Effectiveness of lactational amenorrhoea in prevention of pregnancy in Manila,the Philippines: non-comparative prospective trail.

OBJECTIVE: To determine the contraceptive efficacy of the lactational amenorrhoea method. DESIGN: Non-comparative prospective trial. SETTING: Urban Manila, the Philippines. SUBJECTS: 485 lower income, educated women with extensive experience of breast feeding. INTERVENTION: Women were offered all available contraceptives for use after birth. Those who chose the lactational amenorrhoea method were taught the method, screened for the study, and followed for 12 months to determine the risk of pregnancy when the method was used. MAIN OUTCOME MEASURES: Life table pregnancy rates during correct and incorrect use of the method, censored monthly in the event of sexual abstinence or the use of another contraceptive method. RESULTS: The lactational amenorrhoea method was 99% effective when used correctly (that is, during lactational amenorrhoea and full or nearly full breast feeding for up to six months). At 12 months the effectiveness during amenorrhoea dropped to 97%. CONCLUSIONS: The lactational amenorrhoea method provided as much protection from pregnancy as non-breast feeding women experience with non-medicated intrauterine devices and barrier methods. The contraceptive effect of lactation cannot be attributed to lactational or postpartum abstinence.     

The duration of lactational amenorrhoea in urban Bangladeshi women

The duration of lactational amenorrhoea, and infant feeding patterns and behaviour, were investigated in a sample of 97 mother-infant pairs living in a poor urban area of Dhaka, Bangladesh. A seven-hour time allocation method was used to determine the number of breast-feeding bouts and their duration. The seven-hour observation period was conducted on five occasions: at birth, 1 month, 4 months, 8 months and either 10 or 11 months. The median duration of lactational amenorrhoea was determined to be 24.07 weeks using survival analysis. Mothers who breast-fed their babies for longer and more frequently had, on average, a longer period of lactational amenorrhoea. There was no relationship between sociodemographic characteristics of the mother and duration of lactational amenorrhoea, nor was there any significant relationship between maternal anthropometry and birth weight of the baby and duration of lactational amenorrhoea, but there was a tendency for women with lower body mass index to have longer durations. Using the Cox proportional hazards model, the best predictor of duration of lactational amenorrhoea was the mean of months 0 and 1 durations of breast-feeding, adjusted for the mean frequencies for those months. The introduction of weaning food was also an important predictor.     

Extending lactational amenorrhoea in Manila: a successful breast-feeding education programme.

An experimental breast-feeding education programme conducted at the Philippine General Hospital in Manila demonstrated that women could be motivated to improve their breast-feeding practices and lengthen their period of lactational amenorrhoea in comparison to a control group. Mothers who participated in the programme breast-fed their babies more frequently, delayed the introduction of regular supplements, used fewer bottles and pacifiers and maintained night feeding longer than mothers who were not exposed to the positive breast-feeding messages. The programme was successful in lengthening the period of amenorrhoea among women with elementary, high school, or technical school education, but not among college-educated women. Different educational approaches may be necessary for women of different education levels.     

Lactational amenorrhoea in well-nourished Toba women of Formosa, Argentina

The proximate causes of the contraceptive effect of lactation are still a matter of productive debate. This study sought to disentangle the relative impact that intense breast-feeding practices and maternal nutrition have on the regulation of ovarian function in nursing women. A mixed-longitudinal, direct-observational, prospective study was conducted of the return to postpartum fecundity in 113 breast-feeding, well-nourished Toba women. A sub-sample of 70 women provided data on nursing behaviour, daily activities, diet quality and urinary levels of oestrone and progesterone metabolites. Well-nourished, intensively breast-feeding Toba women experienced a relatively short period of lactational amenorrhoea (10.2 +/- 4.3 months) and a high lifetime fertility (TFR=6.7 live births/woman). Duration of lactational amenorrhoea was not correlated with any of the nursing parameters under study or with static measures of maternal nutritional status. The results indicated that the pattern of resumption of postpartum fertility could be explained, at least partly, by differences in individual metabolic budgets. Toba women resumed postpartum ovulation after a period of sustained positive energy balance. As the relative metabolic load hypothesis suggests, the variable effect of lactation on postpartum fertility may not depend on the intensity of nursing per se but rather on the energetic stress that lactation represents for the individual mother.     

