Corticosterone secretion in response to suckling at various stages of normal and prolonged lactation in rats.
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Adrenal Cortex Hormones↗
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Results for “Lactation, Prolonged”
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Adrenal function during prolonged lactation.
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Adrenal Glands↗
[Prolongation of the gestative bodies in the rat by prolactin; study of delivery and ablation of the gravid cornua during prolonged lactation].
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Animals↗
[Influences of prolonged lactation on the composition of human milk].
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Breast Feeding↗
Weight loss during prolonged lactation in rural Bangladeshi mothers.
To determine the duration of lactation which is associated with weight loss in rural Bangladeshi mothers and also to determine the relationship with consumption patterns of principal food items, a cross-sectional study was carried out among 791 lactating rural Bangladeshi mothers aged 18-40 years. Results were compared with 333 non-pregnant and non-lactating mothers of a similar age group. The duration of lactation was up to 60 months. The mean difference in body-weight and body mass index (BMI) of lactating mothers who breastfed their children up to 24 months was significantly lower compared to non-lactating mothers of the same age group, but no differences were observed for those who breastfed beyond 24 months. The frequency of consumption of principal food items was comparable between the non-lactating and the lactating mothers who breastfed beyond 24 months. Results of multiple linear regression analysis showed that body-weight of mothers was negatively correlated with 1-12 month(s) and 13-24 months of lactation after controlling for height, education, and food consumption (slope -1.04, p<0.05 and slope -1.23, p<0.05 respectively). Height and consumption of meat and milk were significantly positively correlated with body-weight (slope 0.53, p<0.001; slope 1.44, p<0.001; and slope 0.75, p<0.05 respectively). The study concluded that Bangladeshi women who breastfed up to 24 months were of lower weight than non-lactating mothers, most likely due to the effect of lactation. These mothers were not taking any additional foods during their lactating period. Based on the findings of the study, it is recommended that mothers consume additional energy-rich foods during the first 24 months of lactation to prevent weight loss.
Adolescent↗
Biotin concentrations in maternal plasma and milk during prolonged lactation.
We followed a group of exclusively breast feeding mothers for 12 months after delivery. They numbered 200 at delivery, 140 at 4 months of lactation, 116 at 6, 36 at 9 and 7 at 12 months. The milk concentration of biotin was very low at delivery and subsequently the (geometric) mean value remained at around 4.5 micrograms/l. The mean plasma value was 250 ng/l at delivery and stable (around 330 ng/l) throughout the lactation. There were large intra- and interindividual variations in the concentrations in both milk (from 0 to 27 micrograms/l) and plasma (from 142 to 1090 ng/l). The variations in the milk concentrations result in a similar variation in the biotin intake of the exclusively breast-fed infants. The current recommendations for biotin intake were not met by any of those infants but no manifestations of biotin deficiency were recorded.
Biotin↗
Effect of suckling on serum prolactin, luteinizing hormone, follicle-stimulating hormone, and estradiol during prolonged lactation.
Eight nursing subjects had serum prolactin (PRL), luteinizing hormone, follicle-stimulating hormone, and estradiol levels studied during the first six months postpartum. Each subject had serum samples obtained just before the initiation of suckling and during the next 120 minutes. Baseline PRL levels were high at ten days postpartum (90.1 ng/mL), then slowly declined but remained elevated at 180 days postpartum (44.3 ng/mL), with the stimulus of suckling being able to double the baseline PRL value throughout the study period. Mean estradiol levels were low at ten days postpartum (7.2 pg/mL), then gradually rose to a mean level of 47.3 pg/mL at 180 days postpartum; however, in four subjects who were amenorrheic during the study period, the mean estradiol levels remained low (4.25 pg/mL), while baseline PRL levels remained high (63.6 ng/mL).
Amenorrhea↗
[A case-control study on etiology of epithelial ovarian cancer in Shandong Province].
