SEARCH · PubMed Health

Results for “Lactation, Prolonged”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources

PubMed1982

Serum prolactin levels in undernourished Indian lactating women.

1. Serum prolactin (PRL) levels, both basal and post-suckling peak, were estimated in fifty-seven lactating women. 2. Basal PRL levels were significantly higher in all lactating women irrespective of the duration of lactation as compared to the levels in non-pregnant, non-lactating women. 3. There was significant positive correlation (r 0.69, P less than 0.001) between the basal PRL levels and the post-suckling peak values. 4. After 8 months of lactation, peak post-suckling, PRL levels were not significantly different from basal values. 5. Basal PRL levels were significantly lower (P less than 0.05) in mothers whose infants were being supplemented. 6. PRL levels were not related to the mother's nutritional status as determined by body-weight. 7. The findings suggest that high PRL levels during lactation prolong the duration of lactional amenorrhoea and hence the relative infertility.

Adult↗

PubMedDate not supplied

Trace-element status in milk and plasma of Kuwaiti and non-Kuwaiti lactating mothers.

There is a wide variation in the reported data on the concentrations of trace elements in human milk from different countries, but such data are not available for Kuwait. The objective of this study was to analyze the concentration of zinc, copper, manganese, and iron in milk and plasma of Kuwaiti and non-Kuwaiti mothers during prolonged lactation. Milk samples (from 34 donors) were collected early in the morning before feeding the infant. Trace elements were analyzed using atomic absorption spectrophotometry. Protein content and activity of superoxide dismutase were assayed spectrophotometrically. Concentration of zinc, copper, iron, and total protein and activity of superoxide dismutase in milk and of only zinc in plasma of Kuwaiti mothers were significantly higher than those of non-Kuwaitis. Concentration of zinc, copper, manganese, and total protein in milk of both groups decreased as lactation continued but that of milk iron and plasma trace elements remained unchanged. The data of Kuwaiti mothers are consistent with those of previous reports on hyperuricemia, and the prevalence of obesity was found to be higher in the Kuwaiti population than in other countries. High protein content in association with high concentration of trace elements in milk of Kuwaiti versus non-Kuwaiti mothers may indicate that protein content in milk is an important determining factor for the concentration and bioavailability of these elements.

Adult↗

PubMed1975

Ultrastructural studies on the hypothalamic neurosecretory neurons of the rat. III. Paraventricular and supraoptic neurons during lactation and dehydration.

The ultrastructural features of paraventricular (PVN) and supraoptic (SON) neurons and of their axons were studied in lactating and dehydrated rats. Under both conditions of stimulation, the PVN and SON neurons and their axons enlarge. The protein synthesizing apparatus of the neurons becomes activated, but the number of neurosecretory granules (NSG) is decreased. No differences are seen between the PVN and SON neurons during lactation or dehydration. The similarity and simultaneity of the response of the PVN and SON neurons to these two different stimuli is discussed in the light of the theory of nuclear and neuronal specialization for the production of only one hormone. After prolonged lactation of over 2 1/2 weeks' duration, neurons with extreme vacuolation of the rough endoplasmic reticulum (RER) appear in the PVN and SON; the vacuolated neurons appear earlier and predominantly in the PVN involving a maximum of 10-15% of all PVN neurons. Vacuolated neurons were never seen in either nucleus during dehydration of up to 6 days' duration. The vacuolation is suggested to represent an exhaustion phenomenon due to an intense, long-lasting stimulus for oxytocin synthesis. The predominant location of the vacuolated neurons in the PVN supports the theory that oxytocin is produced predominantly in the PVN. The decrease in the number of NSGs during these states of enhanced hormone secretion is considered to corroborate the proposed existence of an extragranular fast axoplasmic transport mechanism in PVN and SON neurons. The possible existence of a reuptake mechanism into NSGs, similar to that in the vesicles of monoaminergic nerve endings is discussed.

Animals↗

PubMed1997

Lactation and breast cancer risk.

