First Birth In Women Research Articles

Correlates of age at first birth among women in Ethiopia: use of multilevel survival analysis models.

the timing of birth of the first child has a direct relationship with fertility in general and health and future career including further education of a mother in particular. The objective of this study was to identify factors significantly associated with the time to the first birth among women in Ethiopia. a cross-sectional study was conducted using data from the 2016 Ethiopian Demographic and Health Survey (EDHS). The study subjects were married women and men aged 15 to 49 in randomly selected households across Ethiopia and two stage stratified random sampling technique was used to select study subjects. Log logistic-Gamma shared frailty model was used to identify factors associated with the length of time spent until the first birth. the median age at first birth for women living in Ethiopia was 20 years, whereas the minimum and maximum ages at first birth were 11 and 49 years respectively. Age at first sex, age at first cohabitation, sex of household head, place of residence, religion, education level, contraceptive use and exposure to media were significant correlates of age at first birth of women in Ethiopia. Higher level of education was associated with increased age at first birth. Women who use contraceptive, women living in urban areas, women having exposure to media and female headed households had longer time to first birth compared to their counterparts. the different regions of Ethiopia have significant differences in the age of women during their first birth. Most of the factors associated with the time to first child in this study were related to education of women. Investing in education and educating women plays critical roles in regulating fertility of a nation and health of women.

Patterns and determinants of age at first birth of women in Myanmar

Fertility rates vary significantly across different socioeconomic and demographic factors, customs, cultures and practices of people living in different parts of the world. The age at first birth, one of the most significant events in a woman’s life, is directly and indirectly related to total fertility. The present paper is focused on the patterns, and socioeconomic and demographic determinants of age at the first birth of Myanmar women. For this study, data from the Myanmar Demographic and Health Survey 2015–2016 were used. A total of 7,613 ever-married women between 15 and 49 years who had given birth participated in the survey. The pattern of women at first birth was estimated using as descriptive technique and the determinants of age at first birth were identified using the Cox Proportional Hazards model. The average age at first birth of Myanmar women was 22.4 years in 2015-2016. The results of this study indicate that women’s education level and their age when they first engaged in sex, birth cohort, wealth index, residence, husband’s education and occupation whether they reside in a female-headed household were found to be significant factors associated with age at first birth. The age of women at first birth tended to be longer for women living in urban areas and women married to men with high degrees of education. Based on the results of this study, rural areas need to be developed and improving educational attainment is required to delay the age at first birth of women in Myanmar.

The role of dispersal and school attendance on reproductive dynamics in small, dispersed populations: Choyeros of Baja California Sur, Mexico.

Individuals from small populations face challenges to initiating reproduction because stochastic demographic processes create local mate scarcity. In response, flexible dispersal patterns that facilitate the movement of individuals across groups have been argued to reduce mate search costs and inbreeding depression. Furthermore, factors that aggregate dispersed peoples, such as rural schools, could lower mate search costs through expansion of mating markets. However, research suggests that dispersal and school attendance are costly to fertility, causing individuals to delay marriage and reproduction. Here, we investigate the role of dispersal and school attendance on marriage and reproductive outcomes using a sample of 54 married couples from four small, dispersed ranching communities in Baja California Sur, Mexico. Our analyses yield three sets of results that challenge conventional expectations. First, we find no evidence that dispersal is associated with later age at marriage or first reproduction for women. For men, dispersal is associated with younger ages of marriage than those who stay in their natal area. Second, in contrast to research suggesting that dispersal decreases inbreeding, we find that female dispersal is associated with an increase in genetic relatedness among marriage partners. This finding suggests that human dispersal promotes female social support from genetic kin in novel locales for raising offspring. Third, counter to typical results on the role of education on reproductive timing, school attendance is associated with younger age at marriage for men and younger age at first birth for women. While we temper causal interpretations and claims of generalizability beyond our study site given our small sample sizes (a feature of small populations), we nonetheless argue that factors like dispersal and school attendance, which are typically associated with delayed reproduction in large population, may actually lower mate search costs in small, dispersed populations with minimal access to labor markets.

