogenic hormones have the opposite effect. These observations suggest that bladder cancer risk in females may be modified by sex hormones which undergo profound changes during and following pregnancy. Mail-questionnaire data from 317 incident female cases, and 833 population-based controls in Iowa were used to measure the effect of parity and maternal age at first birth on bladder cancer risk. Parous women were at decreased risk relative to nulliparous women (odds ratio [OR] = 0.67, 95 percent confidence interval [CI] = 0.44-1.00), after adjustment for age, tobacco use, and previous bladder infection. The overall risk reduction was restricted to women who had never smoked (OR = 0.51, CI = 0.30-0.88), with no apparent effect of parity among ever-smokers (OR = 0.93, CI = 0.49-1.77). Risk appeared to decrease with increasing age at first birth, but did not vary with increasing parity after the first birth. Our findings are consistent with the hypothesis that oncogenesis in transitional cell tissue of the human bladder is influenced by sex hormones, and that hormonal changes related to pregnancy thereby can decrease risk.

Adult↗
PubMed1987

A prospective study of age at menarche, parity, age at first birth, and coronary heart disease in women.

Reproductive events in women are associated with alterations in blood lipids and blood pressure and may therefore influence determinants of coronary heart disease. To investigate the risk of coronary heart disease in relation to age at menarche, parity, and age at first birth, the authors evaluated prospectively the experience of 119,963 US women aged 30-55 years who were free from coronary heart disease in 1976 and were followed through 1982. During 700,809 person-years of observation, 308 incident cases of nonfatal myocardial infarction or fatal coronary heart disease occurred. Younger age at menarche was weakly associated with coronary heart disease (age-adjusted rate ratio of 1.3 for menarche before age 11 years compared with menarche at age 13 years; chi, Mantel extension test for trend = -1.1, p = 0.2). Nulliparous women experienced only a slightly higher rate of coronary heart disease than parous women (rate ratio = 1.2, 95 per cent confidence interval 0.8-1.8). Among parous women, there was no alteration in risk with increasing number of births. Likewise, there was no significant association between age at first birth and coronary heart disease (chi, Mantel extension test for trend = -0.4, p = 0.4). Established risk factors for coronary heart disease nevertheless showed expected relations. These findings show no important association between reproductive experiences and risk of coronary heart disease.

Adult↗
PubMed1982

A cross-cultural examination of the relationship between ages at menarche, marriage, and first birth.

Recent work with samples of black and white urban American women showed a clear behavioral sequence relating age at menarche to age at first intercourse to age at first birth. This paper shows that the linking of ages at menarche, intercourse, marriage, and first birth is a pattern which occurs in very diverse cultures. We present confirmatory data from the United States, Belgium, and Pakistan, and from Malay and Chinese women in Malaysia. We interpret our findings as indicating a biological process leading to (a) social interpretations of readiness for reproduction, and (b) persisting biological differences between early and late maturing women.

Adolescent↗
PubMed1982

Race differences in age at first birth and the pace of subsequent fertility: implications for the minority group status hypothesis.

We examine race differences in the effects of age at first birth on the pace of subsequent fertility. If race differences in the pace of fertility persist net of age at first birth and socioeconomic variables, they will be taken as new support for the minority group status hypothesis. Data from the 1973 National Survey of Family Growth are analyzed with the finding that race differences in the pace of fertility are real, giving support to the hypothesis. Implications are drawn suggesting that the proper points at which to examine group differences in fertility are the different stages in the process which culminates in completed fertility, rather than limiting investigation to the final product.

Adolescent↗
PubMed1989

An extension of a model for first birth interval and some social factors.

"A model for the time of first birth is presented under certain assumptions, which involve biological and socio-cultural factors." The model is illustrated using data from Rural Development and Population Growth--A Sample Survey, 1978, conducted in Varanasi, India, and involving some 3,514 households.

Asia↗
PubMed2006

Marital decision-making and the timing of first birth in rural China before the 1990s.

Using a sample of couples drawn from the three provinces of Guangdong, Shandong, and Shaanxi, we investigated whether couples' increasing freedom to choose whom to marry influenced the timing of first birth in rural China during the four decades before the 1990s. The shortening of first-birth intervals in the period is found to be associated with the shift from arranged to free-choice marriages. The association is attributed largely to increased intimacy and coital frequency after marriage together with postponement of age at first marriage.

