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PubMed1983

Reproductive factors in the aetiology of breast cancer.

An interview study of 1,362 breast cancer cases and 1,250 controls identified through a multi-centre screening project allowed an evaluation of reproductive determinants of breast cancer. Risk increased linearly with age at first livebirth; women with a birth after age 30 showed 4-5-fold excess risks compared to those with a birth prior to 18, while the risk for nulliparous women resembled that for women whose first birth was in their late twenties. The protection conferred by an early first pregnancy prevailed for pregnancies that ended in a livebirth or stillbirth, but not for those that terminated in other outcomes. Among parous women, a first trimester abortion prior to a livebirth was not associated with an elevated risk, except in the event of multiple miscarriages (RR = 2.2, 95% Cl 0.9-5.1). Although numbers were limited, women who reported an induced abortion in the absence of ever having a livebirth showed some elevation in risk. Age at first livebirth explained most associations, but some residual reduction in risk was noted for multiparous women and those with several births at an early age. There was evidence that delays in birth after marriage increased risk, but this did not explain the high risk associated with late age at first birth.

Abortion, Spontaneous↗
PubMed2002

Complexities in ETS-domain transcription factor function and regulation: lessons from the TCF (ternary complex factor) subfamily. The Colworth Medal Lecture.

The ETS-domain transcription factor family can be divided into a series of subfamilies. Elk-1 represents the founding member of the ternary complex factor (TCF) subfamily. By focusing on the TCF subfamily, we can demonstrate the complexities that exist in the function and regulation of ETS-domain transcription factors. This article focuses on Elk-1 in detail and summarizes the functions of other TCFs. The key themes covered include the domain structure of the TCFs, the mechanisms of complex formation with serum response factor, regulation of TCFs by mitogen-activated protein kinase cascades, and transcriptional regulatory properties of the TCFs. Finally, the emerging role of the TCFs in vivo is discussed. A picture is developing indicating that, while these proteins exhibit significant sequence and functional conservation, key differences in their structure and regulation are being identified which may relate to unique functions of these proteins in vivo.

Amino Acid Sequence↗
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↗
PubMed1987

A case-control study on breast cancer risk factors in a southern European population.

A case-control study has been carried out among women attending a screening service in Palermo (Sicily) from 1974 through 1983 to ascertain the distribution of the most frequently investigated risk factors for breast cancer in a southern European population. Information has been obtained from the archives of the screening service. The analysis was separately conducted for pre- and post-menopausal cases and non-cases. Risk factors for pre-menopausal women are: nulliparity (nulliparous versus parous: OR 2.17, 95% CI 1.41-3.32); age at first birth (25-29 versus less than 20: OR 2.16, 95% CI 1.17-4.00); interval between menarche and first birth (greater than 20 years versus less than 6: OR 5.34, 95% CI 2.08-13.66); number of births (greater than 4 versus 1-2: OR 1.98, 95% CI 1.10-3.50). Risk factors for post-menopausal women are: nulliparity (nulliparous versus parous: OR 2.18, 95% CI 1.59-2.99); age at first birth (greater than 29 versus less than 20: OR 1.84, 95% CI 1.13-2.99); interval between menarche and first birth (16-20 years versus less than 6: OR 2.15, 95% CI 1.20-3.85). Age at menarche, age at menopause, breast feeding and family history were not found to be risk factors for breast cancer in the investigated population. The existence of influencing differences between northern and southern populations has been postulated.

Adult↗
PubMed1981

Socioeconomic differentials and trends in the timing of births.

This report contains an analysis of cumulative birth probabilities within first marriages in the United States. Trends and differentials in these probabilities, by race, Hispanic origin, education at first marriage, farm origin, religious preference, and timing of first birth are discussed. The probabilities are shown for specified birth order intervals and age at first marriage or previous birth.

Adolescent↗
PubMed1996

Effects of the level of asphyxia during delivery on viability at birth and early postnatal vitality of newborn pigs.

Newborn pigs (n = 117) were used to provide information on the relationships of degree of asphyxia during delivery, viability at birth, and some striking aspects of postnatal vitality including survival, interval between birth and first udder contact and between birth and first suckling, rectal temperature at 24 h of life (RT24), and growth rate over the first 10 d of life. The degree of asphyxia at birth was estimated from cord blood pCO2, pH, and lactate levels. Onset of respiration, heart rate, skin color, and attempts to stand during the first minute after birth were used to estimate the viability score. Neonatal asphyxia, i.e., decreased blood pH and increased blood pCO2 and lactate, was associated with the production of unusually high levels of catecholamines. The degree of asphyxia increased with late position in the birth order (P < .01) and was higher in piglets born posteriorly (P < 0.5). Further, the average blood pCO2 within a litter increased (P < .05) with litter size. The was an inverse relationship between the degree of asphyxia and the viability score (P < .001). Highly viable piglets reached the udder more rapidly (P < .001) and had a higher RT24 (P < .001) than those of low viability. Plasma glucose concentrations increased with blood pCO2 and plasma epinephrine concentrations (P < .001). Neonatal asphyxia reduced postnatal vitality by delaying the first contact with the udder (P < .03) and was associated with a lower RT24 (P < .05), growth rate (P < .001), and survival over 10 d (P < 0.06). These variables, i.e., interval between birth and first udder contact, RT24, and growth rate, were correlated with birth weight (P < .001); RT24 was also shown to decrease (P < .001) with the time taken to reach the udder. Overall, results suggest that piglet suffering from asphyxia during delivery are less viable at birth and less prone to adapt to extrauterine life.