Symptoms of fecal incontinence two decades after no, one, or two obstetrical anal sphincter injuries

The long-term effects of 1 or 2 consecutive obstetrical anal sphincter injuries on bowel continence are still inadequately investigated, and published results remain contradictory. This study aimed to present detailed descriptive measures of the current bowel incontinence 20 years after the first birth in women who had 2 vaginal deliveries with and without sphincter injuries. Birth register data were used prospectively and linked to information from a questionnaire survey about current symptoms. Women with 2 singleton vaginal births, from 1992 to 1998, and no further births were retrieved and surveyed by the Swedish Medical Birth Register and Statistics Sweden in 2015. A simple random sample of 11,000 women was drawn from a source cohort of 64,687 women. The cumulative effect was studied in all women with a repeat sphincter injury from 1987 to 2000. Postal and web-based questionnaires were used. The study population consisted of 6760 women with no sphincter injury, 357 with 1 sphincter injury, and 324 women with 2 sphincter injuries. Women with 2 deliveries without sphincter injuries aged 40 to 60 years as reference, were compared with those of women that sustained 1 or 2 consecutive sphincter injuries. Here, third- and fourth-degree perineal tears were presented as 1 group. Fecal incontinence was defined as current involuntary leakage of solid or liquid stool, with and without concomitant leakage of gas. The Fisher exact test and the Mann-Whitney U test were used to compare the results of the 2 groups. The trend was analyzed using the Mantel-Haenszel statistics. Logistic regression models obtained the estimated age-related probability of fecal incontinence components. The risk of sphincter injury at first delivery was 3.9%, and the risk of a repeat sphincter injury was 10.0% (odds ratio, 2.70; 95% confidence interval, 1.80-4.07). The overall prevalence of fecal incontinence in women without sphincter injuries was 11.7%, which doubled to 23.8% (odds ratio, 2.27; 95% confidence interval, 1.75-2.94) in those with 1 sphincter injury and more than tripled to 36.1% (odds ratio, 3.97; 95% confidence interval, 3.11-5.07) after 2 sphincter injuries (trend P<.0001). The proportion of women with severe fecal incontinence increased 3-fold and 5-fold from 1.8% after no obstetrical anal sphincter injury to 5.4% (95% confidence interval, 3.3-8.2) and 9.0% (95% confidence interval, 6.1-12.6) after 1 or 2 obstetrical anal sphincter injuries, respectively (trend P<.0001). In women without sphincter injuries, the estimated probability of fecal incontinence increased from 7.0% at the age of 40 years to 19.8% at the age of 60 years. In contrast, in women with 1 or 2 sphincter injuries, the estimated probability of fecal incontinence increased from 26.1% and 33.3%, respectively, at the age of 40 years to 36.8% and 48.8% at the age of 60 years. The prevalence of fecal incontinence increased after 52 years of age in women with 1 or 2 sphincter injuries. The dominant types of leakage in women with fecal incontinence were the combination of liquid stool and gas, and the triple combination consisting of solid and liquid stools and gas. The triple combination increased from 18.9% in those without sphincter injury to 28.2% in women with 2 injuries (trend P=.0204). The risk of sustaining a repeat sphincter injury at the second delivery was almost tripled compared with the risk at the first delivery. Furthermore, 1 or 2 sphincter injuries brought severe long-term consequences for bowel continence. Accidental leakage of stool and gas increased with each sphincter injury, and the effect was proportionally cumulative. After the age of 52 years, the prevalence of fecal incontinence seemed to accelerate.

What shapes public attitudes towards assisted reproduction technologies in Europe?

By examining attitudes on assisted reproduction technologies (ART) in 42 European countries, we highlight individual and country-level factors that are associated with the level of social acceptance or rejection of ART. This paper contributes to the literature on social acceptance of artificial insemination and in-vitro fertilization, the two most prominent examples of ART in Europe, and directs attention to several previously under-researched aspects. The empirical base of this study is the fourth round of the European Values Study, conducted in 2008–2010. Using a multilevel random-intercept linear regression model, we examine the impact of several individual- and country-level characteristics on the agreement level with the statement that artificial insemination or in-vitro fertilization can always be justified, never be justified or it is evaulated in a mixed manner. According to our findings, there are strong relationships between attitudes towards ART and socio demographic variables, as well as religiousness and some individual attitudes, including those related to traditional family formation practices, “justification for homosexuality”, (non-)preference for homosexual neighbors and acceptance of adoption by homosexual couples. For country-level characteristics we find significant association only in the case of mean age at first birth of women. We do not find a significant relationship between attitudes towards ART and country-level variables such as GDP, religiosity and same-sex couples’ access to ART.