Breast cancer is a common disease with few practical preventive measures. The recent evidence that lactation, like other reproductive experiences, is associated with a modest reduction in breast cancer risk is therefore of great interest. Overall, the reduction in risk appears to be about 20% for ever breast feeding and is even greater for women with histories of prolonged lactation, or who initiate breast feeding at young ages. In many studies this risk reduction seems to be limited to premenopausal women. It appears unlikely that this inverse association is attributable either to higher risk among women who use lactation suppressants or who have difficulty either starting or continuing breast feeding. While a strong or consistent protective effect of lactation on breast cancer risk has not been observed in some large and well conducted studies, this likely reflects the limited breast feeding practices among modern women. If early, exclusive and extended breast feeding is necessary to achieve a breast cancer risk reduction, future studies among U.S. women may be unable to clarify this association.

Adult↗

PubMed1979

The concentrations of copper and zinc in human milk. A longitudinal study.

Twenty-seven healthy Finnish mothers were followed during the course of their entire lactation period. A total of 229 individual milk samples, collected in the beginning and at the end of each feed during a 24-h period, were obtained from the 2nd week to the 9th month of lactation. The copper and zinc concentrations were determined by atomic absorption spectrophotometry. The concentrations of the trace-elements investigated were dependent on the stage of lactation. The median copper and zinc concentrations decreased during the course of lactation from about 0.60 mg/l and 4.0 mg/l to 0.25 mg/l and 0.5 mg/l, respectively. The importance of considering the stage of lactation in the evaluation of the trace-element nutrition value of breast milk should be emphasized. The calculated means of the concentrations of these trace-elements in mature human milk presented in the literature seem to overestimate the actual levels in prolonged lactation.

Breast Feeding↗

PubMedDate not supplied

Production of milk and nutrition of the dependent young of free-ranging koalas (Phascolarctos cinereus).

The production of milk by lactating females, and energy expenditure and foliage intake of their dependent young, were investigated in free-ranging koalas. Koalas had the lowest mass-specific daily milk-energy production at peak lactation so far recorded in a mammal, but the duration of reproduction was 58% longer than the combined marsupial and eutherian average. As a consequence, the total energy input to reproduction in koalas was similar to that in other mammals. We propose that the prolonged lactation and low daily rate of energy transfer to the young by female koalas is an adaptation to the low energy availability from their diet of Eucalyptus foliage. Energy requirements (field metabolic rates) of young koalas were lower than those expected for typical marsupials (only 60% at permanent pouch exit), which may be a necessary preadaptation that allows the low rate of maternal energy transfer. However, the energy requirements of the adult females were no lower than expected for marsupials. This pattern of energy requirements and age resulted in a linear relationship between field metabolic rate and mass for the koalas in this population. Differences in milk production between the years of the study coincided with fluctuations in the availability of preferred young foliage, which suggests that lactational output by koalas may be flexible and affected by diet quality. Despite the interannual differences in milk production, growth of the young was similar in the two years.

Aging↗

PubMed1996

[Sequential observations of brain edema with proton magnetic resonance imaging and spectroscopy].

The purpose of this study was to assess the relationship between morphological and metabolic changes in brain edema using proton magnetic resonance systems. The serial changes during the first 24 hours in the cold-injury trauma rat brain model were investigated by proton magnetic resonance imaging (1H MRI) and high-resolution proton MR spectroscopy (1H MRS). We also analyzed the efficacy of AVS 1,2-bis (nicotinamide)-propane which can scavenge free radicals to the edema in this experiment. The edema was developing extensively via the corpus callosum in ipsi- and contralateral hemispheres as shown by gradually increased signal intensity on 1H MRI. 1H MRS initially showed accumulation of acetate and lactate, and transient increasing of glutamine. After 24 hours, the increased glutamine decreased below the control, alanine increased, and N-acetyl asparatate decreased with the edema development. AVS-treatment significantly suppressed edema development, increases of lactate and alanine and decreases of N-acetyl asparatate. We suggest that the cold-induced lesion contains anaerobic glycolysis deterioration and results in severe brain tissue breakdown. AVS is proved valuable for the treatment of this edema lesion. Clinical 1H MRS showed prolonged lactate elevation and significant decreases of other metabolites in human ischemic stroke edema. In peritumoral edema, decreased N-acetyl asparatate gradually improved, and slightly elevated lactate disappeared after tumor removal. 1H MRS feasibly characterizes the ischemic and peritumoral edema and makes a quantitative analysis in human brain metabolism. We believe the combined 1H MRI and MRS study is a practical method to monitor the brain conditions and will make it easy and possible to find new therapeutic agents to some brain disorders.

