Calcium homeostasis in pregnancy and lactation

Health effects of breast feeding for mothers: a critical review

Lactation results in a number of physiological adaptations which exert direct effects on maternal health, some of which may confer both short and long term advantages for breast feeding mothers. Breast feeding in the early postpartum period promotes a more rapid return of the uterus to its prepregnant state through the actions of oxytocin. Breast feeding may also lead to a more rapid return to prepregnancy weight. Among studies that had good data on duration and intensity of lactation, the majority show a significant association between lactation and weight loss. However, there is no evidence that lactation prevents obesity. Lactation also affects glucose and lipid metabolism. The long term effects of these adaptations are unknown but may have implications for preventing subsequent development of diabetes and heart disease. Lactation delays the return of ovulation and significantly reduces fertility during the period of lactational amenorrhoea. This process is linked with feeding patterns and may therefore be affected by practices such as scheduled feedings and the timing of introduction of complementary foods. While the evidence from epidemiologic studies is mixed, several large studies have shown that extended lactation is associated with reduced risk of premenopausal breast, ovarian and endometrial cancers. Although bone mineralization declines during lactation, repletion takes place after weaning. As a result, breast feeding does not appear to cause long term depletion of bone nor does it increase risk of osteoporosis. Many of the physiological effects of lactation are dependent on the stimulation of the hypothalamic-pituitary axis and milk removal and thus may vary with infant feeding practices. Well controlled studies are needed that include detailed information regarding infant feeding practices in addition to the total duration of any breast feeding. Future feeding recommendations should reflect careful consideration of how such practices affect both infant and maternal health.

Preterm delivery: an overview

Preterm delivery is the leading factor causing neonatal mortality and morbidity. We have conducted a PubMed literature search to obtain an update on the etiology, diagnostic problems and therapeutic considerations of preterm delivery. Approximately 5-10% of all births are premature. Preterm labor is associated with preterm rupture of membranes, cervical incompetence, polyhydramnion, fetal and uterine anomalies, infections, social factors, stress, smoking, heavy work and other risk factors. The diagnosis is made on the patients presenting symptoms, clinical findings and of progressive effacement and dilatation of the cervix. Biochemical markers of preterm delivery are of minor importance in daily clinical work. Measurement of the cervix, however, is a practical and valuable tool to predict preterm delivery. Cervical cerclage can be useful in selected cases. Antibiotics may help to prevent preterm labor in cases of known etiologic agents (e.g. preterm rupture of membranes and urinary infection). The use of tocolytic agents such as beta-sympathetic receptor stimulators can be advocated for a few days. There is evidence that their long-term use is not beneficial and could even be harmful to the fetus. Calcium channel blockers (nifedipine) and a new selective oxytocin receptor antagonist, atosiban, appear to be as effective as beta-sympathomimetic drugs on uterine contractions with fewer side-effects. Prostaglandin synthetase inhibitors such as indomethacin may prevent uterine contractions and can be used prior to the 32nd week of pregnancy. A single course of corticosteroid treatment in two doses of 12 mg betamethasone or 6 mg of dexamethasone is important for the prevention of respiratory distress between the 24th and 34th weeks of pregnancy. Multiple doses may be harmful and should be avoided. In these cases management should depend on gestation age (fetal maturity). Uterine contractions after 34 weeks' gestation are not an indication for tocolytic treatment.

Nutritional assessment and support during pregnancy

This article thoroughly updates the authors' previous review of nutritional assessment and support during pregnancy. After briefly reviewing nutrient metabolism and requirements, the authors discuss the nutritional assessment of the pregnant woman and review the nutritional support principles in hyperemesis gravidarum and other conditions that can compromise the nutritional health of mother or fetus.