Age at first birth in women is genetically associated with increased risk of schizophrenia

Previous studies have shown an increased risk for mental health problems in children born to both younger and older parents compared to children of average-aged parents. We previously used a novel design to reveal a latent mechanism of genetic association between schizophrenia and age at first birth in women (AFB). Here, we use independent data from the UK Biobank (N = 38,892) to replicate the finding of an association between predicted genetic risk of schizophrenia and AFB in women, and to estimate the genetic correlation between schizophrenia and AFB in women stratified into younger and older groups. We find evidence for an association between predicted genetic risk of schizophrenia and AFB in women (P-value = 1.12E-05), and we show genetic heterogeneity between younger and older AFB groups (P-value = 3.45E-03). The genetic correlation between schizophrenia and AFB in the younger AFB group is −0.16 (SE = 0.04) while that between schizophrenia and AFB in the older AFB group is 0.14 (SE = 0.08). Our results suggest that early, and perhaps also late, age at first birth in women is associated with increased genetic risk for schizophrenia in the UK Biobank sample. These findings contribute new insights into factors contributing to the complex bio-social risk architecture underpinning the association between parental age and offspring mental health.

Why after 50 years of effective contraception do we still have unintended pregnancy? A European perspective.

Unintended pregnancy is a public health concern throughout Europe. There is no common definition and no standard way to measure unintended pregnancy. Identifying unintended births is difficult and prevalence estimates vary depending on how and when the question is asked. Abortion rates are not a proxy and are themselves notoriously inaccurate. An estimated 34% (in Western Europe) to 54% (in Eastern Europe) of pregnancies are unintended. The determinants of unintended pregnancy are the length of the reproductive span and exposure to the risk of conception; the desired number of children and contraceptive use and effectiveness. The age of sexual debut fell during the 20th century in Europe to between 15 and 18 years of age. Mean age at first birth for women is now over 30 years in most European countries and most couples want no more than two children. Thus most couples must use contraception perfectly for many years in order to avoid unintended pregnancy. Use of effective contraception is high throughout most of Europe but there is scope, through better provision of sexual health services, better formal sex education and better training of providers, to increase the uptake of the most effective contraceptives and improve use of all methods. For individual women unintended pregnancy can be a disaster and recourse to induced abortion should be freely available.

Abstract P6-08-24: Reproductive status and clinical pathological characteristics of young women diagnosed with breast cancer in Latin America: LACOG 0414 study

Abstract BACKGROUND Approximately 7% of women diagnosed with breast cancer (BC) are under 40 years old. Chemotherapy may adversely affect ovarian function therefore fertility is an issue to be addressed for these patients. Patients with cancer in Latin America have limited access to fertility preservation. However age at first birth in women from Latin America is lower than in developed country and the needs of fertility preservation may be different from developed countries. The aim of the present study was to describe the reproductive status and clinical pathological features of young women diagnosed with BC in Latin America. METHODS LACOG 0414 is a prospective registry in Latin America which included young patients with &amp;lt; 40 years old with diagnosis of BC and indication of (neo) adjuvant chemotherapy. Demographic data, reproductive status and clinical pathological information were retrieved from patients` medical charts. This study was approved by local ethics committees and regulatory authorities. RESULTS A total of 343 patients (pts) from 19 different sites distributed in 4 Latin American countries were included: Brasil (N=132 pts), Mexico (N=112 pts), Peru (N=83 pts) and Cuba (N=16 pts). The mean age at BC diagnosis was 34.02 (±4.17) years (14% had &amp;lt; 30 years, 41% had 30-35 years and 44% had 36-40 years). From all included patients, 245 (71.42%) already had children at the time of BC diagnosis. From those the median number of children per women was 2 (range 1–6). The probability of having children at the time of diagnosis was significantly higher with increased age, being as high as 80% in those aged between 36 and 40 years old. There was no difference in terms of having a child at BC diagnosis within the 4 countries, by stage at diagnosis or per breast cancer subtypes. In terms of educational level, approximately 8% of patients were Illiterate and only 40% had university degree. Stages at BC diagnosis were the following: 12% stage I, 49% stage II, 35% stage III and 3% stage IV. The distribution of BC subtypes was: luminal 48%, HER2-positive 29% and triple negative 23%. CONCLUSION To our knowledge, this is the first study describing reproductive status of young patients diagnosed with BC in Latin America. Despite the lack of access to fertility preservation programs in the region, we found that a high number of patients had children at diagnosis of BC. Considering the high prevalence of advanced disease and aggressive subtypes the socioeconomic impact of young BC patients in Latin America needs to be addressed. Citation Format: Werutsky G, Villarreal-Garza C, Morante Cruz ZD, Debiasi M, Zaffaroni F, Fonseca A, Castro-Sánchez A, Platas A, Gómez Moreno H, Bretel D, Ortiz RM, Reinert T, Dybal V, Liedke P, Barrios C. Reproductive status and clinical pathological characteristics of young women diagnosed with breast cancer in Latin America: LACOG 0414 study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-08-24.

