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PubMed1984

Vitamin C nutrition during prolonged lactation: optimal in infants while marginal in some mothers.

Prolonged breast-feeding is practiced by mothers in the hope of improving their infants' health and preventing diseases. In this study of the nutritional adequacy of breast-feeding, 200 mothers with healthy, full term newborns were encouraged to breast-feed exclusively. At age 6 months 116 infants and at age 9 months 36 infants remained exclusively breast-fed. The control infants were weaned early and they received vitamin C through a supplemented milk formula and solid food. The exclusively breast-fed infants were able to maintain their plasma vitamin C concentration at the same or a higher concentration than the vitamin C-supplemented controls. Their plasma concentration was about 2-fold compared with the maternal concentration. It was relatively independent of maternal nutrition and of vitamin C concentration in milk. The mother's intake of vitamin C influenced their plasma and milk concentrations. About 6% of the mothers had subnormal plasma concentrations without symptoms. The lowest concentrations occurred 2 months postpartum and during the spring. Thus, exclusively breast-fed infants are well protected against vitamin C deficiency, but marginal intake in lactating mothers is more common than assumed for a well-nourished population.

Ascorbic Acid↗
PubMed1993

Maternal weight-loss patterns during prolonged lactation.

Weight and triceps-skinfold thickness were measured until 24 mo postpartum in matched cohorts of women who breast-fed for > or = 12 mo (BF; n = 46) or < or = 3 mo (FF; n = 39). In the BF group, breast-feeding frequency and breast-milk energy output were determined every 3 mo until 18 mo. Weight loss from 1 to 12 mo postpartum was significantly greater in BF than in FF women (4.4 vs 2.4 kg, P < 0.05), due primarily to differences in weight loss from 3 to 6 mo. BF mothers had a net loss in triceps-skinfold thickness whereas FF mothers gained fat at this site (-0.4 vs 2.4 mm, P < 0.05). Breast-feeding frequency and total time breast-feeding were related to weight loss in the BF group from 6 to 12 mo. Maternal weight did not differ significantly between 12 and 24 mo in either group. We conclude that lactation enhances weight loss postpartum if breast-feeding continues for at least 6 mo.

Adult↗
PubMed1993

Breast cancer and prolonged lactation. The WHO Collaborative Study of Neoplasia and Steroid Contraceptives.

The possible relationship between breastfeeding and risk of breast cancer was assessed in multinational hospital-based case-control study that was conducted from 1979 to 1986 in 10 countries, including some in which many women lactated for long periods of time. Data were collected by personal interviews of 2336 cases and 14,900 controls. No statistically significant trends in relative risk estimates with duration of lactation were observed in all women combined, in women who were pre-or postmenopausal, in women of various ages at diagnosis, in women with different numbers of livebirths, or in women characterized by the presence or absence of other risk factors for breast cancer. No trends in risk were observed with mean number of months that a woman lactated per breastfed child, or with number of pregnancies followed by treatment with oral or injectable medication to suppress lactation. In premenopausal women, and in those with two or more livebirths, most risk estimates for women who lactated for various lengths of time > 6 months, relative to the risk in women who breastfed for < or = 3 months, were less than unity, but the 95% confidence intervals of all estimates included one. Long-term lactation may reduce slightly the risk of breast cancer, but the evidence for this from the present and prior investigations is not strong.

Adult↗
PubMed1995

Prolonged lactation and endometrial cancer. WHO Collaborative Study of Neoplasia and Steroid Contraceptives.