Aged↗

PubMed1985

The effects of a dietary zinc supplement during lactation on longitudinal changes in maternal zinc status and milk zinc concentrations.

Dietary zinc intakes, selected biochemical indices of zinc status, and milk zinc concentrations were determined at monthly intervals throughout lactation for 53 middle-income lactating women, 14 of whom received a daily supplement of 15 mg zinc. Overall mean dietary zinc intake for the non-supplemented group (NZS) was 10.7 +/- 4.1 mg/day (mean +/- SD). The mean dietary zinc intake of the zinc supplemented group (ZS) was 12.2 +/- 3.5 mg/day, with an additional 12.8 +/- 1.5 mg/day from the supplement. For the NZS group, the highest mean plasma zinc concentration of 79 +/- 10 mu/dl, which occurred at month 4, was significantly less than the mean for non-lactating control women (86 +/- 10 micrograms/dl). ZS plasma zinc levels had a pattern similar to that of the NZS group for months 1-7. The rate of decline in milk zinc during lactation was significantly less for the ZS group compared to that of the NZS group (p = 0.02). It is concluded that milk zinc concentrations are influenced by maternal zinc intake within a physiological range and that the effects of low maternal intakes are most apparent with prolonged lactation.

Adult↗

PubMed1994

The Lactational Amenorrhea Method (LAM): a postpartum introductory family planning method with policy and program implications.

It is well accepted that breastfeeding contributes significantly to child survival and child nutrition. Healthful child spacing is associated with improved birth outcomes and maternal recovery. On a population basis, breastfeeding may contribute more to birth spacing than all family planning use combined in many countries. However, while breastfeeding does provide a period of infertility, until recently, there was no reliable way for an individual woman to capitalize on this lactational infertility for her own efficacious child spacing. The Lactational Amenorrhea Method (LAM) is a new introductory family planning method that simultaneously promotes child spacing and breastfeeding, with its optimal nutrition and disease preventive benefits for the infant. LAM, as it is called, is based on the utilization of lactational infertility for protection from pregnancy and indicates the time for the introduction of a complementary family planning method. LAM is recommended for up to six months postpartum for women who are fully or nearly fully breastfeeding and amenorrheic, and relies on the maintenance of appropriate breastfeeding practices to prolong lactational infertility, with the concomitant delay in menses return. A recent clinical trial confirmed the theoretical 98% or higher effectiveness of the method and field trials are demonstrating its acceptability. Nonetheless, some demographers and family planning organizations continue to debate its value. The development, efficacy, and sequelae of the method are presented using data from several studies by the authors.

Amenorrhea↗

PubMed1993

Lactate and postischemic recovery of energy metabolism and electrical activity in the isolated perfused rat brain.

The aim of the present study was to evaluate whether lactate can maintain the energy metabolism and electrical activity of isolated perfused rat brain in the absence of glucose. To exhaust cerebral glucose stores and simultaneously raise endogenous lactate, complete ischemia was induced. After ischemia, when a glucose-free perfusate was supplied, restoration of interstitial potassium (Ke+), cortical discontinuous current (DC) potential, electroencephalogram (EEG) activity, and ATP and phosphocreatine (PCr) was not significantly different from postischemic recovery findings when a glucose-containing perfusate was used. In the group receiving glucose-free perfusate, postischemic application of 1 mM iodoacetic acid did not inhibit the recovery of electrical activity, Ke+, or DC potential. After recovery of Ke+ in glucose-free reperfusion, a 20-30-Hz EEG pattern appeared and was maintained for about 20 min followed by disappearance of spontaneous electrical activity. An abrupt increase of Ke+, a steep negative DC shift, and a substantial decrease of ATP and PCr occurred after about 22 min of reperfusion. During the first 5 min of glucose-free reperfusion, consumption of lactate was significantly higher (0.89 mumol/g wet weight/min) than during reperfusion with medium containing glucose (0.41 mumol/g ww/min). Increasing amounts of tissue lactate prolonged maintenance of electrical function in glucose-free reperfusion. This correlation could not be found for free fatty acids. In conclusion, after a few minutes of ischemia, the brain is able to recover cellular ion transport and electrical activity without a supply of glucose, preferentially by combustion of lactate accumulated in brain tissue. This mechanism is only useful during a limited time period until the lactate accumulated during ischemia is combusted.

