Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “First Birth”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources
PubMed1988

Reproductive factors and risk of cervical cancer by cell type. A prospective study.

Relationships between reproductive variables and risk of cervical cancer were examined in a follow-up of 62,079 women in Norway from 1961 through 1980. For the 342 cases classified as squamous cell carcinomas, a higher risk was observed in ever married than in never married women. The risk was especially high among women married more than once and women who were widowed or divorced before start of follow-up. High age at first birth was associated with low risk. The estimated odds ratio for women with first birth at age 35 years or later versus 19 years or earlier was 0.18 (P less than 0.001) in analyses with adjustment for age, urban-rural place of residence and parity. In analyses with adjustment for age at first birth, neither parity or age at first marriage, nor age at menarche or menopause showed significant associations with squamous cell carcinoma. For the 30 cases classified as adenocarcinomas, no significant associations emerged with reproductive factors. The effects of marital status as well as age at first birth differed significantly between adenocarcinomas and squamous cell carcinomas, suggesting dissimilar aetiologies. Although associations between reproductive factors and squamous cell carcinoma may largely be secondary to relationships with sexual habits, there are indications that the association with age at first birth cannot be entirely explained in this way.

Adenocarcinoma↗
PubMed1979

The period between birth and first suckling in dairy calves.

The period between birth and first suckling was recorded for 82 dairy calves. 11 per cent of heifers' calves and 46 per cent of cows' calves had not suckled by 6 h after birth. All calves, whether suckling spontaneously or put to the teat at 6 hr, had adequate 48 h total serum immunoglobulin levels.

Animals↗
PubMed1975

Marital and reproductive experience in a community-wide epidemiological study of breast cancer.

The relationship of marital and reproductive experience to human breast cancer was studied using data collected during 1956-1962 by the Department of Biostatistics and Epidemiology at the Roswell Park Memorial Institute in Buffalo, New York. Information of epidemiological interest was obtained from all women with cancers of the reporductive organs in Buffalo, New York, and the adjoining township of Kenmore. For comparison, a probability sample of the same population was selected. During 1965-1967, an International Collaborative Study with similar objectives found a striking positive relationship between age at first birth and breast cancer risk. This finding can be interpreted as either indicating that an event associated with first birth at an early age protects against the development of breast cancer or that the hormonal status of a women both produces a delay in a woman becoming pregnant and increases the risk of developing breast cancer. The analysis of marital and reproductive histories in the Buffalo population study confirms previous reports of an increasing risk of breast cancer with increasing age at first birth. Attempts to distinguish the two interpretations mentioned by analyzing the interval between first marriage and time of birth in addition to age at first birth were not conclusive. This necessitated a similar analysis of data available in a larger series of 1164 breast cancer patients and 1200 non-neoplastic controls hospitalized at the Roswell Park Memorial Institute during 1957-1965. The results do not show an influence of interval between first marriage and first birth but do show an increased risk of breast cancer with increasing age at first birth. The results are thus consistent with a protective effect of an earyl age at first birth. These findings also have a bearing on recent suggestions that ovulatory failure predisposes to development of breast cancer.

Adult↗
PubMed2005

Mode of delivery and problems in subsequent births: a register-based study from Finland.

OBJECTIVE: The purpose of this study was to investigate the effects of delivery on problems in subsequent births. STUDY DESIGN: This was a cohort study that used register data for 73,104 mothers who had their first birth from 1987 to 1989 and subsequent births from 1987 to1998. Three analyses were performed: (1) examination of second births by mode of delivery in the first birth, with adjustment for confounders, (2) same parameter, with exclusion of women with persistent problems, and (3) examination of third births for women with a first birth vaginal delivery. RESULTS: More complications and poorer infant outcome were found at later births when the first or second birth was by cesarean delivery than after a first spontaneous vaginal delivery, even when women with persistent problems were excluded. Women with instrument first births had a similar rate of complications in the second birth to women with spontaneous vaginal births, but some infant outcomes were poorer. CONCLUSION: Problems that are subsequent to cesarean delivery are unlikely to be explained entirely by indications for cesarean delivery.