Animals↗
PubMed1975

Frequency of marriage and live birth among survivors prenatally exposed to the atomic bomb.

Frequency of marriage and birth as of January 1973 was determined for persons exposed in utero to the atomic bombs in 1945 and for controls. The marriage rate was lower in persons heavily exposed in utero than in the non-exposed or lightly exposed. This difference is attributed partly to the lesser marriageability of persons with mental retardation who are significantly more numerous among the heavily exposed, and partly to unmeasured variables, possibly including social discrimination against survivors of the atomic bomb. No consistent relation was observed between radiation exposure and three reproductive indices: childless marriages, number of births, and interval between marriage and first birth.

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↗
PubMed1978

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

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

Adolescent↗
PubMed2001

Pregnancy outcome and birth spacing among Palestinian women between 1940 and 1989.

In a sample of 1,250 Palestinian women living in cities, villages and refugee camps of the West Bank over a period of 50 years, we studied the number of pregnancies, children and miscarriages per woman, the waiting time to the first pregnancy, birth spacing between children, and the average age of women at first live birth. The average number of pregnancies, the percentage of miscarriages, the waiting time to the first pregnancy and the birth interval between children decreased with time in all locations. The average age of women at first live birth in cities and villages showed very little difference, but slightly lower in refugee camps.

Abortion, Spontaneous↗
PubMed2002

Reproduction life history and hip fractures.

PURPOSE: The present study assesses the association between reproduction and hip fractures. METHODS: We used two surveys on elderly Danish twins of both sexes and the Danish National Register of Patients. In a cross-sectional study of 2045 twins aged 75-98 years in 1995, we studied the association between different aspects of reproduction and hip fractures leading to hospitalization between 1977 and 1994. In a prospective study, 3057 twins aged 66-99 years in 1977 were followed for a total of 29,112 years, and the association between number of children and incidence of hip fractures was investigated. RESULTS: In the cross-sectional study, as well as the prospective study, we found, for both sexes, that having no children was associated with a higher risk of hip fracture compared to having at least one child. When excluding persons without children, we found no effect of number of birth events/children. In the cross-sectional study, we found no effect of birth interval length or age at first birth. For women, we found an effect of age at last birth. CONCLUSIONS: No "cost-of-reproduction" in terms of hip fractures was observed. On the contrary, we found that having one or more children was associated with a lower risk of hip fracture.

Aged↗
PubMed1982

Induction of parturition in the pig using a new prostaglandin analogue (K11941).

Eighty seven sows, taken from a herd whose mean gestation length was 116 days, were allotted at random on day 114 of gestation to one of five treatment groups as follows: (1) 175 mug prostaglandin analogue (closprostenol I.C.I. Ltd) (2) 1 mg K11941 (alfaprostol VETEM Ltd), (3) 2 mg K11941, (4) 3 mg K11941 (5) 2 ml saline (control). All prostaglandin analogues induced parturition significantly earlier than controls (P < 0.05), but there were no differences between any of the prostaglandin treatments in the interval to birth of the first piglet (P > 0.05). The mean intervals to parturition were 24.6, 22.3, 24.9, 30.7 and 53.0 hours for treatments 1, 2, 3, 4 and 5 respectively. Almost two-thirds of treated sows farrowed during the working period of the day following injection compared with a small proportion of control animals. Induction of parturition had no effect on birth weight, piglet survival to 3 weeks or on subsequent weaning to service interval in treated sows. Results show that this new analogue of prostaglandin (K11941) is effective in inducing farrowing in the sow.

Journal Article↗
PubMed1983

On a modification of life table technique for analysis of birth interval data and its application.

"This paper presents some modifications [of] the usual life table technique to analyse the data on the time of first birth and inter live birth intervals which are compiled from the birth histories of females, of varying marital durations, enumerated in a retrospective survey." The fact that a female may not be exposed to the risk of conception following childbirth or marriage, because of postpartum amenorrhea or of customs involving visits to parents, is taken into account. A method to obtain maximum likelihood estimates of the conditional risk of conception is given, and an analysis of birth intervals is presented using this technique and data for India from the Rural Development and Population Growth--A Sample Survey 1978.

Amenorrhea↗