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PubMed2003

Women empowerment and marital fertility in Oman.

International studies have the inverse relationship of women education and empowerment on fertility. Our aim is to study the association of women education and empowerment with some of fertility indicators or determinants namely; total number of children ever-born, age of women at her first birth and the last closed birth interval length in a community based survey (National Health Survey, 2000) A cross-sectional survey of the health status of Omani community was designed. Face to face interview to 2037 ever married women including demographic data, fertility patterns, family planning, two women empowerment indices (decision making and freedom of movement), and other reproductive health modules. About 31% of the sample was considered highly empowered in decision- making and the mean number of decisions taken in the household was 4.46 for the overall sample. For freedom of movement, 29% of the sample was highly empowered with a mean number of 3.88 for the overall sample. The mean values of both indices varied significantly according to age, residence, level of education and work status. Higher freedom of movement score women was more likely to have less number of children in the first 20 years of marriage. Women of 'higher score of decision making index were more likely to have longer closed birth interval. Those scored low in the decision making index were more likely to get a child at an earlier age. In developing countries where fertility limitation depend on "modern" methods, women's education and autonomy are considered as strong tools to make changes in demographic transition.

Adolescent↗
PubMed2004

Reproductive output, maternal age, and survivorship in captive common marmoset females (Callithrix jacchus).

Common marmosets (Callithrix jacchus) demonstrate significant variation in reproductive output on both a yearly and lifetime basis in comparison to other anthropoid primates. We explore the factors that may be most important in determining reproductive variation in captive common marmosets. Studies have found that maternal age, maternal condition, and dam survivorship are related to reproductive output; however, these reports are not in agreement and are far from conclusive. With the use of a large, multicolony, demographic database pooling data across five marmoset colonies, we examined litter information for 1,649 litters, and reproductive summaries for 400 dams to assess 1) how reproductive output variation (total production, total weaned production) is determined by litter size, interbirth interval (IBI), age at first birth, and dam survival age; 2) the relationship between maternal age and reproductive output variables; and 3) relationship between the reproductive output variables and survival. We used stepwise regression procedures to describe the amount of variation in lifetime reproductive output among dams, and found that mean litter size accounted for 18% of the variance in total production, survival age accounted for 10.6%, age at first birth accounted for 8.8%, and mean IBI accounted for 5%. For total (nonzero) weaned production, survival age accounted for 7.6% of variance, age at first birth accounted for 7.2%, mean IBI accounted for 2%, and mean litter size accounted for 1.6%. We identified significant effects (P<0.05) of maternal age on litter size and IBI length, but no effect of dam age on weaned litter size. Cox proportional hazards regression analyses revealed significant effects (P<0.01) of number of litters, age at first birth, and site on dam survivorship. Dams that produced more litters showed higher survivorship. Age at first birth showed a positive relationship with dam survivorship, i.e., dams that delayed first reproduction had higher survival. Our findings about reproductive variation in marmosets may have practical applications for the management of marmoset breeding colonies.

Animals↗
PubMedDate not supplied

Menarcheal age and subsequent patterns of family formation.

We examine whether age at menarche affects age at first marriage or first birth using two samples of U.S. women. Data are drawn from the Tremin Trust, a longitudinal study of menstrual cycles that recruited white women who were students at the University of Minnesota and from a survey of a nationally representative sample of white women born between 1900 and 1910. Regression models with cubic splines were used to analyze the relationship between age at menarche and age at first marriage. Cox proportional hazard models were used to examine the effect of age at menarche on the interval between marriage and first birth. Unlike earlier work, we found that once secular trends in both age at marriage and age at menarche were taken into account, there was no evidence that age at menarche affects either age at marriage or the timing of first births in these U.S. women.

Adolescent↗
PubMedDate not supplied

[The importance of time intervals between childbirth and anemia in pregnancy].