Cesarean Section↗
PubMed1995

Reproductive factors and the risk of renal cell cancer among women.

In etiologic studies of renal cell carcinoma the role of reproductive variables and the use of exogenous hormones have not been well examined. In a population-based case-control study including 165 female cases and 227 controls, we assessed the risk of renal cell cancer associated with reproductive factors and use of oral contraceptives and menopausal hormones. Odds ratios were computed using logistic regression analyses. Risk was positively associated with number of births and inversely associated with age at first birth, with the largest increases in risk (more than 2-fold) among women with 5 or more births after age 25. After adjustment for age, smoking status, body mass index and age at first birth, women with 5 or more births had a 2-fold risk (OR = 2.2, 95% CI = 1.2-4.0) relative to those with 1 or 2 births. Age at first birth, however, was no longer a risk factor when the number of births was adjusted for. The association with parity was considerably stronger among women with a history of hypertension or above-median body mass index than among those without these conditions. In addition, risk was reduced among long-term oral contraceptive users but elevated among women who had had a hysterectomy or used menopausal hormones. Our findings suggest that reproductive factors, particularly the number of births, may play an etiologic role in renal cell cancer among women and deserve further study.

Adult↗
PubMed2004

Unintended pregnancy among newly married couples in Shanghai.

CONTEXT: Though contraceptive failure and induced abortion in China have both attracted research attention, the somewhat broader topic of unintended pregnancy has been neglected. METHODS: A total of 7,872 newly married couples, enrolled between 1987 and 1988, were followed up until 1994-1995; only 2% were lost to follow-up. During face-to-face interviews, background and fertility-related data were collected. Chi-square tests and logistic regression were used to assess associations with unintended pregnancy. RESULTS: By three months after marriage, 461 couples had conceived; 57% of nonpregnant wives said that their preferred interval between marriage and conception was no more than three months. Twenty-one percent of pregnancies occurring between marriage and first birth were reported as unintended; 81% of these resulted from contraceptive failure. The majority of unintended pregnancies were carried to term; 13% were aborted. The younger the wife and the greater her desired interval between marriage and conception, the greater the likelihood that a pregnancy occurring before first birth was unintended. After first birth, 43% of couples experienced one or more unintended pregnancies, 98% of which were aborted in accordance with the one-child policy. The majority of these pregnancies occurred in the 12 months after first birth, when couples tend to rely on ineffective methods of contraception. The odds of having an unintended pregnancy after first birth were slightly elevated if at least one spouse desired a second child. CONCLUSIONS: Unintended pregnancies are common among married couples in Shanghai. Policies to reduce unintended pregnancies, and abortions, should focus particularly on postpartum contraception.

Adult↗
PubMed1992

Risk factors for cervical intraepithelial neoplasia.