Animals↗

PubMed1978

[Mechanism of mammary cancer regression in lactating rats].

Dependence of the incidence of regression of the transplantable carcinoma of the mammary gland RMK-1 in albino rats on lactation conditions was studied. The tumour was subject to regression in 47% of the animals nursing 8 +/- 1 ratlings. Following ovariectomy and cortisone and oxytocine administration which produced mediated inhibitory effect of FSH secretion of the hypophysis the frequency of the tumour regression in rats nursing the same number of ratlings rose to 71--81%. In rats with prolonged lactation nursing 8 +/- 1 ratlings for 2--2.5 months and in rats with intensive lactation nursing 13 +/- 2 ratlings the tumour regression practically failed to occur. The data obtained confirmed the suggestion that along with high LTH of the hypophysis secretion of importance for regression of mammary carcinoma in the course of lactation was reduction of the secretion of FSH of the hypophysis.

Animals↗

PubMedDate not supplied

Influence of lactation history on breast nipple aspirate fluid yields and fluid composition.

Analysis of nipple aspirate fluid (NAF) can be useful for understanding the impact that various lifestyle factors have on the biology of the breast. In this study, breast NAF was obtained at baseline from premenopausal women who volunteered for a dietary intervention trial. The influence of lactation history on both fluid yields and fluid composition was explored. We examined the levels of fat-soluble micronutrients (tocopherols, carotenoids, retinol), one lipid oxidation product (8-isoprostane), cholesterol, and protein in NAF. Roughly half of the women in the trial had never lactated, but this did not affect fluid yields appreciably. Carotenoid and tocopherol levels were significantly higher in NAF from women who lactated 6 months or more versus women who had lactated for shorter periods of time or never, but 8-isoprostane, protein, and cholesterol levels were not affected appreciably by lifetime lactation history. Longer times after weaning were associated with higher cholesterol levels, and there also was a suggestion the fat-soluble micronutrients declined with time after weaning. This is of interest since high cholesterol levels in breast fluid have been associated with an increased breast cancer risk, while carotenoids and tocopherols are thought to be protective. The results of this study provide further evidence of the potential benefits of prolonged lactation via its influence on NAF composition.

Adult↗

PubMed2001

Body weight loss during lactation and its influence on weaning-to-service interval and ovulation rate in Landrace and Yorkshire sows in the tropical environment of Thailand.