UNLABELLED: During pregnancy some parameters have been studied in order to detect anaemia: amount of erythrocytes, haematocrits, haemoglobin and iron in the serum of 100 women-secundiparae. The greater group of pregnant women (68%) decided for the second pregnancy after two years, while the smaller group (32%) after four years at least. All parameters related to anaemia were present in the groups of shorter time intervals between births. Thus, in the first trimester anaemia was detected in 13.3% of pregnant patients, while only 7.1% in those with a longer interval between deliveries. In the second trimester 33.3% of pregnant women with shorter time intervals suffered from anaemia, and 14.3% of those with a longer interval. The difference is also significant in the third trimester. Namely, 50% of pregnant patients with a shorter interval were anaemic, in comparison to 21.4% of women with a longer interval between deliveries. INTRODUCTION: Anaemia is one of the most frequent illnesses in pregnant patients. The authors found different percentages of its presence in the range from 21 to 80 percent. Sideropenic anaemia is the most common in pregnancy. As Iron is being consumed and lost during delivery, it takes time for its restitution. Therefore Dazabarova advises another childbirth after three years. PURPOSE: Pregnancy and delivery exhaust the organism. It takes time for the recovery and a new pregnancy. Therefore, the purpose of this paper was to examine in what way the time-interval may affect anaemia. METHOD: This paper covers 100 randomized secondiparae. Laboratory examinations were carried out three times during pregnancy, in each trimester separately. The results are shown on the graph so that the difference and importance of the time-interval between deliveries regarding anaemia in pregnant patients, can be noticed. RESULTS: Pregnant women with a two-year interval between deliveries showed anaemia to a greater extent during pregnancy (Graph 1). This was confirmed by tests and was statistically significant (chi 2 = 14.275 and p < 0.001). In women with an interval of four years between deliveries, changes in number of erythrocytes were not statistically significant (chi 2 = 1.167 and p > 0.05). Thus, the difference among the analyzed groups was significant in all trimesters of pregnancy. The results of haematocrits are presented in Graph 2. The difference between the results of greater presence of anaemia in women with shorter time-interval between pregnancies may be statistically significant in the first and second trimesters. In the third trimester, however, the difference still existed, although it was not statistically significant. The results of haemoglobin indicating anaemia (Graph 3) were found in a greater number as pregnancy progressed in women with shorter time-interval between deliveries. This was statistically significant (chi 2 = 15.600 and p < 0.001). In women with greater time-interval between deliveries, a slight increase in haemoglobin was detected, indicating anaemia (chi 2 = 5.918 and p < 0.05). Iron concentrations in the serum indicating anaemia (Graph 4) were constantly decreasing during pregnancy (chi 2 = 7.251 and p < 0.01) in patients with shorter intervals between deliveries, whereas in women with greater time-intervals no significant changes were found (chi 2 = 1.838 and p > 0.05). In Graph 5 the prevalence of anaemia is presented according to the examined parameters. Anaemia was greater in a far larger number of women with shorter intervals between deliveries. This difference is at the limit of statistical significance in the first trimester, tending to become statistically highly significant in the second and third trimesters. DISCUSSION: Frequent pregnancies are one of the causes of anaemia. Namely, they are more often detected in multiparae with shorter time-intervals between deliveries. Our study has confirmed that pregnancy causes haemotopoietic changes (ABSTRACT TRUNCATED).

Anemia↗
PubMedDate not supplied

[Rett syndrome and autism. Early comparative evaluation for signs of autism using family movies].

