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PubMed1986

The determinants of effective fecundability based on the first birth interval.

There are substantial differences in fecundability among nine developing countries in different parts of the world. In addition, within countries, later age at marriage has a clear, positive, nonlinear effect on fecundability. Women with higher education and those with more educated husbands have higher fecundability. Urban residents have higher fecundability than rural. The higher fecundability of more recent cohorts is the most consistent observation. Since those variables most frequently shown to have inverse relationships to fertility show direct relationships to fecundability within populations, the role of fecundability as a proximate variable in models of the determinants of fertility requires further specification.

Adult↗
PubMed2001

Does the increased risk of preterm delivery in teenagers persist in pregnancies after the teenage period?

OBJECTIVE: To study the associations between low maternal age at first birth and the risks of very and moderately preterm birth, in first birth and in second successive birth in adulthood. DESIGN: Population-based cohort study. SETTING: Sweden. POPULATION Women aged less than 25 years at first birth (n = 275,933), having two successive live single births from 1973 through 1993. METHODS: Odds ratios with 95 percent confidence intervals were calculated to estimate the effect of low maternal age at first birth. Analyses of first births were adjusted for year of first birth and maternal education and in second births also for previous pregnancy outcomes and interpregnancy interval. MAIN OUTCOME MEASURES: Very preterm birth (less than 33 completed weeks) and moderately preterm birth (33-36 completed weeks). RESULTS: Compared with women aged 20 to 24 years at first birth, mothers aged 13 to 15 years were at increased risk of very preterm birth (odds ratio = 4.8). The corresponding risks among women aged 16 to 17 years at first birth were doubled (odds ratio = 2.3). The influence of maternal age on risks of moderately preterm birth was similar, although the age-related risks were lower. At second birth, risks of preterm birth were reduced in all age groups. However, mothers who were 17 years or less at first birth, faced, compared with mothers aged 20-24 years, significantly larger reduction in risks of very and moderately preterm birth. CONCLUSIONS: Our results suggest that there may be a biological effect of very young maternal age, affecting foremost very preterm birth.

Adolescent↗
PubMed2001

Maternal periodontitis and prematurity. Part I: Obstetric outcome of prematurity and growth restriction.

Oral Conditions and Pregnancy (OCAP) is a 5-year prospective study of pregnant women designed to determine whether maternal periodontal disease contributes to the risk for prematurity and growth restriction in the presence of traditional obstetric risk factors. Full-mouth periodontal examinations were conducted at enrollment (prior to 26 weeks gestational age) and again within 48 hours postpartum to assess changes in periodontal status during pregnancy. Maternal periodontal disease status at antepartum, using a 3-level disease classification (health, mild, moderate-severe) as well as incident periodontal disease progression during pregnancy were used as measures of exposures for examining associations with the pregnancy outcomes of preterm birth by gestational age (GA) and birth weight (BW) adjusting for race, age, food stamp eligibility, marital status, previous preterm births, first birth, chorioamnionitis, bacterial vaginosis, and smoking. Interim data from the first 814 deliveries demonstrate that maternal periodontal disease at antepartum and incidence/progression of periodontal disease are significantly associated with a higher prevalence rate of preterm births, BW < 2,500 g, and smaller birth weight for gestational age. For example, among periodontally healthy mothers the unadjusted prevalence of births of GA < 28 weeks was 1.1%. This was higher among mothers with mild periodontal disease (3.5%) and highest among mothers with moderate-severe periodontal disease (11.1%). The adjusted prevalence rates among GA outcomes were significantly different for mothers with mild periodontal disease (n = 566) and moderate-severe disease (n = 45) by pair-wise comparisons to the periodontally healthy reference group (n = 201) at P = 0.017 and P < 0.0001, respectively. A similar pattern was seen for increased prevalence of low birth weight deliveries among mothers with antepartum periodontal disease. For example, there were no births of BW < 1000 g among periodontally healthy mothers, but the adjusted rate was 6.1% and 11.4% for mild and moderate-severe periodontal disease (P = 0.0006 and P < 0.0001), respectively. Periodontal disease incidence/progression during pregnancy was associated with significantly smaller births for gestational age adjusting for race, parity, and baby gender. In summary, the present study, although preliminary in nature, provides evidence that maternal periodontal disease and incident progression are significant contributors to obstetric risk for preterm delivery, low birth weight and low weight for gestational age. These studies underscore the need for further consideration of periodontal disease as a potentially new and modifiable risk for preterm birth and growth restriction.

Adult↗
PubMed2004

Smoking before the birth of a first child is not associated with increased risk of breast cancer: findings from the British Women's Heart and Health Cohort Study and a meta-analysis.

It has been suggested that the period between puberty and first birth is a time when the breast is particularly susceptible to carcinogenic effects. In a cohort of 3047 women aged 60-79 years (N=139 breast cancer cases), we found no association between smoking before the birth of a first child and breast cancer risk: fully adjusted (for age, number of children, age at birth of first child, age at menarche, age at menopausal, hysterectomy and/or oophorectomy, ever use of oral contraception, use of hormone replacement therapy, alcohol consumption, body mass index, childhood and adulthood social class) odds ratio 1.06 (95% confidence interval: 0.72, 1.56). The pooled estimate from a meta-analysis of our study and 11 previously published studies (N=6528 cases) was 1.07 (0.94, 1.22). We conclude that smoking prior to the birth of a first child is not associated with increased risk of breast cancer.

Aged↗
PubMed1976

Histologic specificity of the effect of age at birth of first child on breast cancer risk.