Variation in reproductive outcomes of women with histories of bulimia nervosa, anorexia nervosa, or eating disorder not otherwise specified relative to the general population and closest‐aged sisters

This study seeks to examine the long-term reproductive consequences of eating disorders (ED), to assess variation in reproductive outcomes by ED type, and to examine reproductive differences between women with previous ED diagnosis and their discordant sisters. Using a sample of women with previous ED diagnosis generated by the Utah Population Database, this study compares the fecundity (parity) and age at first birth of women by ED subtype (bulimia nervosa [BN], anorexia nervosa [AN], and ED not otherwise specified [EDNOS]) (n = 1,579). We also employed general population match case-control, and discordant sibling pair analyses, to estimate the magnitude of association between EDs and reproductive outcomes. Women previously diagnosed with AN or EDNOS experienced delayed first birth (HRR = 0.33, HRR = 0.34, respectively) and lower parity (IRR = 0.19, IRR = 0.22, respectively) relative to BN (p < .05), the general population (p < .05), and closest-aged sisters (p < .05). Women previously diagnosed with BN experienced more moderate reductions and delays to their reproduction, and had similar reproductive outcomes as their discordant sisters. Clinicians should consider ED type and family fertility histories when addressing the long-term reproductive health needs of women with prior AN, BN, or EDNOS diagnosis. Women previously diagnosed with AN or EDNOS likely experience the greatest reductions and delays in reproduction across their lifespan. Reproductive health screenings may be especially critical for the wellbeing of women with a history of AN or EDNOS.

DIFFERENTIAL RESPONSES IN FIRST BIRTH BEHAVIOUR TO ECONOMIC RECESSION IN THE UNITED KINGDOM.

Economic conditions have dramatic influences on fertility. This paper evaluates the effect of the 2008 'Great Recession' in the UK on first birth rate, which is the fertility behaviour most susceptible to external economic conditions. The key aim of the study was to assess the effect of the recession on fertility by individual-level characteristics, enabling variation in responses to economic hardship to be observed. Data were from the nationally representative UK Household Longitudinal Study (UK-HLS). Cumulative transition models were used to model the probability of first birth for women between the ages of 17 and 30 in three UK birth cohorts. The effect of the recession was captured using direct measures (local unemployment rates and individual unemployment status) and a pre-/post-comparison, capturing indirect effects. In general, higher birth rates were observed among more disadvantaged women compared with advantaged groups. The effect of the recession was disaggregated by social strata; the overall effect was counter-cyclical although at a slower rate among disadvantaged women.

Evidence for Genetic Overlap Between Schizophrenia and Age at First Birth in Women.

