Early Fetal Development and the Environment: Reproductive Genetics, The Placenta, Gestational Changes of the Reproductive Tract and Breasts, Environmental Influences on Fetal Development. Fetal Diagnostic and Treatment Modalities: Ultrasound in Perinatal Medicine, Measurement of Fetal Activity, Biophysical Evaluation of Fetal Status, Acid-Base Physiology in the Fetus, Endocrine and Other Evaluations of the Fetal Environment, Evaluation of Fetal Lung Maturity. Maternal and Fetal Pathophysiology: Pregnancy Wastage, Disorders of Parturition, Normal and Abnormal Labour, Fetal Growth, Multiple Gestation, Placental Abnormalities, Maternal and Fetal Infections, Maternal Blood Group Immunization, Maternal Disorders, Neonatal Problems.

https://adc.bmj.com/content/archdischild/64/10/1524.3.full.pdf

Maternal Fetal Medicine. Principles and Practice

Significant calcium transfer from the mother to the fetus and infant occurs during pregnancy and lactation, theoretically placing the mother at an increased risk for osteoporosis later in life. During pregnancy, intestinal calcium absorption increases to meet much of the fetal calcium needs. Maternal bone loss also may occur in the last months of pregnancy, a time when the fetal skeleton is rapidly mineralizing. The calcium needed for breast milk production is met through renal calcium conservation and, to a greater extent, by mobilization of calcium from the maternal skeleton. Women experience a transient loss of approx 3–7% of their bone density during lactation, which is rapidly regained after weaning. The rate and extent of recovery are influenced by the duration of lactation and postpartum amenorrhea and differ by skeletal site. Additional calcium intake does not prevent bone loss during lactation or enhance the recovery after weaning. The recovery of bone is complete for most women and occurs even with shortly spaced pregnancies. Epidemiologic studies have found that pregnancy and lactation are not associated with an increased risk of osteoporotic fractures.

Bone mineral changes during pregnancy and lactation

The authors tested the hypotheses that maternal bone lead burden is associated with increasing maternal whole blood and plasma lead levels over the course of pregnancy and that this association is modified by rates of maternal bone resorption. A total of 193 Mexican women were evaluated (1997-1999) in the first, second, and third trimesters of pregnancy. Whole blood lead and plasma lead levels were measured in each trimester. Urine was analyzed for cross-linked N-telopeptides (NTx) of type I collagen, a biomarker of bone resorption. Patella and tibia lead levels were measured at 4 weeks postpartum. The relation between whole blood, plasma, and bone lead and NTx was assessed using mixed models. Plasma lead concentrations followed a U-shape, while NTx levels increased significantly during pregnancy. In a multivariate model, the authors observed a significant and positive interaction between NTx and bone lead when plasma lead was used as the outcome variable. Dietary calcium intake was inversely associated with plasma lead. Results for whole blood lead were similar but less pronounced. These results confirm previous evidence that bone resorption increases during pregnancy, with a consequential significant release of lead from bone, constituting an endogenous source of prenatal exposure. They also provide a rationale for testing strategies (e.g., nutritional supplementation with calcium) aimed at decreasing prenatal lead exposure.

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Impact of Bone Lead and Bone Resorption on Plasma and Whole Blood Lead Levels during Pregnancy

Although the demand for additional calcium during pregnancy is recognized, the dietary reference intake for calcium was lowered for pregnant women in 1997 to amounts recommended for nonpregnant women (1,000 mg/day), and recently (November 2010) the Institute of Medicine report upheld the 1997 recommendation. It has been frequently reported that women of childbearing age do not consume the dietary reference intake for calcium and that calcium intake in the United States varies among ethnic groups. Women who chronically consume suboptimal amounts of calcium (<500 mg/day) may be at risk for increased bone loss during pregnancy. Women who begin pregnancy with adequate intake may not need additional calcium, but women with suboptimal intakes (<500 mg) may need additional amounts to meet both maternal and fetal bone requirements. The objective of this review is to elucidate the changes in calcium metabolism that occur during pregnancy as well as the effect of maternal calcium intake on both maternal and fetal outcomes.

Role of calcium during pregnancy: maternal and fetal needs

Lactating women secrete approximately 250 mg of calcium in breast milk each day. Some of the calcium used for milk production comes from bone as women experience a transient 3-9% decrease in bone density during lactation. This loss appears to be obligatory and under hormonal regulation as lactation-induced bone loss occurs even when calcium intake is high. Bone mineral is recovered after lactation ceases or menses resume. Recovery of bone mineral appears to be complete even when pregnancies and lactations are closely spaced, and lactation does not increase future risk of osteoporotic fracture. Current data point to estrogen and parathyroid hormone-related peptide as regulating bone mobilization during lactation. The typical calcium regulatory hormones, parathyroid hormone, calcitriol and calcitonin, do not appear to stimulate bone resorption during lactation. Restoration of ovarian hormone production and decreased production of PTHrP2 are likely to result in the recovery of bone mineral after lactation has ceased.

Hormonal and dietary regulation of changes in bone density during lactation and after weaning in women

Calcium homeostasis during pregnancy and lactation in primiparous and multiparous women with sub-adequate calcium intakes

This paper presents an observatory for registering applications that use participatory sensing to collect data. Cataloging these applications will aid the scientific community to exchange more information, facilitating the comparison between different initiatives. Through an initial research, the applications are categorized in areas usually considered in the literature. We propose a survey to validate the platform and also discuss the taxonomies created as a result of this survey. The main contributions of this paper include the classification of crowdsensing applications in different ontological categories, as well as the proposal of a technology platform that enables the distributed and collaborative cataloging of crowdsensing initiatives.

Glaucia J.O. Melo

Papers

Calcium homeostasis during pregnancy and lactation in primiparous and multiparous women with sub-adequate calcium intakes

Towards an observatory for mobile participatory sensing applications

Folate and cobalamin uptake by human placenta in complicated pregnancies: prematurity, preeclampsia and fetal neural tube defects.