Nutritional assessment and support during pregnancy

Proper nutrition during pregnancy is critically important to mother and fetus. For most healthy women, the only nutritional intervention required may be adequate iron and folate intake; however, for others, who begin pregnancy in a malnourished state or whose nutritional intake deteriorates during pregnancy, invasive nutritional support, including tube feeding or parenteral nutrition, may be indicated. To guide nutritional therapy and to avoid its potential complications, it is necessary to evaluate the patient's nutritional state. Such evaluation must focus not only on body composition and substrate reserves but also on the patient's changing nutrient requirements and any impediments to the patient's capacity to ingest and assimilate food.

Hazards of heparin: allergy, heparin-induced thrombocytopenia and osteoporosis

Heparin is the commonest mode of thromboprophylaxis used in pregnancy. It does not cross the placenta but has potential adverse effects on the mother, of which the most important is heparin-induced osteoporosis. The hazards of heparin, including bleeding, skin reactions, heparin-induced thrombocytopenia and osteoporosis are discussed and the relevant literature reviewed. Low-molecular-weight heparins have certain advantages over standard unfractionated heparins, especially in obstetrics. Their longer half-life and increased bioavailability enable once-daily injections, making them more convenient and acceptable. They are as effective as standard heparin but have a theoretically more favourable side-effect profile, providing less anticoagulant relative to antithrombotic activity. Current evidence suggests a lower incidence of heparin-induced thrombocytopenia. A reduced risk of osteoporosis is suggested but not yet proven. Although thrombo-embolism is currently the leading cause of maternal mortality in the UK, antenatal heparin prophylaxis is not given to all women with previous thrombo-embolism because of continued fears concerning heparin-induced osteoporosis. A protocol is presented with guidelines for different levels of obstetric prophylaxis depending on the perceived level of risk.

Transient osteoporosis of the hip in pregnancy

Transient osteoporosis of the hip (TOH) is an uncommon condition. This painful regional osteoporosis affects previously healthy women in the third trimester of pregnancy. It is characterized by pain in the affected hip and pronounced osteopenia of the femoral head and neck. It has a relatively short clinical course (average 6 months) and a predictably benign prognosis. Complete clinical and radiological recovery is the rule. The diagnosis is one of exclusion. The cause of the osteopenia is not known, although various aetiological factors have been implicated. A case of TOH occurring in the third trimester of pregnancy with complete recovery within 6 months postpartum is presented.

[Pathological phosphorus and calcium metabolism during pregnancy and breast feeding]

The occurrence of calcium and vitamin D deficiencies is enhanced during pregnancy and lactation. The presentation of parathyroid diseases is altered during gestation. A peculiar form of osteoporosis, pregnancy-associated osteoporosis, may be observed. Fetus and newborns suffer the consequences of all these disorders. The authors have reviewed the early detection and treatment of these diseases and emphasized their prevention.

The effect of gynecological risk factors on lumbar and femoral bone mineral density in peri- and postmenopausal women

The relationship between gynecological history and bone mineral density (BMD) of the lumbar spine and femoral neck was studied in 3126 perimenopausal women. The study population was a random, stratified sample of participants, selected from the Kuopio Osteoporosis Study, which consisted primarily of all 14,220 women aged 47-56 years in Kuopio Province in 1989. After exclusion of 1521 women reporting past or present hormonal replacement therapy (HRT), 1605 women formed the final study population. Present HRT users had significantly higher lumbar BMD but not femoral BMD, than non-hormone users. Postmenopausal status, late menarche, and bilateral oophorectomy were risk factors for low BMD. Protective factors against low BMD were increased body weight, increased number of pregnancies, as well as hysterectomy without bilateral oophorectomy. The majority (43.8%) of these operations had been performed due to the presence of leiomyomas. No significant correlation was found between nulliparity, breast-feeding or amenorrhea before the age of 30 and BMD. In the multiple regression analysis, gynecological variables could account for only 18.4-26.8% of the variance in BMD, while time since last periods, age, age at menarche, weight and hysterectomy were the most significant variables. We conclude that reproductive history gives rise to some special risk groups, to whom BMD measurements and osteoporosis prevention efforts should be directed. However, it is impossible to predict BMD by gynecological characteristics.