A recently published study of national data by McGrath et al in 2014 showed increased risk of schizophrenia (SCZ) in offspring associated with both early and delayed parental age, consistent with a U-shaped relationship. However, it remains unclear if the risk to the child is due to psychosocial factors associated with parental age or if those at higher risk for SCZ tend to have children at an earlier or later age. To determine if there is a genetic association between SCZ and age at first birth (AFB) using genetically informative but independently ascertained data sets. This investigation used multiple independent genome-wide association study data sets. The SCZ sample comprised 18 957 SCZ cases and 22 673 controls in a genome-wide association study from the second phase of the Psychiatric Genomics Consortium, and the AFB sample comprised 12 247 genotyped women measured for AFB from the following 4 community cohorts: Estonia (Estonian Genome Center Biobank, University of Tartu), the Netherlands (LifeLines Cohort Study), Sweden (Swedish Twin Registry), and the United Kingdom (TwinsUK). Schizophrenia genetic risk for each woman in the AFB community sample was estimated using genetic effects inferred from the SCZ genome-wide association study. We tested if SCZ genetic risk was a significant predictor of response variables based on published polynomial functions that described the relationship between maternal age and SCZ risk in offspring in Denmark. We substituted AFB for maternal age in these functions, one of which was corrected for the age of the father, and found that the fit was superior for the model without adjustment for the father's age. We observed a U-shaped relationship between SCZ risk and AFB in the community cohorts, consistent with the previously reported relationship between SCZ risk in offspring and maternal age when not adjusted for the age of the father. We confirmed that SCZ risk profile scores significantly predicted the response variables (coefficient of determination R2 = 1.1E-03, P = 4.1E-04), reflecting the published relationship between maternal age and SCZ risk in offspring by McGrath et al in 2014. This study provides evidence for a significant overlap between genetic factors associated with risk of SCZ and genetic factors associated with AFB. It has been reported that SCZ risk associated with increased maternal age is explained by the age of the father and that de novo mutations that occur more frequently in the germline of older men are the underlying causal mechanism. This explanation may need to be revised if, as suggested herein and if replicated in future studies, there is also increased genetic risk of SCZ in older mothers.

Human Development and the Fertility Reversal: A Spatially Centered Sub-national Examination in the US

Recent research has highlighted a profound reversal in the well-documented relationship between increasing development and falling fertility at a global scale. This reversal shows that the total fertility rates of the most developed nations in the world are actually increasing. The trend means different things. In some cases, it is simply a data product of the slowing average age at first birth for women in highly developed areas. For others, it is a cultural shift towards larger families in response to a surplus of economic resources. Using multiple data sources, this research examines this shift in the United States by examining levels of relative sub-national human development at the county level and associated relationships to county total fertility rates. Results highlight a non-linear relationship that suggests sub-national human development is related to sub-national variations in fertility behaviors similar to recent research on a global scale. The policy implications of such a reversal in fertility are very important for government officials and public policy makers as they move forward in addressing future issues associated with population aging, labor force turnover, and in the providing of services to youth.

The Statistical Distribution and Determinants of Mother’s Age at First Birth

The age at which child bearing begins, influences the number of children a woman bears throughout her reproductive period in the absence of any active fertility control. This study employed both parametric and non-parametric survival analysis techniques, with a cohort of women within the reproductive age (15-49 years), to determine the statistical distribution of the age at first birth of a woman from her time of birth and identify the significant prognostic factors determining the timing of first birth of Ghanaian women. Using data from the Ghana Demographic and Health Survey (GDHS), the study fitted several parametric Accelerated Failure Time models, from which the best parametric distribution for age at first birth was selected. The results revealed that, the average age at first birth was about 20 years, with more than 87.4% of the women having giving birth before they attained 25 years of age. The age at first birth among the Ghanaian women was best modeled by the log-logistic model. By this model, the age at which a woman had her first birth was determined, at the 10% significance level, by her Age at first marriage, her Educational level, her Wealth Status and whether or not the women practiced family planning before their first birth.

Do women delay family formation in expensive housing markets?

BACKGROUNDRecent research by demographers and economists has examined the link between living costs and fertility outcomes. The literature has provided some evidence that high rents, or high housing costs, discourage fertility.OBJECTIVEI re-examine the hypothesis that delayed fertility (age at first birth) is related to the costs of housing measured either as rents or sales prices.METHODSI use data from the American Community Survey for 2006–2008 to construct mean age at first birth for women in a sample of 25 US metropolitan areas stratified by rents and sales prices. The sales prices for those metropolitan areas were from the National Association of Realtors. I use models of both aggregate relationships of mean age at first birth and metropolitan housing cost level measures and individual analyses of mean age and measures of ethnicity, education and labor force participation.RESULTSThe effect of being in an expensive housing market is a delay of first births by three to four years, after controlling for education, ethnicity and labor market participation. However, the relatively modest fit of individual models suggest that while the housing market may play a role it is also clear that there is a complex structure to the decision- making around fertility, labor force participation and housing market entry. Overall completed fertility does not appear to be changed.