BACKGROUND: The risk of endometrial cancer is related to oestrogen levels, showing an increased risk with increasing endogenous or exogenous oestrogen stimulation and a reduced risk when oestrogen is opposed by progesterone. During breastfeeding, the reduction of endogenous oestrogen exposure is larger than that of progesterone, suggesting that breastfeeding may possibly reduce the risk of endometrial cancer. METHODS: The relationship between lactation and endometrial cancer was assessed in data from six countries, including four developing countries, that were collected for a multinational hospital-based case-control study conducted between 1979 and 1988. In all, 136 cases were compared with 933 controls matched on age, hospital, and year of interview. Standardized questionnaires, administered in the local language, ascertained information on the length of time breastfed, age started and stopped breastfeeding, reproductive and contraceptive practices, and other risk factors for endometrial cancer. Conditional logistic regression was used to control for the confounding effects of gravidity and age at menarche. RESULTS: Significant decreasing trends in risk were observed with increasing duration of lactation, and with months of breastfeeding per pregnancy. Risk was lowest in women who had most recently lactated, and the apparent protective effect declined with time since cessation of breastfeeding, so that there was no evidence for a protective effect after age 55 even in women who had breastfed for over 5 years. CONCLUSIONS: The long-term lactation that takes place in developing countries probably reduces the risk of endometrial cancer, but this effect may not persist into the ages at which this disease is most common.

Adolescent↗
PubMed1992

Prolonged lactation contributes to depletion of maternal energy reserves in Filipino women.

This paper identifies determinants of women's postpartum weight and weight change in a large group of Filipino women followed for 24 mo. Longitudinal, multivariate models focused on the effects of lactation, while controlling for energy intake, energy expenditure, reproductive history and seasonality. Lactation was found to have a significant negative effect on weight of urban women. The negative effects of lactation increased with the intensity and duration of breast-feeding. Among rural women negative effects of lactation on weight were observed only after 10-14 mo. Models of net postpartum weight change (from 2 to 24 mo) among nonpregnant women confirmed an important role for lactation. The likelihood of weight loss was significantly increased by lactation of more than 12-mo duration, by greater maternal age and by low dietary energy intake. The effects of lactation on maternal energy reserves can be mitigated substantially be increasing maternal dietary energy intakes.

Energy Intake↗
PubMed1980

Hyperprolactinaemia during prolonged lactation: evidence for anovulatory cycles and inadequate corpus luteum.

Serum progesterone and prolactin were measured in single blood samples collected from 176 mothers during a lactation period of 2 years and from fifty-six non-lactating, non-pregnant and regularly menstruating women from the Kivu region (Zaïre). On the basis of serum progesterone levels, evidence of corpus luteum activity was obtained in 61% of non-lactating women; but only 20% of non-amenorrhoeic lactating mothers. This suggests an increased incidence of anovulatory cycles and/or cycles with short luteal phases among nursing mothers. The incidence of corpus luteum activity was 8% in amenorrhoeic lactating mothers. In this 8% recurrence of ovulation preceded return of menstruation. Mean serum progesterone was significantly higher and serum prolactin significantly lower in the non-lactating women than in the nursing mothers. This suggests that although ovulation occurs, corpus luteum activity is inadequate in hyperprolactinaemic nursing mothers.

Anovulation↗
PubMed1986

Nursing behaviour, prolactin and postpartum amenorrhoea during prolonged lactation in American and !Kung mothers.

In order to determine the effects of protracted nursing in American women, blood was collected hourly for 24 h and nursing periods recorded in 20 mothers, 10 amenorrhoeic, 3 3/4 to 17 1/4 months postpartum (PP), and 10 menstruating, 5 1/4 to 46 months PP. These data were compared to the daytime nursing behaviour and 1000-1100 h PRL of women among !Kung hunter-gatherers of Botswana, a non-contraceptive using population with a birth space interval of greater than 3 years. Intense nursing behaviour maintained amenorrhoea and hyperprolactinaemia for 1 to nearly 2 years PP in both American and !Kung mothers. Among Americans, 80 min of nursing per day, in conjunction with a minimum of six nursing episodes, was highly predictive of remaining amenorrhoeic up to 18 months PP. Amenorrhoea was always accompanied by hyperprolactinaemia, but delay in the onset of menses was related more to nursing behaviour than to a particular 24 h PRL level. The 1000-1100 h sample is equivalent to and about half of the 24 h mean in high and low intensity nursers, respectively. The !Kung women were similar to the high intensity nursing American women in 1000-1100 h PRL, percent amenorrhoeic, and the number of minutes of daytime nursing.

Adult↗