The aim of this study was to investigate the ovulation rate and the weaning-to-service interval (WSI) of sows in relation to their body weight loss during lactation in tropical climatic conditions. Effect of lactation length (LL), number of total born piglets, number of live born piglets, litter birth weight, average piglet birth weight, number of pigs weaned, litter weaning weight and average pig weaned weight on sow weight loss during lactation were also studied. This study was conducted in two commercial purebred sow herds (A, B) in the central part of Thailand from August to December 1997. The herds had both Landrace (L) and Yorkshire (Y) sows. The 123 sows (55 L and 68 Y) in herd A and 153 sows (95 L and 58 Y) in herd B, parity 1-4, were weighed within 4 days after farrowing and at weaning. Lactation length, litter size at birth and at weaning, litter weight at birth and at weaning, and WSI were recorded for each of these sows. In herd A, 52 sows (20 L and 32 Y) were examined once by laparoscopy between days 8 and 14 after AI-service. These sows had farrowed at least seven piglets in the previous parturition. The numbers of corpora lutea (CL) in both ovaries were counted, and were assumed to equal the ovulation rate. L-sows had significantly (P < 0.05) higher relative weight loss during lactation (RWL) than Y-sows. The RWL increased by 0.7% for each extra pig weaned. When LL increased by 1 day, within the interval of 17-34 days, RWL decreased by 0.6%. Sows with a high weight loss had significantly (P < 0.05) longer WSI than sows with medium or low weight loss. Weight loss had a significant (P < 0.05) effect on WSI in parity 1 and 2 sows. Y-sows had more CL than L-sows (15.7 versus 14.0) (P < 0.05). RWL, parity and regression on lactation length had no significant effect on number of CL. In conclusion, sows with higher number of pigs weaned lose more weight. Under the restricted feeding regime applied, high weight loss during lactation prolongs WSI in parity 1 and 2 sows, but has no influence on the ovulation rate at first oestrus after weaning. The ovulation rate is higher in Yorkshire than in Landrace sows. The ovulation rate is independent of parity.

Animals↗

PubMed1984

Stimulation of milk secretion with inhibition of milk ejection by corticosteroids during extended lactation in the rat.

Milk yield declined significantly between days 22 and 28 of lactation in rats, when lactation was extended by frequent replacement of older litters with younger ones. Corticosterone implants but not cortisol injections or implants prevented this decline. Cortisol, however, appeared to inhibit milk ejection since the mammary glands became engorged with milk and milk yield was improved dramatically by oxytocin injections. In both cases corticosteroid concentrations increased approximately threefold above basal concentrations. Both corticosteroids increased total mammary gland RNA content and lipoprotein lipase (LPL) activity of the mammary gland but were without effect on insulin binding. They also decreased LPL activity, lipogenesis and the number of insulin receptors on adipose tissue. Serum prolactin and insulin concentrations were unaffected by any of the treatments. The results suggest that corticosteroids inhibit milk ejection under certain conditions, may be circulating in lower concentrations, which thereby limit milk production, during prolonged lactation and may improve milk yield during extended lactation in part by suppressing anabolic activity in adipose tissue.

Adipose Tissue↗

PubMed1991

Mechanism of action of progesterone as contraceptive for lactating women.

Progesterone vaginal rings releasing 5-15 mg/day were tested as a contraceptive for lactating women. Progesterone plasma levels achieved ranged from 10 to 20 nmol/L. Pregnancy rates at the end of the year were less than 1% and 39% in treated (n = 210) and untreated (n = 236) nursing women, respectively. Around 70% of treated and 30% of untreated women were amenorrheic at 8 months post partum. The endocrine profile during the first 8 months post partum was assessed in 36 treated and 28 untreated nursing women. Pre- and postsuckling prolactin (PRL) levels were measured at 1600 hr at fortnightly intervals and E2 determinations and ovarian ultrasound were performed twice a week. Prolactin increases in response to suckling and postsuckling PRL levels were higher, E2 levels were lower, and follicular growth was arrested at earlier stages in progesterone-treated than in untreated women. The pattern observed in progesterone-treated women was similar to that in prolonged lactational amenorrhea. This suggests that progesterone increases the sensitivity of the breast-hypothalamic-pituitary system to suckling and reinforces the mechanism of lactational infertility.

Breast Feeding↗

PubMedDate not supplied

Vaginal rings for contraception in lactating women.

