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PubMedDate not supplied

Age at first birth in Canada: a hazards model analysis.

Studies on age at 1st birth and its covariates are few in the demographic literature on Canada, mainly due to the paucity of maternity history data. This is the 1st paper on this aspect of fertility, based on the data collected through the Canadian Fertility Survey in 1984 by Balakrishnan and colleagues. Since the majority of childbearing in Canada is still within marriage, this study focuses on ever-married women in the prime reproductive ages, 18-49, in 1984. To circumvent the problems of selectivity and censoring in the analysis of retrospective maternity history collected in a cross-sectional survey, the authors have chosen Cox's proportional hazards model for multivariate analysis for each of the age cohorts, viz. 18-24, 25-29, 30-34, 35-39, 40-44, and 45-49. As the focus is on the 1st birth, women 35 years of age and over can be viewed as having sufficient time for the 1st birth and thus as different from younger age cohorts. Separate analyses for different age groups is done to achieve greater homogeneity of covariate effects. The results indicate that ever married women with lower ages at marriage, premarital pregnancy, low education, not working, and nonuse of contraception before the 1st pregnancy are the potential early family starters. The significance of covariate effects varied for different age cohorts. Also presented are estimates of relative risks of the 1st birth by various combinations of covariates, ranging from high risk to low risk groups utilizing the baseline survival function obtained from the proportional hazards model.

Age Factors↗
PubMed1989

Age at first marriage and age at first birth.

This paper presents findings on patterns of age of 1st marriage and age of 1st birth for 41 countries participating in the World Fertility Survey program. The age distribution of 1st marriage and 1st birth is summarized with 3 statistics: the mean, the standard deviation, and the proportion ever experiencing the event. The particular method of estimation is based on a model that ensures that estimates for all cohorts are comparable, even though some women have completed their reproductive experience while others have not. The analysis provides insights into sources of error in the reporting of age at 1st birth. In addition, trends and cross-country patterns are documented and conclusions are drawn about the adequacy of these statistics for the description of patterns of age at 1st birth and age at 1st marriage.

Age Factors↗
PubMed1989

Trends and variations in first births to older women, United States, 1970-86.

Trends and variations in first-time childbearing women in their thirties and older are presented for the years 1970-86. The report focuses on the decline in childbearing by women in their twenties, particularly well-educated women, and the extent to which these women have delayed motherhood. Maternal and infant health characteristics are also discussed. The information presented is drawn from the live birth certificates of all states and the District of Columbia.

Adult↗
PubMed2006

First-birth outcomes and timing of second births: a statewide case management program for adolescent mothers.

This study examines a case management intervention for first-time pregnant and parenting adolescents. It compares a sample of 1,260 first-time adolescent mothers in the Adolescent Parenting Program (APP) in North Carolina with 1,260 first-time adolescent mothers who did not participate in the program (non-APP). Using birth certificate data, logistic regression and survival analyses were used to compare prenatal care use, birth outcomes, and subsequent births, adjusting for age, race, marital status, and tobacco use during pregnancy. The groups had similar rates of prenatal care use. Participation in APP, however, was associated with an increased likelihood of normal birthweight (more than 2,500 grams [5.5 pounds]) and full-term birth (at or more than 37 weeks). Adolescents ages 12 to 16 in the APP group also delayed second births significantly longer than the non-APP group. Study implications point to case management and direct services provided by social workers and health service professionals as instrumental to helping adolescent mothers achieve favorable birth outcomes and postpone subsequent births during adolescence.

Adolescent↗
PubMedDate not supplied

[Psychosocial stress as a risk factor for preterm birth--first results of the BabyCare project].

Psychosocial stress is and has been under study in a plenty of epidemiological research done to further detect the mechanisms between risk factors and preterm birth, but the role of these possible risk factors is up to now not approved neither theoretically nor empirically. Associations calculated between those risk factors and preterm birth are highly inconsistent and with exceptions only moderate. Based on the data given by the BabyCare programme in a first analysis for the group of primiparae it will be analysed, which psychosocial risk factors are correlated with preterm birth and which of these can be judged as independent risk factors, as far as this can be ruled out by the sample-size given. The descriptive data analysis shows, that the frequency of psychosocial risk factors is varying as it can be expected by age and social stratification. The analytical analysis shows by the given sample-size that the variable "strong stress in the last 12 months before pregnancy" has the highest ODDS-Ratio, which is also almost significant. Unexpectedly there is no correlation between preterm birth and the frequency and characteristics of life-events in the last 12 months, nor between the stress index, nor between the frequency of psychosocial complaints. Weaker associations--further to be approved--are given with respect to work load and occupation, problems in partnership and emotional or social support as well as to unplanned pregnancy and "low social status". The risk-ratios of the psychosocial variables are altogether much lower than the ratios of the medical or behavioural risk factors. The analysis of preterm birth rates reveals, that "strong stress in the last 12 months before pregnancy" will especially raise the preterm birth rates of smokers by an additional factor of 1.5. The associations found have to be approved by raising sample-size by stratified analytical methods and additional research by follow-up or retrospective studies to finally find out the factors which arise in the subsequent time of pregnancy and might explain the higher risk of preterm birth in the group of women with "strong stress in the last 12 months before pregnancy".