Age Factors↗
PubMed1989

Nulliparity, decade of first birth, and breast cancer in Connecticut cohorts, 1855 to 1945: an ecological study.

Risk of breast cancer increases with age at first birth, and is lower in women who bear their first children while young than in nulliparous women. While previous studies have investigated risk of breast cancer in birth cohorts by examining partial aspects of cohort childbearing, the present ecological study assesses total cohort childbearing risk in Connecticut women born between 1855 and 1945. In each cohort, the proportion of women nulliparous and first bearing children in their twenties, thirties, and forties are weighted by relative risks associated with these events as ascertained in previous studies. Summed cohort childbearing risks are compared to the incidence of breast cancer in women 40 years of age and older in the same cohorts. Changes in decade of first birth and nulliparity do not explain the changes in breast cancer incidence observed: while cohort childbearing risk has declined over the period examined, breast cancer incidence has increased in the same cohorts. Alternative explanations for cohort increases in breast cancer incidence are reviewed.

Breast Neoplasms↗
PubMed1991

[The suitable age for first-birth from the view of infant's health].

During March to June 1985, a health survey was carried out in a series of 963 infants of first-birth born in six hospitals in Changsha city. The health status of the infants was estimated by using the method of comprehensive score evaluation. The relationship between score and the mother's age was analysed. The results showed that the geometric mean of the score of the infants whose mother was 24-29 years old was lower than the infants whose mother was 19-23 years old or 30-38 years old. It indicated that the suitable age for first-birth was from 24 to 29 years old.

Adult↗
PubMed1978

Age and marital status at first birth and the pace of subsequent fertility.

Taking care to minimize the truncation bias inherent in cross-sectional data and controlling for other variables, this paper demonstrates the strong effects of both age and marital status at first birth on the pace of subsequent fertility. These effects are particularly strong in the interval immediately following the first birth but persist even into the fourth interval. Important differences are found with respect to the experience of rapid fertility, rather than in the mean lengths of intervals. These results add to the growing attention to the social dimensions of age as a variable in fertility processes.

Adolescent↗
PubMed1980

Nutrition and age at first birth in breast-cancer risk.

Urban/rural breast-cancer incidence ratios in the state of Iowa for 1950 and 1969-71 were contrasted with corresponding urban and rural distributions of age-at-first-birth and population nutrition, variable measured approximately 15 years before each morbidity survey and putatively related to breast-cancer incidence. Over the study interval, the decline in the urban/rural breast-cancer incidence ratio correlated better with changing nutritional patterns than with changing age-at-first-birth.

Adult↗
PubMed1983

Age at first birth, parity, and breast cancer risk.

The roles of age at first full-term birth and parity as risk factors for breast cancer were examined as part of a large prospective cohort study of oral contraceptive use. Compared to women who first gave birth before age 20 years, women with a first birth between age 20 and 24 years had an SRR of 1.70, and women with first births between age 25 and 29 years and over age 29 had SRRs of 2.19 and 3.18, respectively. Increased incidence rates of breast cancer fell with increasing parity, although standardization for age at first birth diminished the importance of the former as an independent indicator of breast cancer risk.

Adult↗
PubMed1983

Secular trends in the distributions of the breast cancer risk factors--menarche, first birth, menopause, and weight--in Hiroshima and Nagasaki, Japan.

The results of a mail survey completed by approximately 21,000 female atomic bomb survivors in Hiroshima and Nagasaki in 1970 are studied with respect to menarche, first birth, menopause, and weight. These known risk factors for breast cancer can be used to explain some but not all of the differences in Japanese and US breast cancer rates. The results for age at menarche are the most striking, with the presence of a strong secular trend. The average age at menarche in Japan was observed to decrease from 16.4 years for women born in 1902 to 14.4 years for women born in 1942. However, a temporary increase was observed in women whose menarche was expected to occur during the war years of the early 1940s. Differences between US and Japanese women were also observed in age at first birth and nulliparity rates. Age at menopause was similar for the two groups, although US women have a considerably higher rate of surgically induced menopause. Within each birth cohort, it is shown that body weight is negatively correlated with age at menarche and positively correlated with age at menopause.