Rett's syndrome progresses in 4 stages: the first signs of the disorder appear after a period of 6 to 7 months, during which development is considered to be normal. This asymptomatic period is apparently an essential criterion of the diagnosis, but some parents have reported some prodromes. In stage II of the disease (before 3 years), signs common with autism dominate the clinical picture and the diagnosis of the latter was often formulated. Our working hypothesis is that the pedopsychiatric analysis of home movies of young girls with Rett's syndrome, taken by the parents before the age of 2, may be able to show early clinical signs. The present study involved examining home movies of children subsequently diagnosed as having Rett's syndrome (n = 9) in comparison to those of autistic (n = 9) and normal (n = 9) children, using semiological evaluation tools (IBSE, BFE). The persons scoring were not advised of the diagnosis. The observations were thus situated before the disorders and/or at the time of their appearance. The study confirms the asymptomatic interval between birth and the first signs of the disease, it defines the mode of onset and shows the disturbance of certain functions such as intent and imitation, more pronounced in Rett's syndrome children between 12 and 18 months. At this age, it also enables Rett's and autistic children to be differentiated on the basis of the different involvement of the "cognition" function and unusual posture, more pronounced in these girls. It does not, however, differentiate Rett's from autism between 6 and 12 months and it is thus not surprising that at this stage the diagnosis of rett's syndrome or autism may be a source of confusion.

Adolescent↗
PubMed2004

Effects of nurse home-visiting on maternal life course and child development: age 6 follow-up results of a randomized trial.

OBJECTIVE: To test, with an urban, primarily black sample, the effects of prenatal and infancy home visits by nurses on mothers' fertility and economic self-sufficiency and the academic and behavioral adjustment of their children as the children finished kindergarten, near their sixth birthday. METHODS: We conducted a randomized, controlled trial of a program of prenatal and infancy home-visiting in a public system of obstetric and pediatric care in Memphis, Tennessee. A total of 743 primarily black women at <29 weeks of gestation, with no previous live births and with > or =2 sociodemographic risk characteristics (unmarried, <12 years of education, or unemployed), were randomly assigned to receive nurse home visits or comparison services. Outcomes consisted of women's number and timing of subsequent pregnancies, months of employment, use of welfare, food stamps, and Medicaid, educational achievement, behavioral problems attributable to the use of substances, rates of marriage and cohabitation, and duration of relationships with partners and their children's behavior problems, responses to story stems, intellectual functioning, receptive language, and academic achievement. RESULTS: In contrast to counterparts assigned to the comparison group, women visited by nurses had fewer subsequent pregnancies and births (1.16 vs 1.38 pregnancies and 1.08 vs 1.28 births, respectively), longer intervals between births of the first and second children (34.28 vs 30.23 months), longer relationships with current partners (54.36 vs 45.00 months), and, since the previous follow-up evaluation at 4.5 years, fewer months of using welfare (7.21 vs 8.96 months) and food stamps (9.67 vs 11.50 months). Nurse-visited children were more likely to have been enrolled in formal out-of-home care between 2 and 4.5 years of age (82.0% vs 74.9%). Children visited by nurses demonstrated higher intellectual functioning and receptive vocabulary scores (scores of 92.34 vs 90.24 and 84.32 vs 82.13, respectively) and fewer behavior problems in the borderline or clinical range (1.8% vs 5.4%). Nurse-visited children born to mothers with low levels of psychologic resources had higher arithmetic achievement test scores (score of 88.61 vs 85.42) and expressed less aggression (score of 98.58 vs 101.10) and incoherence (score of 20.90 vs 29.84) in response to story stems. There were no statistically significant program effects on women's education, duration of employment, rates of marriage, being in a partnered relationship, living with the father of the child, or domestic violence, current partner's educational level, or behavioral problems attributable to the use of alcohol or drugs. CONCLUSION: This program of prenatal and infancy home-visiting by nurses continued to improve the lives of women and children at child age 6 years, 4 years after the program ended.

Adolescent↗
PubMed1987

Induction of parturition in swine and epostane, a competitive inhibitor of 3 beta-hydroxysteroid dehydrogenase.