Variability of breast sucking, associated milk transfer and the duration of lactational amenorrhoea.

Quantitative relationships between physical parameters of sucking, milk transfer and the duration of amenorrhoea were examined in normal mother-baby pairs under exclusive breastfeeding. Sucking pressures were recorded twice on the second and once on the fifth month after birth, during complete breastfeeding episodes, by means of a catheter attached to the nipple and connected to a pressure transducer, the signals of which were analysed by computer. Babies were weighed before and after each sucking episode to estimate milk transfer. In the first nursing episode after noon, 2-month-old babies sucked from 140 to > 800 times during 4-15 min from the first breast, obtaining from 20 to > 100 g milk. The physical parameters of sucking and milk transfer exhibited high inter-individual but low intra-individual variabilities. There were significant differences in the physical parameters of sucking and milk transfer efficiency between first and second breast and between the second and fifth months after birth. Milk transfer efficiency was inversely correlated with time occupied by non-sucking pauses > or = 1.5 s, and was directly correlated with mean intersuck intervals in the first breast and with duration of the sucking episode, number of sucks, mean pressure and area under the pressure curve in the second breast. There was no correlation between the physical parameters of sucking and duration of lactational amenorrhoea (n = 62). However, significantly more mothers had amenorrhoea lasting > 180 days among those whose babies spent a longer proportion of the nursing episode in non-sucking pauses > or = 1.5 s. This finding indicates that sensory stimulation of the nipple produced during a nursing episode by stimuli other than sucking itself may have an important role in sustaining lactational amenorrhoea. It is concluded that nursing episodes have a complex structure that allows the development of a breastfeeding phenotype in each mother-baby pair, exhibiting important inter-individual variability. The present analysis does not support the contention that this source of variability accounts for the variability in the duration of lactational amenorrhoea.     

Postpartum lactational amenorrhoea as a means of family planning in the Sudan: a study of 500 cases

The lactational histories of 500 Sudanese women were studied retrospectively to examine postpartum lactational amenorrhea as a method of family planning. Particular attention was given to the factors affecting postpartum lactational amenorrhea, including supplementary feeding and the use of modern contraceptive methods. Breast-feeding was overwhelmingly practised (90%) among this sample, which was roughly representative of the Sudanese population as a whole. The prevalence of amenorrhea among this group of lactating women was quite high (73%). Duration of lactational amenorrhea ranged from 2 to 36 months with a median of 12 months. Introduction of supplementary feeding had little effect on lactational amenorrhea up to the 9th month of breastfeeding. Beyond the 12th month of breastfeeding, lactational amenorrhea was significantly prolonged by postponing the introduction of supplementary feeding until the 4th month or later. Ovulation, and hence conception, during lactational amenorrhea was unpredictable. It occurred as early as the 3rd or as late as the 36th month postpartum. Conceptions interrupting lactational amenorrhea soon after delivery (3-9 months) were more frequent among primiparous women. The failure rate of lactational amenorrhea as a contraceptive was 8.4%. Though extremely high compared to that of the pill, lactational amenorrhea was more useful as a fertility control mechanism because, in this study, a high proportion of women initiated pill use, but soon discontinued it because of side effects. Modern contraceptive practice was not prevalent. Amenorrheic mothers accepted the pill after the 6th month postpartum (41%, compared to lactating mothers whose menses had returned who started much earlier. 49% of the women studied relied completely on the protection of lactational amenorrhea. 57% of all lactating women who used the combined pill reported a reduction in milk production. Knowledge of modern contraception was poor and incorrect in many cases, leading to several policy implications, including usage of sterilization.     

Determinants of breast-feeding and post-partum amenorrhoea in Orissa

A life table analysis is made of the duration of breast-feeding and post-partum amenorrhoea in Orissa, India, taking one variable at a time using data from a baseline survey of fertility and mortality (BSFM) conducted on the lines of the World Fertility Survey. Then a multivariate (proportional hazard) analysis showed that socioeconomic factors including residence, caste status and education influence the breast-feeding and post-partum amenorrhoea periods. There was no effect of maternal age on the length of breast-feeding, but mean length of post-partum amenorrhoea varied with age. The durations of breast-feeding and post-partum amenorrhoea are strongly related.     