BACKGROUND & OBJECTIVE: Among gynecologic malignant tumors, Ovarian cancer has the second highest incidence and is the leading cause of death. Some factors are related to the genesis of ovarian cancer, but the etiology is still unclear. This study was to explore the risk factors and pathogenesis of ovarian cancer. METHODS: A total of 307 women with epithelial ovarian cancer and 307 matched women with other benign diseases, treated simultaneously in 19 hospitals in Shandong Province, were enrolled. Conditional univariate and multivariate logistic regression models were used to analyze 105 factors. RESULTS: Univariate logistic regression analysis revealed the risk factors for developing ovarian cancer included higher education, higher income, increased years of ovulation, prolonged period of intrauterine device (IUD) placement, high fat, sweet and meat diet, irregular defecation, constipation, occupation contacting harmful substance, depressed, anxious, impatient, or stressed mood, spirit stimulation, and family history of ovarian cancer in first-degree relatives; the protective factors for preventing ovarian cancer included lower education, prolonged menstrual cycle, prolonged interval between marriage and pregnancy, multiple pregnancies, prolonged lactation, prolonged interval between delivery and recovery of menstruation, hysterectomy, high vegetable and fruits diet, and mild temper. Multivariate logistic regression analysis showed that prolonged menstrual cycle, multiple pregnancies, high vegetable and fruits diet, and mild temper were protective factors, while prolonged period of IUD placement, high meat diet, and spirit stimulation were high-risk factors. CONCLUSION: The etiology of ovarian cancer involves interaction of many factors rather than any single factor.
Adolescent↗
Food restriction during lactation results in prolonged hyposensitivity to the positive-feedback effects of oestradiol.
Food restriction prolongs lactational infertility in rats. Here, we investigated whether an attenuated response to the positive-feedback effects of oestrogen on luteinizing hormone release contributed to this effect. The ability of oestrogen to induce surges in luteinizing hormone in ad libitum fed and food-restricted dams at different times of lactation was compared. The results showed that, on day 20 postpartum, ad libitum fed dams showed luteinizing hormone surges after oestrogen treatment, but food-restricted dams did not. Ovariectomy or RU486 treatment restored the ability of oestrogen to induce luteinizing hormone surges in food-restricted dams, and chronic progesterone exposure reduced oestrogen-induced surges of luteinizing hormone in ad libitum fed ovariectomized dams. Food restriction also resulted in a reduced ability of oestrogen to induce progesterone receptor immunoreactivity, but did not reduce the number of oestrogen receptors (ERalpha) in the anteroventralperiventricular area. As with the surge in luteinizing hormone, the effects of food restriction on oestrogen induction of progesterone receptors were mediated by progesterone. Together, these results suggest that the ability of food restriction to extend the length of lactational diestrus is mediated, in part, by a decrease in sensitivity to the positive-feedback effects of oestrogen. This results from high circulating concentrations of progesterone which apparently reduce the ability of oestrogen to induce progesterone receptor expression.
Animals↗
Comparison of prolonged exercise tests at the individual anaerobic threshold and the fixed anaerobic threshold of 4 mmol.l(-1) lactate.
Prolonged physical exercise tests (50 min) at the threshold of 4 mmol . l-1 lactate (ATc) and at the individual anaerobic threshold (IAT) were applied in 19 rowing athletes. In each of the rowers (n = 19) work loads corresponding to the IAT did not result in a gradual lactase accumulation or exhaustion within 50 min of exercise. Means of lactate concentration and heart rate at the end of exercise were 4.0 +/- 1.6 mmol . l-1 and 182 +/- 13.0 beats . min-1, respectively. In 15 of 19 rowers, the IAT corresponded to lower work loads than the ATc. In these cases, prolonged exercise tests at the ATc showed gradual increases in lactate concentrations to a mean of 9.6 +/- 1.2 mmol . l-1, associated with exhaustion at a mean working time of 14.4 +/- 6.3 min and a mean heart rate of 192 +/- 10.4 beats . min-1. In four rowers, the IAT was found at identical (n = 3) or higher (n = 1) work loads than the ATc. In these cases, after an initial increase no further rise in lactate concentrations in blood was observed, and exhaustion did not occur during the prolonged exercise tests. These findings support the conclusion derived from the lactate kinetics model that the IAT defines the work load at the maximal lactate steady state.
Adolescent↗
The contribution of changes in milk delivery to the prolongation of lactational infertility induced by food restriction or increased litter size.
In rats, the length of lactational anovulation is prolonged when litter size is increased or when the dam is food restricted. In both of these situations the energetic demand on the dam is increased, milk delivery to each pup is reduced, and consequently, patterns of pup suckling may be changed. We investigated the contribution of these factors to the maintenance of lactational anovulation by examining the effect of eliminating milk delivery on the length of lactational diestrus in food restricted and ad lib-fed females nursing litters of 8 pups and in females nursing large (14 pups) and small (6 pups) litters. The results of these studies show that preventing milk delivery neither extends the period of lactational infertility in ad lib-fed females nursing eight pups nor eliminates the effects of increasing litter size on this period.
Animals↗
Serum cholesterol and lipoprotein concentrations in mothers during and after prolonged exclusive lactation.