The ability of epostane, a competitive inhibitor of the 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) enzyme system, to decrease the peripheral levels of progesterone and induce sows to farrow was examined. Twenty-five sows were randomly divided into five groups. On d 109 of pregnancy, each sow received one of the following treatments: no epostane (Group C); one oral dose of 5 mg (Group O5) or 10 mg (Group O10) of epostane/kg of body weight; or a sc injection of 1 mg (Group I1) or 5 mg (Group I5) of epostane/kg of body weight. During the 24 h after treatment with epostane, the levels of progesterone were approximately one-half of pre-treatment levels. Progesterone was influenced (P less than .01) by treatments and time. The treatment X time interaction (P less than .05) appeared to be due mostly to the difference in response between the sows that received epostane or vehicle. Similar results were observed for estrogen. The interval from treatment to the birth of the first piglet for Groups C, O5, O10, I1 and I5 was 112, 31, 33, 77 and 32 h, respectively, and the intervals differed (P less than .01). Three gifts in Group I1, with an interval of 53, 124 and 133 h, were not considered to have been induced. The route of administration of epostane or dose did not influence (P greater than .05) the interval to the onset of farrowing. The interval from the birth of the first to the last piglet in a litter, the proportion of piglets born live and weaned, and the birth and weaning weights for the five groups were similar (P greater than .05). These results suggest that inhibitors of the 3 beta-HSD can be used to induce farrowing without adversely affecting either the sow or its litter.

3-Hydroxysteroid Dehydrogenases↗
PubMed2005

A fatal attack on an unweaned infant by a non-resident male in a free-ranging group of Japanese macaques (Macaca fuscata) at Katsuyama.

A non-resident male attacked a 4-month-old unweaned infant in a free-ranging group of Japanese macaques (Macaca fuscata) and it died 2 days later from a severe wound. When the infant was alone at the feeding site, the non-resident male rushed at it. The infant ran away as soon as it became aware of the male, but was captured. The male bit the infant on its hand, foot, and arm, while continuously scanning his surroundings. He did not kill the infant immediately and, after the infant escaped, he did not chase or attack it at all. Although the infant's right arm was bleeding heavily, it survived until the following day. The infanticide occurred a few weeks before the mating season began, so the victim's mother soon resumed estrus and the subsequent inter-birth interval was shortened. The first-, second-, and fourth-ranking adult males had died or disappeared a few months before this infanticide, and there were no other group members near the infant when the infanticidal male appeared. The infanticidal male had not been observed before this incident. Compared to one-male groups, the occurrence of infanticide in multi-male groups of Japanese macaques is extremely infrequent. However, in other reports of infanticide in Japanese macaques as well as in this case, it has been noted that infanticide is likely to occur in the pre- or early-mating season, when there are no resident males to defend the infant against attacks, and when a threatening male is least likely to be the infant's father.

Aggression↗
PubMed1999

Long-term pattern of HIV-1 RNA load in perinatally infected children.

The objective of this study was to describe the natural history of HIV-1 RNA load in vertically HIV-1-infected children. HIV-1 RNA in 156 plasma or serum samples (1-14, median 4 from each child) from 32 vertically HIV-1-infected children was detected with the NASBA technique (Organon Teknika, The Netherlands). Twenty-one children were prospectively followed from birth, and 11 were identified and included at the age of 7-89 (median 61) months. The highest numbers of HIV-1 RNA copies were seen at 1.5-3 months of age. A quadratic curve model showed a reduction of HIV-1 RNA with increasing age up to approximately 8 years, and thereafter increasing numbers, p(age) = 0.002, p(age2) = 0.008. This pattern was not typical for individual children in whom a great variation in HIV-1 RNA numbers was seen over time. The interval from birth to the first HIV-1 RNA peak ranged from 1.5 months to more than 2 years. The HIV-1 RNA levels remained relatively high and fluctuating over the years in symptomatic as well as in long-term asymptomatic children. This makes HIV-1 RNA determination in children more difficult to use than in adults, as the only tool for prediction of disease progression and for initiation of therapy.