When ancient meets modern: the relationship between postpartum non-susceptibility and contraception in sub-Saharan Africa

Extended durations of postpartum non-susceptibility (PPNS) comprising lactational amenorrhoea and associated taboos on sex have been a central component of traditional reproductive regimes in sub-Saharan Africa. In situations of rising contraceptive prevalence this paper draws on data from the Demographic Health Surveys to consider the neglected interface between ancient and modern methods of regulation. The analysis reports striking contrasts between countries. At one extreme a woman's natural susceptibility status appears to have little bearing on the decision to use contraception in Zimbabwe, with widespread 'double-protection'. By contrast, contraceptive use in Kenya and Ghana builds directly onto underlying patterns of PPNS. Possible explanations for the differences and the implications for theory and policy are discussed.     

Primary amenorrhoea: the ambiguous non-entity.

Hypothalamic-pituitary activity was investigated in 20 women with primary amenorrhoea, in whom gonadal dysgenesis and lower Müllerian duct anomalies had been excluded. There was no specific or uniform pattern of response to luteinising hormone-releasing hormone and no evidence of a common defect at pituitary-hypothalamic level to account for the absence of spontaneous menstruation. Six women had hyperprolactinaemia; of these five had radiological evidence of pituitary enlargement. The conventional distinction between "primary" and "secondary" amenorrhoea should be abandoned, and, in common with current practice for other endocrine glands, primary amenorrhoea should indicate an abnormality of the gonad itself and secondary amenorrhoea an abnormality that results from hypothalamic-pituitary dysfunction.     

Postpartum amenorrhoea in Ethiopia: The role of weaning,child death,and socioeconomic factors

Abstract

Using data from the 1990 National Family and Fertility Survey (NFFS) and employing discrete‐time hazards models, we examine the effect of weaning, child death, and socioeconomic factors on postpartum amenorrhoea in Ethiopia. The results show that 91 in every 100 mothers breastfed their child for at least 6 months. The median duration of breastfeeding stands at 18 months, and amenorrhoea lasts for a median duration of 12 months. Significant variations in breastfeeding and amenorrhoea duration are also observed among the different categories of breastfeeding women. The median duration of breastfeeding for lactating women is 24 months, 6 months for those who weaned, and 2 months for those whose child died. The median duration of postpartum amenorrhoea is 14 months for breastfeeding women, 12 months for those who weaned, and 6 months for those whose child died. Discrete‐time hazard models reveal that child death has the strongest effect on the resumption of menses. Net of other factors, the risk of returning to menses increased 3 times for mothers whose child died. The effect of child death, however, decreases over time. Weaning also has a significant positive effect; and, like child death, its effect diminishes as time passes. The study further shows significant differences in the risk of returning to postpartum menses by socioeconomic characteristics of the women, even though they are breastfeeding.     

Analysis of postpartum lactational amenorrhoea in relation to breast-feeding: some methodological and practical aspects.

A large multicentre epidemiological study was carried out by WHO between 1991 and 1995 to analyse the duration of lactational amenorrhoea in relation to breast-feeding. The main results of this analysis, which used classical statistical modelling, have been already published. However, some specific aspects of the postpartum fertility amenorrhoea and breast-feeding covariates, and more specifically the observed progressive exhaustion of the breast-feeding inhibitory effect on the reproductive axis, may justify a closer look at the validity of the statistical tools. Indeed, as has already been emphasized, analysis of large longitudinal data sets in reproduction often faces three difficulties: (i) the precise determination of the event of interest, (ii) the way to handle the time evolution of both the studied variables and their effect on the event of interest and (iii) the often discrete nature of the data and the associated problem of tied events. The first objective of the present work was to give additional insights into the estimation and quantification of the dynamics of the effect of breast-feeding over time, considering this covariate either as fixed or time-dependent. The second objective was to show how to perform the analyses using corresponding adapted procedures in widely available statistical packages, without the need for acquiring particular programming skills.     

Post-"pill" amenorrhoea--cause or coincidence?