The effect of exclusive lactation on lipid levels was investigated by evaluating serum concentrations of total and lipoprotein cholesterol, triglyceride (TG), and apoprotein (apo) B in mothers during and after exclusive, prolonged lactation. Serum total cholesterol concentrations were measured at delivery (n = 195), at 2 (n = 165), 6 (n = 119), 9 (n = 74), and 12 months (n = 32) of lactation, and 2 months (n = 27) after ending this exclusive lactation. In a subgroup of 34 mothers, serum levels of very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL), high-density lipoprotein 2 (HDL2), HDL3, and LDL apo B were determined at 2, 6, 9, and 12 months of lactation. The mean value of serum total cholesterol concentrations decreased from 6.2 +/- 0.12 (SEM; n = 195) at delivery to 4.8 +/- 0.1 mmol/L (n = 116) at 6 months of exclusive lactation (P < .001). The average decrement in total cholesterol level was 0.80 mmol/L (P < .001) from delivery to 2 months of lactation and 0.55 mmol/L (P < .001) from 2 to 6 months of lactation, and levels were stable thereafter. In the 27 mothers who were exclusively breast-feeding their infants at 9 months of lactation and whose serum cholesterol levels were measured 2 months after the end of lactation, cholesterol levels increased rapidly to 5.7 +/- 0.21 mmol/L (P = .001). In the subgroup of 34 mothers who were examined more closely, the course just described was also true for serum TG, LDL and VLDL cholesterol, and LDL apo B levels.(ABSTRACT TRUNCATED AT 250 WORDS)
Apolipoproteins B↗
Oestradiol negative feedback inhibition on LH secretion during lactation is prolonged in adolescent primiparous rhesus monkeys.
Lactational infertility in rhesus monkeys is significantly prolonged in adolescent primiparous compared with adult multiparous mothers. In order to determine if this longer period of infertility for young mothers is the result of a greater sensitivity to nursing-induced inhibition of LH release either by enhanced oestradiol negative feedback or a direct non-gonadally mediated suppression, the effects of periodic administration of oestradiol on serum LH concentrations in nursing ovariectomized adolescent primiparous (Prp; n = 5) and adult multiparous (Mlt; n = 7) mothers was assessed. Females were treated every 5-6 weeks with a 21-day time-release capsule of oestradiol which produced serum concentrations of approximately 250, 90 and 45 pmol/l by +6, +13 and +20 days after treatment. Thus, the design permitted assessment of LH and prolactin concentrations under a regime of 21 days of decreasing oestradiol levels followed by 2-3 weeks of no oestradiol treatment. Females were studied from week 3 to week 42 post partum and oestradiol treatment occurred during weeks 5, 11, 21, 26, 31, 36 and 41. Behavioural observations indicated that the amount of time mothers nursed their offspring decreased in a similar fashion throughout the lactational period for both Prp and Mlt females. LH concentrations under the 'no oestradiol' conditions progressively increased throughout lactation reaching maximum levels by week 36 post partum in a similar manner for both Prp and Mlt mothers. These data suggest that differences in fertility between adolescent and adult nursing mothers observed previously cannot be attributed to a difference in a direct non-gonadally-mediated affect on LH. With respect to oestradiol negative feedback inhibition of LH, oestradiol treatment effectively suppressed serum LH concentrations at all points during lactation up to week 31, at which time LH concentrations were maximally suppressed in both Prp and Mlt mothers at +6 days after treatment but by day +13 LH values were significantly higher in Mlt females. After oestradiol treatment during week 36, LH values were again maximally suppressed on day +6 in Prp females but not in Mlt females. However, the response of serum LH after oestradiol treatment during week 41 was similar between Prp and Mlt females at all sampling points.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Impact of follicular aspiration on folliculogenesis as influenced by dietary energy and stage of lactation.