Adult↗
PubMed2004

Long-term plasma lipid changes associated with a first birth: the Coronary Artery Risk Development in Young Adults study.

Previous studies have reported declines in high density lipoprotein (HDL) cholesterol 1-2 years after pregnancy. In 1986-1996, the authors prospectively examined the association between childbearing and changes in fasting plasma lipids (low density lipoprotein, HDL, and total cholesterol; triglycerides) among 1,952 US women (980 Black, 972 White) in the Coronary Artery Risk Development in Young Adults study. Repeated-measures multiple linear regression was used to examine lipid changes over three time intervals (baseline to years 5, 7, and 10) in time-dependent follow-up groups: P0 (0 pregnancies), P1 (>/=1 miscarriages/abortions), B1 (1 birth), and B2 (>/=2 births). Means stratified by race and baseline parity (nulliparous or parous) were fully adjusted for study center, time, height, baseline diet, and other baseline and time-dependent covariates (age, smoking, education, weight, waist circumference, alcohol intake, oral contraceptive use, physical activity, short pregnancies). For both races, fully adjusted HDL cholesterol declines of -3 to -4 mg/dl were associated with a first birth versus no pregnancies during follow-up (p < 0.001). Higher-order births were not associated with greater declines in HDL cholesterol (B2 similar to B1, no association among women parous at baseline). In Whites, total and low density lipoprotein cholesterol declines were associated with follow-up births. HDL cholesterol declines of -3 to -4 mg/dl after a first birth persisted during the 10 years of follow-up independent of weight, central adiposity, and selected behavior changes.

Adolescent↗
PubMed1991

The effect of imputation procedures on first birth intervals: evidence from five African fertility surveys.

In most African societies there is little motivation to remember dates of demographic events with the level of precision required in demographic surveys. Consequently it is common that the large majority of survey respondents can provide only the calendar year of occurrence or their age at the time of the event. The World Fertility Survey Group decided to handle the problem of poor date reporting by using a computer program to impute the missing information. This article illustrates the effect of these imputation procedures on cross-national differentials in the proportion of premarital first births in Benin, Cameroon, Côte d'Ivoire, Ghana, and Nigeria. The analysis demonstrates that the exceptionally low proportion of premarital first births in Ghana is an artifact of the imputation procedures.

Adolescent↗
PubMedDate not supplied

Waiting times to first birth in a rural area.

The waiting time between marriage and first birth is a particularly interesting parameter, for it reveals both the fertility of a given population as well as its social behaviour with regard to reproduction and the institution of marriage. Such waiting times were analysed in 289 nuclear families in the village of Chateauponsac, Limousin, France according to maternal marital age and social class. After correction for age effects, it was shown that women from the working class tended to have their first child much earlier than those in other occupational groups--often either before marriage or conceived prenuptially. It is concluded that this behaviour arises from economic factors rather than through differential use of contraceptives.

Adult↗
PubMed1986

Age at first birth and the length of the second birth interval: is a positive relationship universal in modern populations?

"Age at first birth has been found to be positively associated with the length of the second birth interval in several studies. One researcher has hypothesized that such a relationship would be found in any population in which contraception is widespread and women are exposed to non-maternal roles. However, in this study a positive relationship is not found for caucasian women in Hawaii, a population in which contraception is wide-spread and women are exposed to non-maternal roles. The findings suggest a revision of the hypothesis to accommodate more complex relationships."

Age Factors↗
PubMed1988

The impact of first-birth timing on divorce: new evidence from a longitudinal analysis based on the Central Population Register of Norway.

"The association between divorce risks in first marriage and the timing of the first birth is inspected in a life-table analysis of registered birth and marriage histories from Norway. One of the main conclusions is that the high propensity to divorce among women who have had a premarital birth is not confined to those who marry someone other than the father of their child. Also, women who have had a premarital child with their husband, run a much higher risk of marital breakup than do those who had their first baby in wedlock.... It is argued that couples who postpone childbearing beyond two years of marriage may have particularly low divorce rates." (SUMMARY IN FRE)

Birth Order↗