The relationship of contraceptive history to diagnostic category of amenorrhoea was analysed in 131 consecutively investigated cases of secondary amenorrhoea. Amenorrhoea occurred in 52 patients immediately after discontinuing the oral contraceptive. Twenty-two had had amenorrhoea before oral contraceptive treatment and 23 patients before the episode of non-contraceptive-related amenorrhoea investigated here. When these cases were excluded from analysis there was no significant difference in the distribution of any of the diagnostic categories between those who had used the oral contraceptive and those who had not. The results suggest that using oral contraceptives does not cause subsequent amenorrhoea.     

Amenorrhoea after Discontinuing Combined Oestrogen-Progestogen Oral Contraceptives

Out of 210 women seen at the Middlesex Hospital with secondary amenorrhoea the 63 who developed it after stopping oral contraceptives were fully investigated. Five had organic disease sufficient to account for the amenorrhoea (one had severe diabetes, one a pituitary tumour, and three premature ovarian failure); two patients had galactorrhoea (one of whom also had the pituitary tumour); two had anorexia nervosa.Of the 63 women 40 (63%) had suffered from amenorrhoea or prolonged or irregular menstrual cycles before taking the pill, and this suggested that combined oestrogen-progestogen oral contraceptives should be used with caution for women with irregular menstruation.Nineteen patients wished to become pregnant and 12 have so far done so after treatment with clomiphene or gonadotrophins.In another study 204 women recorded when their first menstrual cycle occurred after stopping the pill. Seventy-four had a cycle longer than five weeks but only five exceeded three months, and only one of the five had more than six months'' amenorrhoea. These results confirm that the incidence of amenorrhoea after stopping oral contraceptives is low.     

Chronic neuropeptide Y infusion during lactation suppresses pup growth and reduces the length of lactational infertility in rats

In lactating rats, food restriction potentiates the already high levels of hypothalamic neuropeptide Y (NPY). To investigate the role that high levels of NPY might play in the prolongation of lactational infertility that typically accompanies a food restricted lactation we investigated the effects of chronic central infusions of NPY in ad libitum-fed lactating females. First, we compared the effects of intracerebroventricular (icv) infusion of NPY from Days 12-19 postpartum at a dose of 14.4 microg/day with a similar treatment in nonlactating females. In subsequent experiments we examined the effects of NPY infusions into the lateral ventricle at doses of 6 or 20 mug/day or unilaterally into the medial preoptic area at a dose of 1 microg/day from either Days 12-19 or 7-21 postpartum. Effects on food intake; female body weight; and, where appropriate, litter weight and length of lactational diestrus were compared between NPY and vehicle-treated females. As expected NPY infusion produced a robust increase in body weight and food intake in nonlactating females that was accompanied by a suppression of cyclicity. By contrast NPY treatment in lactating rats resulted in a marked decrease in litter growth and an earlier termination of lactational diestrus.     

Bone mineral loss in young women with amenorrhoea.

OBJECTIVE--To examine the impact of amenorrhoea on bone mineral density in women of reproductive age. DESIGN--Cross sectional study of 200 amenorrhoeic women compared with normally menstruating controls. SETTING--Teaching hospital outpatient clinic specialising in reproductive medicine. SUBJECTS--200 Women aged 16-40 with a past or current history of amenorrhoea from various causes and of a median duration of three years, and a control group of 57 age matched normal volunteers with no history of menstrual disorder. MAIN OUTCOME MEASURE--Bone mineral density in the lumbar spine (L1-L4) as measured by dual energy x ray absorptiometry. RESULTS--The amenorrhoeic group showed a mean reduction in bone mineral density of 15% (95% confidence interval 12% to 18%) as compared with controls (mean bone mineral density 0.89 (SD 0.12) g/cm2 v 1.05 (0.09) g/cm2 in controls). Bone loss was related to the duration of amenorrhoea and the severity of oestrogen deficiency rather than to the underlying diagnosis. Patients with a history of fracture had significantly lower bone density than those without a history of fracture. Ten patients had suffered an apparently atraumatic fracture. CONCLUSIONS--Amenorrhoea in young women should be investigated and treated to prevent bone mineral loss. Menopausal women with a past history of amenorrhoea should be considered to be at high risk of osteoporosis.     