To evaluate risk factors for cervical intraepithelial neoplasia (CIN), data were collected in a case-control study based on 366 patients (58 with CIN class 1, 70 with CIN class 2, and 238 with CIN class 3) and 323 control subjects with normal cervical smears interviewed on selected days at the same screening clinics where cases had been identified. No relationship emerged between indicators of socioeconomic status (education and social class) and risk of mild/moderate (considered together) and severe dysplasia. A total of 55 (43%) patients with CIN class 1 or 2, 107 (45%) patients with CIN class 3, and 94 (29%) controls were current smokers. The corresponding relative risk (RR) estimates for current versus never smokers were 1.9 (95% confidence interval [CI] 1.2 to 3.0) for patients with CIN class 1 or 2 and 2.5 (95% CI 1.7 to 3.6) for patients with CIN class 3, and the risk increased with the number of cigarettes smoked per day. No relationship was observed between oral contraceptive use, parity, spontaneous or induced abortions and the risk of CIN, but patients tended to report earlier age at first birth than control subjects. Compared with women reporting their first birth before the age of 20 years, the risk estimates were 0.5 and 0.4, respectively, for patients with CIN 1 or 2 and patients with CIN 3 in women reporting first birth at 20 to 24 years of age. The risk estimates were 0.5 and 0.6 for those reporting their first birth at age 25 or later, but the trends in risk were not statistically significant. The number of sexual partners was directly associated with the risk for both histopathologic subgroups. Compared with women reporting no intercourse or their first intercourse after 22 years of age, women with first intercourse before the age 18 had a RR estimate of CIN class 1 or 2 of 2.3 and of CIN class 3 of 2.4, with the trends in risk being statistically significant. This study confirms considerable similarities in the epidemiology of mild/moderate and severe cervical dysplasia. In addition, it suggests consistency between the epidemiology of intraepithelial and invasive cervical neoplasia for risk factors that are likely to act on one of the first stages of the process of carcinogenesis (i.e., indications of sexual habits) but differences for hormone-mediated factors (i.e., reproductive variables or oral contraceptives).

Abortion, Spontaneous↗
PubMed1995

Menstrual and reproductive factors and pancreatic cancer risk in women.

To investigate possible correlates of the systematically higher pancreatic cancer rates in males than in females, the role of menstrual, reproductive and hormonal factors in females have been assessed using data from a case-control study conducted in Northern Italy. Cases were 133 women with histologically confirmed incident cancer of the pancreas, and controls were 377 women in hospital for acute, non-neoplastic, non-digestive-tract disorders. After allowance for age, education, area of residence and smoking habit, an increased risk of pancreatic cancer was observed in women with early menarche (< or = 13 years) (OR = 1.9; 95% CI: 1.0-3.6), but no significant association was observed with age at menopause or length of fertile life. Parous women were at reduced risk as compared to nulliparous women (OR = 0.7), although the trend in risk with number of births was not significant. No association with spontaneous or induced abortions was observed. Pancreatic cancer risk was inversely related to early age at first birth (first birth < 25 versus nulliparae: OR = 0.5; 95% CI: 0.3-0.9; p-value for trend < 0.01) and to age at last birth (last birth < 25 versus nulliparae: OR = 0.3; 95% CI: 0.1-0.8; p-value for trend < 0.05). Ever-users of estrogen replacement therapy showed a non-significantly increased risk (OR = 2.2). Although no clear pattern of association is evident, the present results are in agreement with previous epidemiological observations and experimental research indicating that hormonal (menstrual and reproductive) factors could explain part of the male-to-female differential in incidence and mortality from pancreatic cancer.

Adult↗
PubMed2000

Diverging fertility among U.S. women who delay childbearing past age 30.

In this paper I examine the evolving association between educational attainment and the timing of births. In the late 1970s, women with four-year college degrees had lower first birth rates before age 30 than women with less education, but rates of first births were similar for the two groups after age 30. From the 1970s to the 1990s, first birth rates decreased before age 30 for all women, but increased after age 30 only for women with four-year college degrees. Parity 2 birth rates also increased for college graduates with a first birth after age 30. These results document widening educational differences in fertility timing between 1975 and 1995, which may reflect period changes at later ages in women's work and family lives.

Adolescent↗
PubMed1983

Risk factors for breast cancer.