Slides of 531 breast cancers from Glamorgan, Wales, were classified according to the presence or absence of each of three histologic characteristics: stromal infiltration by linear strands of tumor cells, areas of intraductal carcinoma, and areas of lobular carcinoma in situ. The proportion of tumors with each of these characteristics was positively associated with age at first child-birth. Increasing age at first birth had a strong positive effect on the incidence risk of tumors with any of these features, but only a small effect on risk of tumors with none. For parous women, the rate of breast cancer with or without linear strands, with or without areas of intraductal cancer, and without areas of lobular carcinoma in situ was lower than for nulliparous women. Parity appeared not to reduce the risk of tumors with areas of lobular carcinoma in situ.

Adult↗
PubMed1978

Risk factors of breast cancer in Burma.

A hospital-based case-control study of breast cancer was undertaken in Rangoon. The age-standardized incidence rate, 25.1 per 100,000 woman-years and the shape of the age-incidence curve show that Rangoon women have an intermediate level of breast cancer risk compared to women of other countries in the world. The analysis is based on 193 cases and 400 controls. Breast cancer risk was found to be directly related to educational attainment. There was an increased risk associated with early menarche and late menopause. The most striking finding was the strong inverse relationship between risk and parity; women who had six or more children have only one-third the breast cancer risk of married women who had less than four children. This association is not confounded by case-control differences in age at birth of first child. The association of breast cancer risk with age at first birth was not striking; only women with a first birth after age 30 were at increased risk. Breast cancer risk was unrelated to lactation. Overall, the epidemiology of breast cancer in Burma is similar to that in most other countries. However, the possibility of an unusual relationship of risk to parity and age at first parturition warrants further exploration.

Adult↗
PubMed1999

Early childhood nutrition, education and fertility milestones in Guatemala.

Data on fertility milestones were collected in 1994 and linked to information collected in a trial conducted in eastern Guatemala between 1969 and 1977, to examine whether early childhood nutrition was associated with the timing of fertility milestones. In the original trial, two pairs of villages were randomly allocated to receive either a high energy, high protein supplement (Atole) or a low energy, no-protein supplement (Fresco). Mean age at follow-up was 23.47 y (n = 240). About 62% of women had experienced first birth (median age at first birth = 19.83 y). The median intervals from menarche to first intercourse and from first intercourse to first birth were 5.67 and 0.95 y; they were 1.68 and 0.06 y shorter, respectively, for the Atole group than for the Fresco group. Women who had received Atole in utero and/or during early childhood experienced earlier milestones even after adjusting for socioeconomic status (SES), education and age at the prior event. Median age at first birth was 1.17 y earlier for the Atole group. Better growth during early childhood (not severely stunted) led to earlier milestones (median age at first birth was 1.04 y earlier), primarily among women with illiterate fathers. Completion of primary school significantly delayed fertility milestones; the median age at first birth was 4.27 y later for those who completed primary school compared with those who did not (P < 0.05). In sum, improved nutrition during early childhood results in earlier fertility milestones, but the effects of schooling in delaying fertility milestones are greater in magnitude. Intervention programs that improve early childhood nutrition should be accompanied by investments in education that ensure that girls complete primary school.

Adult↗
PubMed1999

Fertility patterns after appendicectomy: historical cohort study.

OBJECTIVE: To examine fertility patterns in women who had their appendix removed in childhood. DESIGN: Historical cohort study with computerised data and fertility data for this cohort and for an age matched cohort of women from the Swedish general population. The cohorts were followed to 1994. SETTING: General population. PARTICIPANTS: 9840 women who were under 15 years when they underwent appendicectomy between 1964 and 1983; 47 590 control women. MAIN OUTCOME MEASURES: Diagnoses at discharge. Distributions of age at birth of first child among women with perforated and non-perforated appendix and women who underwent appendicectomy but were found to have a normal appendix compared with control women by using survival analysis methods. Parity distributions at the latest update of the registry were also examined. RESULTS: Women with a history of perforated appendix had a similar rate of first birth as the control women (adjusted hazard ratio 0.95; 95% confidence interval 0.88 to 1. 04) and had a similar distribution of parity at the end of follow up. Women who had had a normal appendix removed had an increased rate of first births (1.48; 1.42 to 1.54) and on average had their first child at an earlier age and reached a higher parity than control women. CONCLUSION: A history of perforated appendix in childhood does not seem to have long term negative consequences on female fertility. This may have important implications for the management of young women with suspected appendicitis as the liberal attitude to surgical explorations with a subsequently high rate of removal of a normal appendix is often justified by a perceived increased risk of infertility after perforation. Women whose appendix was found to be normal at appendicectomy in childhood seem to belong to a subgroup with a higher fertility than the general population.

Adolescent↗
PubMed1987

Childbearing among young Latino women in the United States.

We analyzed 1979 and 1982 data from the Youth Cohort of the National Longitudinal Surveys (NLS) of Labor Market Experience to compare rates of early childbearing among White, Black, Mexican-origin and Puerto Rican women up to age 21. Latino young women fall in between the extremely low rate of the Whites and the extremely high rate of the Blacks. Mexican and Puerto Rican young women have similar proportions of premarital first births, but the marital first birth rate for young Mexicans is twice that of the Puerto Ricans. The bulk of Mexican first births, like births to Whites, occur within marriage, while Puerto Rican first births are similar to those of Blacks, the majority being out-of-wedlock. These racial/ethnic differences in premarital first birth rates do not change greatly when socioeconomic status, and birthplace of respondents and respondents' parents are controlled.

Adolescent↗