CD4 Lymphocyte Count↗
PubMedDate not supplied

Population growth and fertility patterns in an Old Order Amish settlement.

BACKGROUND: Since they are a healthy and well-nourished isolate with strong religious proscriptions against birth control, the fertility patterns of the Old Order Amish have long been studied by demographers, particularly those with an interest in natural fertility. AIM: The present report describes population growth, population structure, and fertility patterns in a little-studied Amish settlement located in northeastern Ohio, USA (Geauga Settlement). SUBJECTS AND METHODS: A directory prepared by the Geauga Settlement provides data on the dates of birth of the mother, father, and all children for 1337 families for the period up to 1 January 1993. This information was used to assess population size, population structure, fertility rates, age at marriage, age of mothers at first and last birth, and birth intervals. Estimates of total settlement size were also derived from an older directory covering the period up to 1 January 1988 and a recently published directory which covers the period up to 1 January 1998. RESULTS: The settlement consisted of 7546 individuals in 1988, 8345 individuals in 1993, and 9572 individuals in 1998. The completed marital fertility rate was 7.7 (SD 3.6) births per woman. Total fertility rate decreased by about one birth between 1909 and 1967, in association with a change in fertility patterns, with women born in more recent cohorts tending to have more of their offspring at an earlier age, both of which suggest the existence of behaviours to control fertility. On the other hand, the age at the birth of the last child remained fairly constant over this time period. CONCLUSIONS: There is some suggestion of fertility control by Amish families. However, this control appears to be independent of parity, suggesting that there is no intention to limit family size. It is therefore reasonable to conclude that the Amish in the Geauga Settlement are a natural fertility population.

Adult↗
PubMed1996

Seasonal variation in the time to pregnancy: avoiding bias by using the date of onset.

To study seasonality in human fecundability, measured indirectly by time to the first pregnancy, we used data from 18,970 French-Canadian women who married for the first time during the 17th or 18th century. The time to pregnancy was approximated by the interval between marriage and first birth minus 38 weeks. We used the week of marriage and the week of conception as references to study seasonality. We found a minor seasonal pattern in time to pregnancy when using the week of marriage as a reference. The proportions of women with a short time to pregnancy were highest during December-January and June-July, indicating that these may be the most fecund periods. In contrast, we found an obvious seasonal pattern when using the date of conception as a reference. This pattern can be largely explained by a strong seasonal pattern in pregnancy planning (in this case, in marriages). When studying seasonal variation in the time to pregnancy, the date of onset of the time to pregnancy should be used as reference, not the date of conception. Otherwise, results will be biased owing to seasonality in pregnancy planning. The same is true for studies on seasonally bound exposures in relation to time to pregnancy.

Adolescent↗
PubMed1990

[Development of visual evoked potentials in guinea pigs].

The development of visual evoked potential (VEP) was studied in guinea pigs as a function of age. Ten newborn guinea pigs from 3 litters were used, and experiments were carried out with the animals over an age span ranging from 1 to 90 days. Periodic recordings were obtained at 5 day intervals from the first up to the twentieth day after birth and at 30 day intervals from the thirtieth to ninetieth day after birth. The results were as follows: 1) The VEP comprised 7 peaks at the first day after birth, while after the fifth day it was composed of 9 peaks. 2) During the development of the guinea pigs, the latencies of VEP decreased. The reduction of the latencies of peak N2 amounted to about 25% from the first to the thirtieth day. 3) The amplitude of the initial negative spike increased from the first to the fifth day after birth, and decreased after the fifth day.

Age Factors↗
PubMed2005

Comparisons of Holsteins with Brown Swiss and Jersey cows on the same farm for age at first calving and first calving interval.