Contraceptive methods for breastfeeding women should be safe for the mother and infant and should not interfere with lactation. Progestin-only methods meet these conditions and can be used from the sixth week postpartum. Because all progestins are excreted in milk, those that are insufficiently active by the oral route are preferable to avoid any possible effect on the baby. These steroids, however, must be administered to the mother by a non-oral route. Initially, progesterone was administered subdermally to test this concept. Subsequently, a progesterone vaginal ring was developed to be used continuously for 3 to 4 months and replaced with a new device, as needed, until weaning. Clinical trials have shown a high contraceptive efficacy (over 98.5%) and safety. The gross continuation rate of this method is approximately 40% at 12 months of use, with use-related problems being the main reason for discontinuation (26.8%). Currently, a Nestorone vaginal ring is under development, delivering 50 microg of Nestorone per day. It may be used continuously for up to one year, even if weaning occurs earlier. Both of these progestin-only rings prolong lactational amenorrhea to 10 to 12 months, which represents a health benefit and convenience for many women. The registration of the progesterone vaginal ring, developed as a contraceptive method to be used exclusively during lactation, has been approved in Chile and Perú. The fact that it is a user-controlled long-term contraceptive that delivers a natural hormone makes it an attractive option for many women.

Administration, Intravaginal↗

PubMedDate not supplied

Interplay of pregnancy, lactation, and hyperthyroidism leading to severe osteoporosis in a young woman.

OBJECTIVE: To describe the case of a young woman who had severe osteoporosis due to the compounding effects of pregnancy, lactation, and hyperthyroidism and who had a presumed metastatic lesion in the lumbar spine. METHODS: We present the clinical, pathologic, radiologic, and laboratory findings and describe the clinical course of our patient. RESULTS: A 31-year-old Arabic woman was referred to the M. D. Anderson Cancer Center because of a lytic lesion in her lumbar spine, presumed to be metastatic deposits. She had a history of two consecutive pregnancies and intermittently treated hyperthyroidism. Our initial evaluation revealed that the patient had clinical and biochemical thyrotoxicosis, and we treated her with thionamides, corticosteroids, and radioiodine ablation. Radiologic studies disclosed a complex renal cyst that had increased uptake on a bone scan, which was highly suggestive of a primary malignant lesion. Ultimately, however, it proved benign on pathologic analysis after a left nephrectomy. Bone mineral density measurements identified severe osteoporosis (T-scores: lumbar spine, -3.3; right hip, -2.2; and left hip, -2.0), which had led to vertebral collapse and was misinterpreted as malignant metastatic disease. The bone mineral densities improved (+5 to +11% at the various sites) within 4 months after definitive treatment and cure of the hyperthyroidism. CONCLUSION: The effect of pregnancies and prolonged lactation, in the milieu of other risk factors for bone depletion such as hyperthyroidism, may cause severe osteoporosis in a young patient. The resulting osteoporosis may manifest as a lesion suggestive of malignant metastatic involvement.

Adrenal Cortex Hormones↗

PubMed1993

Myocardial lactate release during prolonged exercise under hypoxaemia.

The possible appearance of myocardial lactate production during exercise under hypoxaemia, simulating an altitude of about 4500 metres above sea-level (masl) was investigated. Twelve healthy men were studied, after coronary sinus catheterization, during prolonged exercise breathing 12% O2 compared with men breathing air. Coronary sinus blood flow was measured by thermodilution. Exercise duration under each breathing condition was 30 min and the order normoxaemia/hypoxaemia was varied between subjects so as to compensate for any influence of a preceding exercise period on a subsequent one. Work load was adjusted so as to produce a heart rate (HR) of 130-140 beats min-1 during both hypoxaemia and normoxaemia. [14C]lactate was infused at a constant rate i.v. throughout the study to detect a possible myocardial lactate release simultaneously with a net uptake. Myocardial O2 uptake did not differ significantly between hypoxaemia and normoxaemia. The compensation for reduced blood oxygen content was achieved entirely by a greater coronary blood flow. Yet, the arterial-coronary sinus (a-cs) lactate difference was lower during hypoxaemia than normoxaemia and isotope data indicated that this was caused by a myocardial lactate release of approximately 90 mumol min-1 which was at hand during hypoxaemia but not normoxaemia, whether hypoxaemic exercise preceded or succeeded normoxaemic exercise. In conclusion, A 27% reduction in arterial oxygen saturation is almost compensated for by an increased coronary blood flow. However, during hypoxaemic exercise cardiac energy demand is to a smaller part, about 1%, covered by anaerobic metabolism.

Adult↗