Pregnancy and delivery in women with chronic inflammatory arthritides with a specific focus on first birth

To examine possible associations between chronic inflammatory arthritides and pregnancy outcomes with separate analyses of first and subsequent births before and after diagnosis. Linkage of data from a registry of patients with chronic inflammatory arthritides and the Medical Birth Registry of Norway enabled a comparison of pregnancy outcomes in women with chronic inflammatory arthritides and pregnancy outcomes in reference subjects. Outcomes of first birth and subsequent births before and after diagnosis were analyzed separately. Associations between chronic inflammatory arthritides and the women's health during pregnancy and delivery as well as perinatal outcomes were assessed in logistic regression analyses with adjustments for maternal age at delivery and gestational age. We analyzed 128 first births and 151 subsequent births after diagnosis and 286 first births and 262 subsequent births before diagnosis in patients and compared them with first and subsequent births in reference subjects. Firstborn children of women diagnosed as having chronic inflammatory arthritides were more often preterm (odds ratio [OR] 1.85 [95% confidence interval (95% CI) 1.09-3.13]) and small for gestational age (OR 1.60 [95% CI 1.00-2.56]). They also had lower mean birth weight (P=0.01) and higher perinatal mortality (OR 3.26 [95% CI 1.04-10.24]). Birth by caesarean section (all classifications) was more frequent in patients than in reference subjects, and elective caesarean section was 2-fold more frequent in patients, both in first birth (OR 2.60 [95% CI 1.43-4.75]) and in subsequent births (OR 2.18 [95% CI 1.33-3.58]). No excess risks of clinical importance were observed prior to diagnosis of chronic inflammatory arthritides. Excess risks were related to first birth in women diagnosed as having chronic inflammatory arthritides, including a higher rate of perinatal mortality. A higher caesarean section rate was related to all patient deliveries. Mainly, pregnancy outcomes before diagnosis did not differ from those in reference subjects.

Fertility history and cause-specific mortality: A register-based analysis of complete cohorts of Norwegian women and men

The relationship between women's reproductive histories and later all-cause mortality has been investigated in several studies, with mixed results. Some studies have also considered cause-specific mortality and some have included men, but none has done both. We analyse associations between parity and age of first birth for women and men across 11 cause-of-death groupings using Norwegian register data for complete cohorts born 1935-1968 whose mortality was observed 1980-2003 (i.e. at ages 45-68). Age, period, educational level, marital status, region of residence and population size of municipality were included as co-variates. In total, there were 63,000 deaths. Results showed that relative to parents of two children, childless men and women and those with one child had higher mortality risks for nearly all cause of death groupings. High parity (4+ children) was associated with raised male mortality from accidents and violence and higher mortality from cancer of the cervix among women. For other cause and gender groupings there was either little difference between those with two children and those of higher parities or an overall negative association between parity and mortality. Among men with the lowest level of education, however, high parity was positively associated with mortality from circulatory diseases. For all causes except female breast cancer, there was an inverse association between age at first birth and mortality risk. Similarities observed across cause groups and for women and men suggest that much of the fertility-mortality relationship is a result of selection or effects of reproductive behaviour on lifestyle. The latter may include both beneficial effects and harmful stress responses. However, physiological mechanisms are most probably important for some causes of death for women. Research on associations between parenting histories, health related behaviours, social support exchanges and reported or measured stress is needed to clarify mechanisms underlying the associations reported here.

An evolutionary model of stature, age at first birth and reproductive success in Gambian women.

We have built a model to predict optimal age at first birth for women in a natural fertility population. The only existing fully evolutionary model, based on Ache hunter-gatherers, argues that as women gain weight, their fertility (rate of giving birth) increases-thus age at first birth represents a trade-off between time allocated to weight gain and greater fertility when mature. We identify the life-history implications of female age at first birth in a Gambian population, using uniquely detailed longitudinal data collected from 1950 to date. We use height rather than weight as an indicator of growth as it is more strongly correlated with age at first birth. Stature does not greatly influence fertility in this population but has a significant effect on offspring mortality. We model age at first reproduction as a trade-off between the time spent growing and reduced infant mortality after maturation. Parameters derived from this population are fitted to show that the predicted optimal mean age of first birth, which maximizes reproductive success, is 18 years, very close to that observed. The reaction norm associated with variation in growth rate during childhood also satisfactorily predicts the variation in age at first birth.