Our objective was to evaluate breed differences for heat-stress resistance as reflected by age at first calving and first calving interval. We examined the effect of geographic location and birth season on age at first calving, and geographic location and first calving season on first calving interval on Holsteins and Jerseys, and Holsteins and Brown Swiss located on the same farm. We defined 7 regions within the United States: Northwest, Central north, Northeast, Central, Central south, Southwest, and Southeast, and analyzed 7 individual states: Ohio, Wisconsin, Oregon, California, Arizona, Texas, and Florida. Brown Swiss were older than Holsteins at first calving (833 +/- 2.4 vs. 806 +/- 2.0 d in regions, and 830 +/- 3.1 vs. 803 +/- 2.4 d in states), but Holsteins and Brown Swiss did not differ for first calving interval. Jerseys were younger than Holsteins at first calving and had shorter first calving intervals. In data from individual states, Holsteins housed with Brown Swiss were older at first calving than were Holsteins housed with Jerseys (800 +/- 2.7 vs. 780 +/- 2.5 d). Holsteins housed with one breed or the other were analyzed as a separate data set, and referred to as "type of Holstein." The interaction of "type of Holstein" with first calving season was highly significant for first calving interval. Geographic location and season effects were smaller for Jerseys than for Holsteins; thus, Jerseys showed evidence of heat-stress resistance with respect to Holsteins. Management modified age at first calving in Holsteins to more nearly match that of the other breed. Longer calving intervals might be partly due to voluntary waiting period to breed the cows.

Aging↗
PubMed2002

Oral contraceptive use before first birth and risk of breast cancer: a case control study.

BACKGROUND: The aim of this study was first, to investigate whether women starting oral contraceptive (OC) use at a young age and before first birth have an increased risk for breast cancer and second, to report difficulties encountered in studying long-term health impacts of medical technologies. METHODS: Breast cancers occurring up until 1997 among 37153 Helsinki students born between 1946 and 1960 were identified by record linkage from the Finnish Cancer Registry; for each cancer case, five age-matched random controls were picked from the same student population. Those who had used the Helsinki Student Health Service (HSHS) at least three times (150 cases and 316 controls) form the final study subjects. Data on OC use and background characteristics were collected from patient records, and data on live births were derived from the population register. Odds ratios (OR) were adjusted for number of births, smoking and sports activity. RESULTS: Compared to the few non-users, OC users had a higher risk of breast cancer: the adjusted OR was 2.1 (95% confidence interval 1.1-4.2). Among OC users, no statistically significant differences in risk of breast cancer were found in regard to starting age or first birth, but small numbers made confidence intervals wide. Even though we had chosen students to be our study group, the population turned out to be unsuitable to answer our research question: most women had started their OC use old (at the age of 20 or later) and there were very few unexposed (almost all had used OC and before their first birth). CONCLUSIONS: Because adoption of the modern pattern of OC use was not common among students, it is unlikely that the impact of early and extended OC use can be studied before 2010, when women born in the 1960s are 40 to 50 years old.

Journal Article↗
PubMed2000

Delayed-interval delivery: extended series from a single maternal-fetal medicine practice.

OBJECTIVE: Our purpose was to review the extended experience of a single maternal-fetal medicine practice with delayed-interval delivery. STUDY DESIGN: We completed a retrospective review of our maternal-fetal medicine practice database from January 1991 through March 1999. Patients were derived from both primary and consultative practices. All patients were managed with tocolysis, antibiotics, and cerclage after delivery of the first fetus(es). Retained siblings were investigated by amniocentesis to exclude intra-amniotic infection. RESULTS: Twenty-four consecutive patients had attempted delayed-interval delivery. Exclusion criteria for delayed-interval delivery included monochorionicity, abruptio placentae, severe preeclampsia, and the need for hysterotomy. The mean latency interval was 36 days, with a range of 3 to 123 days. Additionally, patients with previous cerclage(s) had significantly shorter mean latency intervals than patients without previous cerclage(s). Patients with long latency intervals (> or =49 days) had earlier births of the first fetus. CONCLUSION: Selected multichorionic pregnancies may benefit from delayed-interval delivery. Patients with previous cervical cerclage(s) during the index pregnancy are less likely to achieve significant latency intervals. Even modest intervals between births of siblings at critical gestational ages can improve neonatal survival and decrease neonatal morbidity.