Since 1976, data were collected to evaluate risk factors for breast cancer in a hospital-based case-control study of 1185 women with breast cancer and 3227 controls. The risk of breast cancer increased with increasing age at first birth; this effect was not accounted for by parity. An early age at first birth appeared to reduce the risk relative to no pregnancy, whereas a late age at first birth was associated with a higher risk than not having a full-term pregnancy. High parity was associated with a reduction in the risk that was independent of that of age at first birth: for parity greater than or equal to 5, compared with parity 1-2, the relative risk estimate was 0.7 (95% confidence interval, 0.5-1.0). Late age at menarche was associated with a lower risk among premenopausal women but not among postmenopausal women. The relative risk decreased with increasing obesity among premenopausal women. Among postmenopausal women, the risk was higher among those who were obese, but there was no evidence of a trend with increasing body mass index. Risk did not vary materially according to history of abortion when gravidity was controlled. Risk was lower among postmenopausal women than among premenopausal women of the same age and increased with increasing age at menopause; bilateral oophorectomy reduced the risk more than hysterectomy alone. A positive history of benign breast disease, a positive family history of breast cancer, Jewish religion, and 12 or more years of education were each independently associated with an increased risk of breast cancer.

Adult↗
PubMed2004

Reproductive factors and extreme levels of maternal serum alpha-fetoprotein: a population-based study.

BACKGROUND: Levels of maternal alpha-fetoprotein (AFP) are increased during multiple gestations and preeclampsia but little is known regarding AFP levels in relation to other reproductive factors. Consequently, the objective of this work was to describe the possible relationship between AFP levels during pregnancy and maternal age at birth, maternal age at first birth, parity, time since previous birth and gender of the offspring. METHODS: Based on national registries we obtained the reproductive history on a population-based cohort of 44 227 women who had serum AFP levels determined in gestational weeks 14-21 and whose present and previous pregnancies resulted in live-born singletons. RESULTS: Many previous births and an interval of less than 2 years since last birth were significantly associated with extremely low levels of AFP in the mother. However, age at first birth and age at present pregnancy did not influence the AFP level. Women who gave birth to a girl had AFP levels that were 5%[95% confidence interval (CI) 4-6%] lower than those of women who had a boy. Adjustment for birthweight did not significantly affect the estimate. CONCLUSIONS: Low serum AFP levels in pregnancy are significantly correlated with high parity and with a short interval between births. The significantly lower levels of AFP in women who gave birth to girls could indicate a possible gender-specific regulatory mechanism.

Adolescent↗
PubMed1995

Breast cancer in Swedish women before age 50: evidence of a dual effect of completed pregnancy.

We set out to detect a transient increase in risk of breast cancer following childbirth, the existence of which has been postulated, but for which empirical evidence is contradictory. Breast cancers and births occurring among the cohort of Swedish women born after 1939 were linked, yielding 3,439 cases and 25,140 age-matched controls with at least two children. Within three years of their last childbirth, women had an estimated rate of breast cancer of 1.21 (95 percent confidence interval [CI] = 1.02-1.44) times that of women whose last birth was 10 or more years earlier, after adjustment for parity and age at first birth. Further analyses suggested that this effect reflected, in part, a small transient increase in breast cancer risk that lasts for about three years following completed pregnancy. The effect of age at first birth on breast cancer risk appears to be confounded by time since last birth; the parity-adjusted rate ratio for having a first birth at age 35 years or more compared with under 20 years is reduced from 1.72 (CI = 1.14-2.58) to 1.36 (CI = 0.88-2.09) on additional adjustment for time since last birth. A transient increase in breast cancer risk after childbirth appears thus appears to account for part of the effect of age at first birth on breast cancer risk.

Adult↗
PubMed2001

Grand multiparity and the risk of breast cancer: population-based study in Finland.

