PubMed · 11558513
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C Bakoula, N Matsaniotis. 2001-02-24. Why choose caesarean section?. https://doi.org/10.1016/s0140-6736(05)71427-6
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Sustained bouts of maternal exercise during pregnancy cause an acute reduction in oxygen and nutrient delivery to the placental site. The decreased flow also initiates a slight fall in intervillous and fetal pO2 which initiates a fetal sympathetic response. This, coupled with hemoconcentration and improved placental perfusion balance, maintains fetal tissue perfusion and oxygen uptake. Exercise training during pregnancy (regular bouts of sustained exercise) increases resting maternal (and perhaps fetal) plasma volume, intervillous space blood volume, cardiac output and placental function. These changes buffer the acute reductions in oxygen and nutrient delivery during exercise and probably increase 24 h nutrient delivery to the placental site. Thus, the effect of any given exercise regimen on fetal growth and size at birth is dependent on the type, frequency, intensity and duration of the exercise as well as the time point in the pregnancy when the exercise is performed. Maternal carbohydrate intake is yet another modifying factor. Beginning a moderate exercise regimen increases both anatomic markers of placental function and size at birth while maintaining a rigorous exercise regimen throughout pregnancy selectively reduces growth of the fetal fat organ and size at birth. Likewise, decreasing exercise performance in late-pregnancy increases size at birth while increasing exercise performance decreases it. Finally, the infants born of exercising women who eat carbohydrates which elevate 24 h blood glucose levels are large at birth irrespective of exercise performance.
The focus of this paper is regression analysis of clustered data. Although the presence of intracluster correlation (the tendency for items within a cluster to respond alike) is typically viewed as an obstacle to good inference, the complex structure of clustered data offers significant analytic advantages over independent data. One key advantage is the ability to separate effects at the individual (or item-specific) level and the group (or cluster-specific) level. We review different approaches for the separation of individual-level and cluster-level effects on response, their appropriate interpretation and give recommendations for model fitting based on the intent of the data analyst. Unlike many earlier papers on this topic, we place particular emphasis on the interpretation of the cluster-level covariate effect. The main ideas of the paper are highlighted in an analysis of the relationship between birth weight and IQ using sibling data from a large birth cohort study.
OBJECTIVE: Our objective was to evaluate the outcomes of the hypertensive and preeclamptic pregnancies with or without fetal growth restriction (FGR). METHODS: We retrospectively studied 437 hypertensive pregnant women treated by calcium antagonists and divided in four groups: Gestational hypertension (GH) with or without FGR (GH-AGA: 244; GH-FGR: 78) and preeclampsia (PE) with or without FGR (PE-AGA: 76; PE-FGR: 39). Outcomes considered were: the need for a second-line treatment, prolongation of the pregnancy after diagnosis, duration of treatment in puerperium, gestational age at delivery, neonatal birth weight, perinatal mortality and neonatal malformations. RESULTS: A second line treatment was added in: GH-AGA: 15.4% vs. GH-FGR: 32.8%; PE-AGA: 28% vs. PE-FGR: 50%. We found a significant difference in delivery delay after diagnosis (31.3+/-5.4 vs. 20.7+/-3.4 days and 35.3+/-4.5 vs. 22.2+/-3.1; p<0.001). Gestational age at delivery was (p<0.001): 35.5+/-2.3 vs. 35.6+/-2.5 and 34.4+/-1.7 vs. 33.1+/-2.3. A significant difference in birth weight was (p<0.001): 2,271+/-759.1 vs. 1,817.59+/-396.9 and 2,196+/-685.17 vs. 1,465.80+/-441.7. Mortality was 2.56% (2 cases) for GH-FGR and 10.2% (4 cases) for PE-FGR. No neonates showed malformations. CONCLUSIONS: Gestational hypertension and preeclampsia increase the risk of low birth weight, on the other hand the fetal growth restriction is a determinant factor for the outcome of hypertensive and preeclamptic pregnancy, perinatal morbidity and mortality of the fetus and for the management and treatment efficacy of the mother.