Cervix Uteri↗
PubMed2000

The relative importance of gestational gain and maternal characteristics associated with the risk of becoming overweight after pregnancy.

OBJECTIVES: To assess the relationships between gestational gain, race/ethnicity, reproductive history, age, education and the risk of becoming overweight after pregnancy. STUDY DESIGN: Prospective cohort study of adult women from four race/ethnicity groups who had two consecutive births between 1980 and 1990 at the University of California, San Francisco (UCSF). MEASUREMENTS: Height and pregravid weights for each pregnancy were self-reported. Women were classified as overweight or not overweight according to the Institute of Medicine (IOM) criteria for pregnancy. Gestational gain was defined as the difference between the pregravid weight and the last weight before delivery of the first study pregnancy. SUBJECTS: 1300 healthy women aged 18-41 y who had a singleton, full-term, live birth (index or first study pregnancy) followed by a second birth. Self-reported pregravid weights and heights were used to calculate body mass index (BMI). Women with a pregravid BMI below 26.0 kg/m2 before the index pregnancy were classified as not overweight (n = 1128). Overweight status following the index pregnancy was based on pregravid BMI for the second pregnancy. RESULTS: Seventy-two women (6.4%) became overweight following the index pregnancy. Statistically significant independent predictors of the risk of becoming overweight included: maternal age 24-30 vs above 30 y, high gestational gain, short interval from menarche to first ever birth ( < 8 y), and young age at menarche ( < 12 y). The risk of becoming overweight was increased 2.5-3 times for each of these risk factors. Whites were 4.5 times more likely to become overweight than Asians, but blacks and Hispanics did not appear to differ from whites. Parity, time interval, smoking habit, education, marital status and other factors were not associated with the risk of becoming overweight. CONCLUSIONS: These findings suggest that young age at menarche, maternal age and short time from menarche to first ever birth may be as important as high gestational weight gain in determining the risk of becoming overweight after pregnancy.

Adolescent↗
PubMed1995

Chronic polychlorinated biphenyls exposure on three generations of oldfield mice (Peromyscus polionotus): effects on reproduction, growth, and body residues.

Effects of chronic dietary exposure to low levels of PCBs (polychlorinated biphenyls) on reproduction, growth and whole body burdens were investigated in three generations of Peromyscus polionotus. Mated pairs were maintained on a diet containing 5 mg/kg PCBs (Aroclor 1254) for 12 months, beginning exposure as young adults; matched controls received a similar diet without PCBs. Offspring were maintained on the parental regime and paired at maturity with non-siblings in the same group. In first and second generation offspring, birth and weaning weights were significantly lower in PCB-exposed animals; in the second generation, there were also significantly fewer mice born/month, longer intervals prior to birth of the first litter, and decreased survival to weaning (25 days) among exposed mice. Whole body residue of PCBs increased significantly with each generation of exposure. This study clearly shows that chronic exposure to PCBs at a dosage of 5 mg/kg depressed fertility, growth and survival in Peromyscus, and that these effects were amplified through multigenerational exposure.

Animals↗
PubMed1994

Sex preference and third birth intervals in a traditional Indian society.

The traditional preference for sons may be the main hindrance to India's current population policy of two children per family. In this study, the effects of various sociodemographic covariates, particularly sex preference, on the length of the third birth interval are examined for the scheduled caste population in Assam, India. Life table and hazards regression techniques are applied to retrospective sample data. The analysis shows that couples having two surviving sons are less likely to have a third child than those without a surviving son and those with only one surviving son. Age at first marriage, length of preceding birth intervals, age of mother, and household income have strong effects on the length of the third birth interval.

Adolescent↗