OBJECTIVES: The significance of reproductive factors on breast cancer risk has so far been characterized in populations with 5-paras as the highest category of parity. We extended these studies to a nationwide cohort of women with at least five births (grand multiparas = GM) by assessing the significance of parity, age at first birth, and average birth interval to the risk of breast cancer. METHODS: The study cohort obtained from the Population Register of Finland comprised 86,978 GM-women; the incidence of cancer cases was obtained from the populated-based Finnish Cancer Registry. During a follow-up of about 2 million person-years, 1508 breast cancers were obtained. Standardized incidence ratios (SIRs) were calculated by dividing the number of observed cases by the number expected on the basis of national rates. RESULTS: In the GM cohort the incidence of breast cancer was low (SIR 0.55, 95% confidence interval 0.52-0.58). The relative risk decreased significantly from 5-paras (SIR 0.60, adjusted for the other study variables) to 8-paras (SIR 0.40). The increase in the age at first birth from less than 20 years to 30+ years nearly doubled the risk (SIR from 0.40 to 0.73). Parity was a significant risk determinant only in ductal cancer, while shortening the birth interval was protective only in lobular cancer. The incidence of advanced breast cancer among GM-women exceeded the population rate in premenopausal women and in women with first birth at the age of 30 years or more. CONCLUSIONS: Our study demonstrated that young age at first birth and increasing number of births were independent and powerful protective factors from the fifth child onwards, while birth interval was weak in this respect. The tumor morphology and the clinical advancement of malignancy modified the dependence of breast cancer risk on reproductive variables.

Aged↗
PubMed1995

Abortion and breast cancer risk in seven countries.

Epidemiologic studies have been inconsistent in suggesting an association between abortion and breast cancer risk. Whether the protection provided by a full-term pregnancy also results from a short-term pregnancy or whether a prematurely terminated pregnancy could increase the risk of breast cancer is unclear. Data from a large, international collaborative study were used to evaluate the association between abortions, whether spontaneous or induced, and breast cancer risk. The data from seven countries included 3,958 breast cancer cases and 11,538 hospital controls with information on abortion history obtained through interviews. Compared with nulliparous women with no abortion (baseline), the odds ratios (OR) and 95 percent confidence intervals (CI) were: for nulliparous women with a history of prior abortion, 0.86 (CI = 0.68-1.08); for parous women with no history of abortion, 0.63 (CI = 0.57-0.69); for parous women with abortion before first birth, 0.82 (CI = 0.69-0.97); and, for parous women with abortion only after first birth, 0.70 (CI = 0.63-0.79). When restricting analysis to parous women, those with a history of abortion exhibited an elevated OR suggesting a 29 percent risk increase if the incomplete pregnancy occurred before first birth (CI = 1.16-1.36) and an 11 percent risk increase for abortion only after first birth (CI = 1.02-1.20) compared with women without such history. The associations observed were stronger among the youngest women. These results do not support a large overall association between abortion and breast cancer risk.

Abortion, Induced↗
PubMed1996

Reproductive variables and risk of uterine cervical cancer in Norwegian registry data.

The influence of reproductive variables on cervical cancer incidence, controlling for other sociodemographic factors, was estimated in Norwegian register and census data, using Poisson regression models. Among the 1.3 million women under observation, a total of 2,870 cases of cervical cancer were diagnosed. According to models restricted to parous women, parity level had no independent impact on cervical cancer incidence, but a clear effect of age at first birth was noted. It was most pronounced in the squamous cell carcinomas, where the incidence was reduced by 48 percent from age at first birth < 21 years to age at first birth 27+ years. Women without children had the same cervical cancer incidence as parous women with a first birth after age 24. The sociodemographic variables controlled for exerted a strong net effect on the cervical cancer incidence. Educational level was related inversely to the cancer risk. Moreover, an increased risk was seen for women who had given birth when they were still single (never married) and for those who were divorced/separated at the time of the last previous census. A fairly small excess risk was found to be associated with living in non-rural compared with rural areas.

Adult↗
PubMed2004

Premature death among teenage mothers.