Female↗
PubMed2005

First births by age and education in Britain, France and Norway.

Progressively later starting of childbearing has been a feature of cohort change in fertility across Europe and elsewhere over recent decades. Growing differences in the age patterns of childbearing between the Anglo-American and continental European countries, however, have also been found. The present study uses large linked-record databases in Britain, France and Norway to analyse these differences in more detail, focussing on age at entry to motherhood (first childbearing) by level of educational attainment among women born in the 1950s and in the 1960s. The shift between these two cohorts towards a later pattern of first childbearing in Britain was confined to women with secondary school qualifications and above. For women born in the 1960s, the peak age for risk of first childbearing among those with secondary school qualifications grew to be between seven and eleven years later than among women without secondary school qualifications. In France and Norway, the peak ages for risk of first childbearing shifted more uniformly across education levels between the two cohorts. For these 1950s and 1960s cohorts, improvements in women's educational levels also occurred more uniformly in France and Norway, moving more women into education categories characterised by later patterns of first childbearing.

Adolescent↗
PubMed1998

The first births and ongoing pregnancies associated with sperm cryopreservation within evacuated egg zonae.

This new procedure principally aims to avoid a second or possibly multiple surgical procedures for sperm extraction from the male partner in cases of limited amounts of sperm cells, where normal freeze-thaw protocols would fail. Patients (n = 34) diagnosed as azoospermic, extreme oligozoospermic, or oligoasthenozoospermic underwent the process of sperm cryopreservation within evacuated egg zonae. Other samples were allocated to conventional sperm freezing. Sperm samples were acquired using testicular sperm extraction (TESE), microepididymal sperm aspiration (MESA), or fresh ejaculate. Subsequently, five of these 34 couples have undergone in-vitro fertilization (IVF) and achieved normal fertilization using post-thawed spermatozoa frozen under zonae pellucidae in conjunction with intracytoplasmic sperm injection (ICSI). The average fertilization rate for the post-thaw injected spermatozoa was 65%. This is comparable with the regular fertilization rate of 65% for combined MESA and TESE using fresh spermatozoa. All patients underwent embryo transfer. The average implantation rate per embryo was 31%; nearly the same for regular MESA/TESE ICSI cycles (32%). The first pregnancy associated with this procedure concluded with the full term delivery of healthy twin girls on July 18, 1997. The remaining four thaw procedures resulted in another twin delivery, an ongoing singleton gestation, a negative pregnancy test and a biochemical pregnancy respectively.

Adult↗
PubMed1981

Plasma prolactin levels and breast cancer: relation to parity, weight and height, and age at first birth.

Plasma prolactin has been measured in over 3,500 women volunteers from a normal population. In premenopausal women there was a significant decrease in prolactin levels with increasing parity. However, this effect was transitory since plasma prolactin concentration rose with increasing time after the birth of the last child. There were no significant differences in prolactin levels with respect to height and weight, although overweight compared to underweight women had approximately 15% more plasma prolactin. If prolactin is a carcinogen, then these results are in keeping with the epidemiological findings that multiparity affords protection and that age at last delivery is a risk factor in the development of breast cancer.

Adult↗
PubMed2003

Analysing cross-sectional data with time-dependent covariates: the case of age at first birth in South Africa.

Analysing time-dependent independent variables requires the use of process-oriented statistical models. Yet social scientists--especially those in poor countries--have often had to use data collected at a single point in time, making their task difficult. Making several assumptions about the covariates, the present study uses survival analysis and other statistical techniques to analyse the 1996 South African population census data and examine the effects of selected independent variables on the timing of parenthood in the country. It was found that the onset of parenthood occurs late in South Africa compared with the pattern in most other African societies. While education plays a role in the postponement of parenthood within racial groups, it fails to explain the differences between African and Coloured women on the one hand, and White and Asian women on the other hand, a finding that suggests the existence of two regimes of family formation in South African society.

Adolescent↗
PubMed1998

Like mother, like child: intergenerational patterns of age at first birth and associations with childhood and adolescent characteristics and adult outcomes in the second generation.

A 30-year follow-up of 1,758 inner-city children and their mothers in the Pathways to Adulthood Study revealed significant associations in transgenerational timing of age at 1st birth between mothers and their daughters and sons. Intergenerational age patterns were associated with the children's family and personal characteristics during childhood and adolescence and self-sufficiency at age 27-33. Continuity in teenage parenthood was associated with family and personal characteristics unfavorable for optimal child development and successful adult outcomes. Delay in 1st parenthood to age 25 or older was associated with significantly greater odds of more favorable environmental and developmental characteristics and greater adult self-sufficiency. The authors concluded that age at 1st birth of both mothers and children contributes, but in subtly different ways for daughters and sons, to the children's development and adult self-sufficiency.

Adolescent↗