Relationships between fertility, peak milk yields and lactational persistency in dairy cows

Peak milk yield, lactational persistency and conception rates were studied using 5928 lactation records of high milk-producing cows at three California dairies. Log-linear analysis was used to study relationships between peak milk yield, lactational persistency, dairy of origin, lactation number and conception rates in 3850 completed lactations. Cows with peak milk yields greater than the median (38.2 kg milk per day) were less likely to have conceived in one or two breedings than cows with peak milk yields lower than or equal to the median. Cows with a higher than median (0.755) lactational persistency were less likely to have conceived in one or two breedings than cows with a lactational persistency lower than or equal to the median. Dairy of origin had a significant effect on the probability of conceiving in one or two breedings. Cows in the first lactation were more likely than those in subsequent lactations to conceive in one or two breedings. This retrospective study demonstrated that subfertility is associated with high peak lactational yields in high milk-producing California cows.     

The impact of malnutrition on human lactation: observations from community studies

There is very little scope for the direct examination of relationships between nutrient intake and lactational performance in women. Experimental investigations are limited to the effects of dietary supplementation in pregnancy and/or lactation. To obtain comparisons between normal and undernourished women, studies have to be performed at a community level. Studies in Cambridge, The Gambia, and elsewhere indicate that the impact of variations in nutrient intake on lactational performance is limited: over the ranges normally found in developed and developing countries milk output does not vary in relation to energy intake, and effects of nutrient intake on milk quality are restricted to increases in vitamin content after appropriate supplementation.     

Raised serum prolactin levels in amenorrhoea.

Serum prolactin levels measured by specific radio-immunoassay were over 30 mug/l in seven out of 25 women with amenorrhoea and in eight women with the amenorrhoe-galactorrhoea syndrome. There was no apparent relationship between these levels and levels of follicle-stimulating hormone, luteinizing hormones, and thyroid-stimulating hormone. Bromocriptine caused a transient fall in the proclatin levels in six out of seven cases, and in three menstruation and ovulation were restored. Estimation of serum prolactin may become important in assessing the degree of hypothalamic-pituitary dysfunction in amenorrhoea, and it may help in identifying a subgroup of patients at risk of developing a pituitary tumour or patients who may respond to specific treatment.     

Outcome of pregnancy in underweight women after spontaneous and induced ovulation

Low maternal weight before pregnancy and poor weight gain during pregnancy are known to result in an increased prevalence of low birthweight infants. Low body weight is also an important cause of amenorrhoea. The hypothesis that amenorrhoeic underweight women who become pregnant after induction of ovulation are more at risk of delivering low birthweight infants than underweight women who ovulate spontaneously was investigated. Forty one pregnant women in whom ovulation had been induced and 1212 in whom ovulation was spontaneous were studied. Women ovulating spontaneously whose weight was normal and who showed good weight gain during pregnancy (>450 g a week) had the lowest incidence (6%) of babies who were small for gestational age. Underweight women (body mass index <19·1) who ovulated spontaneously had a threefold increased risk of delivering babies who were small for gestational age (18%). Overall, the women in whom ovulation had been induced had an even higher risk of babies who were small for dates (25%), and this risk was greatest (54%) in those who were underweight.The outcome of pregnancy is related to weight before conception, which in many cases reflects nutritional state; lack of spontaneous ovulation indicates an increased risk of producing a small for dates infant. The most suitable treatment for infertility secondary to weight related amenorrhoea is therefore dietary rather than induction of ovulation.     

Pulsatile infusion of gonadotrophin releasing hormone (GnRH): investigative and therapeutic applications

Normal gonadotrophin secretion, and therefore normal ovarian function, depend on delivery to the pituitary of the hypothalamic neuropeptide gonadotrophin releasing hormone (GnRH) in a pulsatile pattern. In the mid-follicular phase of the menstrual cycle, for example, discrete pulses of luteinizing hormone (LH) can be observed at approximately 90 min intervals. Many disorders of ovulation are caused by abnormalities of this natural pulsed signal. We have developed and used a small portable infusion pump to deliver GnRH to women with hypothalamic amenorrhoea; our studies, and those of other groups, have shown that successful ovulation and pregnancy result from such treatment. The results of treatment at St Mary's Hospital show that 16 women with hypogonadotrophic amenorrhoea received a total of 31 cycles of treatment with pulsatile GnRH; 25 (81%) of these cycles were ovulatory and 11 of the 14 women who were trying to conceive became pregnant. There was only one multiple pregnancy (twins).