OBJECTIVE: Some data suggest an association between teenage childbearing and premature death. Whether this possible increase in risk is associated with social circumstances before or after childbirth is not known. We studied premature death in relation to age at first birth, social background and social situation after first birth. DESIGN: Population-based cohort study. SETTING: Women born in Sweden registered in the 1985 Swedish Population Census. POPULATION: Swedish women born 1950-1964 who had their first infant before the age of 30 years (N= 460,434). METHODS: Information on the women's social background and social situation after first birth was obtained from Population Censuses. The women were followed up with regard to cause of death from December 1, 1990 to December 31, 1995. Mortality rate ratios and 95% confidence intervals (CI) were calculated. MAIN OUTCOME MEASURES: Mortality rates by cause of death. RESULTS: Independent of socio-economic background, teenage mothers faced an increased risk of premature death later in life compared with older mothers (rate ratio 1.6, 95% CI 1.4-1.9). The increased risk was most evident for deaths from cervical cancer, lung cancer, ischaemic heart disease, suicide, inflicted violence and alcohol-related diseases. Some, but not all, of these increases in risk were associated with the poorer social position of teenagers mothers. CONCLUSIONS: Teenage mothers, independent of socio-economic background, face an increased risk of premature death. Strategies to reduce teenage childbearing are likely to contribute to improved maternal and infant health.

Adolescent↗
PubMed1995

Effects of menstrual and reproductive factors on the risk of breast cancer: meta-analysis of the case-control studies in Japan.

To elucidate the magnitude of the effect of menstrual and reproductive factors on breast cancer occurrence among Japanese women, we reviewed eight case-control studies previously conducted in Japan and used a quantitative method (meta-analysis) to summarize the data. While individual studies have different methods and populations, the estimated odds ratios (ORs) in the studies were statistically homogeneous for all study variables. It was confirmed that early age at menarche, late age at first birth, and premenopausal status are significantly associated with risk of breast cancer; an estimated combined OR of 0.68 (95% confidence interval (CI): 0.59-0.77) was obtained for women with onset of menstruation after age 16 compared to those before age 14. Nulliparous women had higher risk than women with first birth before age 25 (OR = 1.56 95%, CI: 1.27-1.91). The OR for women with first birth after age 35 was 2.26 (95% CI: 1.85-2.77) compared to women at first birth before age 25. Premenopausal women had a higher risk than women with menopause before age 50 (OR = 2.21, 95% CI: 1.53-3.20). We also found a significant protective effect of high parity after controlling for age at first birth and the other menstrual factors. The OR estimate for 3 or more births compared to nulliparity was 0.68 (95% CI: 0.54-0.86). The meta-analysis provided quantitative estimates of breast cancer risk among Japanese women with improved precision.

Age Factors↗
PubMed1998

International variability in ages at menarche, first livebirth, and menopause. World Health Organization Collaborative Study of Neoplasia and Steroid Contraceptives.

The occurrences and timing of reproduction-related events, such as menarche, first birth, and menopause, play major roles in a woman's life. There is a lack of comparative information on the overall patterns of the ages at and the timing between these events among different populations of the world. This study describes the variability in reproductive factors across populations in Europe, the Americas, Asia, Australia, and Africa. The study sample consisted of 18,997 women from 13 centers in 11 countries interviewed between 1979 and 1988 who comprised the control group in a World Health Organization international, multicenter case-control study of female cancers. All were surveyed with the same questionnaire and methodology. Overall, a typical woman in this study reached menarche at age 14 years and delivered her first live child 8 years later, at age 22. She was 50 years old at natural menopause and had had 36 years of reproductive life. The median ages at menarche varied across centers from 13 to 16 years. For all centers, the median age at first livebirth was 20 or more years, with the largest observed median (25 years) occurring in China. The median delay from menarche to first livebirth ranged from 5 to 11 years. Among the centers, the median age at natural menopause ranged between 49 and 52 years. In most populations, younger women had a first birth at a later age than did older women. This tendency was more accentuated in some populations. These results reveal, perhaps for the first time, the variability of reproductive histories across different populations in a large variety of geographic and cultural settings. Except for menopause, international variability is substantial for both biologically related variables (age at menarche) and culturally related variables (age at first birth). There is a generational effect, characterized by more variability of age at first birth and delay to first birth in the younger than in the older generations.

Adolescent↗