Prolonged dietary energy restriction has been shown to influence the secretion of ovarian hormones and follicular development. Energy balance affects the ability of the cow to support a functional reproductive system during early lactation. Follicular aspiration is a tool that can be used to assess the impact of dietary energy and stage of lactation on follicle development in dairy cattle. Follicular aspiration was conducted twice weekly from d 30 to 100 postpartum in cows fed either 104 or 80% of NRC energy requirements. Oocyte numbers recovered increased linearly from d 30 to 100 postpartum. Cows on high energy diets produced more high quality oocytes, but also produced more poor quality oocytes than cows fed the lower energy diet. Follicles < 5 mm predominated throughout. Cows in early (d 28) and mid (d 117) lactation were used to assess stage of lactation effects on serum and follicular fluid hormones, and quality of oocytes recovered by follicular aspiration procedures for 10 wk. Serum IGF-1 decreased in early lactation cows, but increased in midlactation cows. Follicular fluid progesterone in early lactation cows decreased from 275 to 235 ng/ml, whereas in midlactation cows it increased from 65 to 550 ng/ml at aspiration wk 10. The percentage of high quality ova was higher in early lactation cows (11%) than midlactation cows (6%), but fell to 1% by aspiration wk 7 and increased to 10% by wk 10, whereas percentage of high quality ova in midlactation cows steadily declined to 2% by wk 10. Milk yield and energy balance affect patterns of folliculogenesis in lactating dairy cows.
Animals↗
Nutritional aspects of human lactation.
This paper reviews the literature on the incidence and duration of breast-feeding in various countries, the volume and composition of breast milk, the health and nutrition of breast-fed babies as judged by growth and morbidity, maternal nutritional requirements during lactation, and the effect of prolonged lactation on maternal health. It appears that lactation can be as well sustained by impoverished as by affluent mothers, and that even in communities where malnutrition is common the average growth of infants is satisfactory up to the age of about 3 months on a diet of breast milk alone. Breast milk appears to have specific anti-infective properties, but prolonged breast-feeding will not prevent infections among older infants reared in a poor environment. The authors believe that breast-feeding is the best form of nutrition for the young infant and deplore its decline in modern industrial societies. The recommendations of various FAO/WHO Expert Groups on nutritional intakes during lactation are summarized. The need for an increased daily energy intake of 4.2 MJ (1 000 kcal) is questioned, and an increase of 2.5 MJ (600 kcal) is suggested. Data on the effect of prolonged lactation on the health of the mother are scanty; body weight appears to be maintained even among poorly nourished mothers. The authors stress the need for well-planned and technically adequate studies of the material and psychological factors involved in breast feeding.
Breast Feeding↗
Rat blood and muscle lactate after prolonged exercise.
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Animals↗
Hormonal adaptation to the stresses imposed upon sodium balance by pregnancy and lactation in the Yanomama Indians, a culture without salt.
The Yanomama Indians of northern Brazil and southern Venezuela have been identified as a "no-salt" culture. In this study, data were obtained to determine in this population the adjustments of sodium-related hormones to the stresses imposed upon sodium balance by pregnancy and prolonged lactation. Controls against the possibility that findings in the Yanomama were ethnic rather than dietary were provided by similar observations in the Guaymi Indians of Panama, who have free access to salt. Urinary concentrations of sodium were approximately 1 mEq/l in male and female Yanomama, with 24-hour excretion rates in the males averaging 1 mEq, similar to our prior observation. The pregnant Yanomama had exceeding high urinary concentrations of aldosterone. These were associated with higher plasma renin activities and serum aldosterone concentrations than in all other subjects. Although pregnant Guaymi had elevations of serum and urinary aldosterone, these were significantly lower (p < 0.001) than those of the Yanomama. Prolonged lactation in the Yanomama was associated with elevation of plasma renin activity and serum and urinary aldosterone concentration compared with the Guaymi, but were not higher than those in nonlactating Yanomama females. The findings suggest that pregnancy in a salt-poor environment is associated with an exaggerated augmentation of hormonal responses that enhance positive sodium balance.
Adult↗
Prolonged breast-feeding and mortality up to two years post-partum among HIV-positive women in Zambia.
BACKGROUND: A previously reported association between prolonged lactation and maternal mortality has generated concern that breast-feeding may be detrimental for HIV-positive women. METHODS: As part of a trial conducted in Lusaka, Zambia, 653 HIV-positive women were randomly assigned either to a counseling program that encouraged abrupt cessation of breast-feeding at 4 months (group A) or to a program that encouraged prolonged breast-feeding for the duration of the woman's own informed choice (group B). We examined whether mortality up to 2 years post-partum increased with breast-feeding for a longer duration. RESULTS: There was no difference in mortality 12 months after delivery between 326 HIV-positive women randomly assigned to short breast-feeding [group A: 4.93%; 95% confidence interval (CI), 2.42-7.46] versus 327 women assigned to long breast-feeding (group B: 4.89%; 95% CI, 2.38-7.40). Analysis based on actual practice, rather than random assignment, also demonstrated no increased mortality due to breast-feeding. CONCLUSIONS: Although HIV-related mortality was high in this cohort of untreated HIV-positive women, prolonged lactation was not associated with increased mortality.
Adult↗