Excess gains in weight and waist circumference associated with childbearing: The Coronary Artery Risk Development in Young Adults Study (CARDIA).

To examine the association of childbearing with weight and waist circumference (WC) changes, we compared women with and without pregnancies or births during follow-up. A multicenter, longitudinal observational study over 10 years. Comparison groups defined by the number of pregnancies and births during follow-up: P0 (0 pregnancies; nongravid), P1 (1+ miscarriages or abortions; 'short' pregnancies), B1 (1 birth), and B2 (2+ births). Mean changes in weight and WC for P1, B1 and B2 groups vs P0 were examined separately by race (black and white), baseline parity (nulliparous and parous) and baseline weight status (normal weight; BMI <25 kg/m(2) and overweight; BMI >/=25 kg/m(2)). A population-based sample of 2070 women aged 18-30 y at baseline (1053 black subjects and 1017 white subjects) from Birmingham, Alabama, Chicago, Illinois, Minneapolis, Minnesota, and Oakland, California were examined five times between 1985-1986 and 1995-1996. Weight and WC measurements were obtained using standardized protocol at baseline and examinations at years 2, 5, 7 and 10. Sociodemographic, reproductive, and behavioral attributes were assessed at baseline and follow-up examinations. Gains in weight and WC associated with pregnancy and childbearing varied by race (P<0.001), baseline parity (P<0.05) and overweight status (P<0.001). Among overweight nulliparas, excess gains in weight (black subjects: 3-5 kg, white subjects: 5-6 kg) and WC (black subjects: 3-4 cm, white subjects: 5-6 cm) were associated with 'short' pregnancies and one or more birth(s) during follow-up compared to no pregnancies (P<0.01 and 0.001). Among normal weight nulliparas, excess gains in weight (about 1 kg) and WC (2-3 cm) were associated with follow-up birth(s) (P<0.05). Among women parous at baseline, no excess weight gains were found, but excess WC gains (2-4 cm) were associated with follow-up births. Substantial excess weight gain is associated with both short pregnancies and a first birth in women overweight prior to initiation of childbearing. Excess weight gain was not associated with higher order births. Increases in waist girth were cumulative with both first and higher order births among overweight as well as normal weight women. Interventions to prevent obesity should be targeted at women who are overweight prior to initiation of childbearing. The impact of excess WC gains associated with childbearing on women's future health risk should be evaluated further.

Deferment of the First Birth and Fluctuating Fertility in Sweden

In Sweden, as in other industrialized countries, a decades-old decline in fertility rates has been accompanied by a rise in the age at first birth. In contrast to other industrialized countries, however, fertility rates rose sharply in the 1980s before plummeting in the 1990s. In this paper we apply hazard regression to data from the 1992 Swedish Family Survey, supplemented by annual earnings data linked to individuals and by annual time series of national-level economic indicators, to investigate the predictors of the timing of the first birth of women in Sweden since the mid-1960s. The discovery that both individual characteristics and aggregate-level factors influence the timing of the first birth casts light on both the continuing trend of postponement of the first birth and annual fluctuations in first-birth rates.

The spacing of births among French-Canadian families: an historical approach.

Utilisant la généalogie d'une seule famille‐souche canadienne‐française de 1650 à 1950, l'auteur compare l'intervalle entre les naissances dans la branehe canadienne et dans la branche américaine de cette famille. Indépendamment de la taille des families, l'intervalle s'accroit au cours des ans du côté américain. Une croissance de l'espacement ne se produit pas, par ailleurs, du côté canadien. II appert done que l'espacement progressif des naissances ne se produit que parmi les couples américains et que le comportement de ceux‐ci diffère de celui des couples canadiens. La présente recherche a pour but secondaire de mettre en lumière l'utilité des généalogies en démographie, particulièrement dans l'étude de la fécondité. La comparaison des résultats obtenus ici avec ceux qui proviennent d'autres études de l'espacement des naissances illustre l'usage que Ton peut f aire de telles données historiques: on a utilisé en l'occurrence les régistres ayant trait à une seule famille pendant trois siècles. Cette famille n'est pas nécessaire‐ment représentative de la famille canadienne‐francaise. II s'agit plutôt de l'étude démographique d'un cas familial dans le temps et dans l'espace.