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PubMed2006

Increased vascular endothelial growth factor and pregnancy-associated glycoproteins, but not insulin-like growth factor-I, in maternal blood of cows gestating twin fetuses.

Differences in placental mass and vascularity exist between cows gestating single vs. multiple fetuses. Therefore, the association between fetal number and placental development or function was assessed by comparing concentrations of vascular endothelial growth factor (VEGF), pregnancy-associated glycoproteins (PAG), IGF-I, and progesterone in the maternal blood of cattle selected for twin births and gestating 1 (n = 23) vs. 2 (n = 17) fetuses. Samples of jugular venous blood were collected serially at a mean of 57, 121, 192, and 234 d (range within groups was 20 d) after AI. Plasma concentrations of VEGF, IGF-I, and progesterone were measured by double-antibody RIA, and of PAG by an indirect sandwich ELISA. Concentrations of VEGF and progesterone were greater (P < 0.05) in dams with twin vs. single fetuses. Maternal VEGF concentrations did not differ among collection times, but progesterone concentrations increased (P < 0.01) between d 192 and 234. Conversely, PAG concentrations were low at d 57 and 121 and did not differ between dams carrying singles or twins. However, the subsequent increase (P < 0.01) in PAG was greater in dams with twins, resulting in greater (P < 0.01) PAG concentrations for dams with twins at d 192 and 234 (type of birth x time; P < 0.01). Maternal IGF-I concentrations were unaffected by fetal number. Because corpora lutea persisted for the duration of the evaluation period, maternal progesterone concentrations were likely related to the number of corpora lutea rather than the number of fetuses. It is postulated that the greater PAG and VEGF concentrations in the blood of dams gestating twins are the result of a larger uteroplacental mass, including increased numbers of binucleate cells and increased angiogenesis and vasculogenesis associated with a twin pregnancy. Although PAG and VEGF were elevated in dams gestating twins, variability within and among birth groups limits the use of PAG or VEGF measurements for the diagnosis of twins.

Animals↗
PubMedDate not supplied

The correspondence between intention to avoid childbearing and subsequent fertility: a prospective analysis.

CONTEXT: Retrospective studies of pregnancy intendedness have revealed some characteristics that can help identify which women are more likely than others to experience an unintended birth. A comparison of these findings with those from a prospective analysis may shed greater light on the characteristics associated with unintended pregnancy. METHODS: Data were taken from the 1988 National Survey of Fertility Growth and a telephone reinterview of respondents conducted in 1990. Separate analyses were conducted of women intending to postpone childbearing for at least three years and of women intending to forgo all future childbearing. Logistic regression models were used to identify the effects of social and demographic characteristics, as well as change in marital status and certainty of intentions, on the odds of experiencing a birth in the interval between interviews. RESULTS: Only 10% of women intending to postpone pregnancy for more than three years and 8% of respondents seeking to forgo future childbearing had a birth in the interval between interviews. (These births, referred to as unpredicted births in this article, are roughly analogous to those labeled unintended in retrospective analyses.) Women with incomes below the poverty level were 2-3 times as likely as women with incomes between 100% and 199% of poverty to experience an unpredicted birth. Race was not a significant factor among women intending to avoid future childbearing, and became nonsignificant among those intending to postpone when change in marital status and contraceptive status were taken into account. Women aged 35 and older who wanted no more children were significantly less likely than women aged 20-29 to have an unpredicted birth. Women aged 30-34 who wanted to postpone childbearing were roughly 70% less likely than women aged 20-29 to experience an unpredicted birth. Overall, women who were at risk for a pregnancy but not practicing contraception were 2-3 times more likely than women using an effective method to have an unpredicted birth. CONCLUSIONS: There are at least two potential explanations for instances where the correlates of unintended births in the prospective analysis differ from those identified in retrospective studies. Certain subgroups of women may be more likely to classify births as wanted when they are asked retrospectively; alternatively, they may be more likely to experience changes in their living conditions that alter their fertility intentions.

Adolescent↗
PubMed1989

[Overlying cultural factors: the saturation of tensions as an explanation of fertility decline in Switzerland].

"The purpose of this article is to provide an explanation of the recent decline of fertility in Switzerland with a saturation model. This process, which can be observed in the majority of highly developed countries since about 1965, is part of a long-term process of limitation of births." Factors considered in the model include the segregation between the work place and household, the development of social security systems, excessive consumption, and changing values. The model attempts to show that individuals are experiencing increasing structural and cultural tensions due to an increase in the impact of such factors that lead them to react in a variety of ways, some of which can affect the number and timing of births. The author suggests that both the fertility level and fertility decline have different determinants and concludes that fears of the "dying out" of the Swiss population are premature. (SUMMARY IN ENG AND FRE)

Behavior↗
PubMed1987

[A case study on the fertility and contraceptive practice of urban women].

"This study analyzes the fertility characteristics and the practise of contraceptive methods among married women aged 15-49 living in Izmit [Turkey] urban area. While the average pregnancies and the number of living children are lower than the average for overall Turkey, the use of contraceptive methods [is] found to be higher. Only [one third] of the women exposed use traditional methods. No significant relation is found between education level or number of living [children] and use of contraceptive methods. 66.5% of all women agree that due to medical or social reasons, legal abortions must be made in hospitals." (SUMMARY IN ENG)

Abortion, Induced↗
PubMed1990

Prenatal care evaluation and cohort analyses.

The value of prenatal care has been obscured by multiple factors, including the limitations of birth certificate data, large socioeconomic disparities between women who seek prenatal care and those who do not, and the "preterm delivery bias", ie, the reduced pregnancy duration and opportunity for prenatal care among women who give birth prematurely. Perinatal mortality and morbidity (neonatal intensive care unit admission; ventilator therapy) were carefully assessed in an indigent population (28,838 deliveries at Parkland Memorial Hospital). To avoid the preterm delivery bias, a cohort of all women whose pregnancy reached a specific week of gestation was identified and their prenatal care status (zero vs one or more visits) by that week was related to pregnancy outcome. Separate cohorts were defined at 26, 30, 34, 38, and 42 weeks. Prenatal care was associated with improved pregnancy outcomes in only the 34-, 38-, and 42-week cohorts (P less than .01). Findings suggest substantial benefit from prenatal care after 30 weeks' gestation but not from early prenatal care. Unfortunately, it may not be possible to assess prenatal care accurately in observational studies even if cohort analyses are used. Clinical trials are needed to assess the effects of strategies for increasing or improving prenatal care, especially in early pregnancy.

Adolescent↗
PubMed1990

Acid-base balance and lactatemia in acute hypoxia in normoxic or hypoxic albino rats.

Albino rats Wistar family were raised since birth in normobaric hypoxic environment (10% O2 in N2). This hypoxic animal group and a normoxic control group were subjected to acute hypoxia in two spaced tests. The rats were exposed for 15 minutes to 7% O2 and later to 5% O2 gas mixture. At the end of the test with 7% O2 the hypoxic animals since birth showed a smaller quantity of blood lactate and their acid-base balance was more acid when compared to control animals. These differences were significant. In the considered metabolic parameters the differences between the 2 groups became not significant at the end of the test with 5% O2. We believe that the found differences in mentioned parameters between hypoxic and normoxic animals, also according to cellular adaptative processes, occurred during the rearing in hypoxic environment. In the test with 5% O2 the seriousness of the hypoxia overcomes the effects of adaptative mechanisms in hypoxic animals since birth. We believe that hypoxic rats since birth represent, limitedly to some aspects, different metabolic models compared to normoxic animals.

Acid-Base Equilibrium↗