Fertility after childbirth: infant feeding patterns, basal PRL levels and post-partum ovulation

Reproductive Women’s Knowledge on Possibility of Pregnancy after Birth but before Resumption of Menstruation and Its Associated Factors in Ethiopia: A Population-Based Study Using the 2016 Ethiopian Demographic Health Survey

Introduction

Worldwide, specifically in developing countries, women believe that a woman cannot become pregnant unless she sees her first postpartum menstruation. Due to this knowledge gap, most women did not use any contraceptives till their 1^st postpartum menstruation. Hence, about 44% of women were susceptible to unintended pregnancy in the postpartum period. Assessing women knowledge on possibility of pregnancy after giving birth but before returning of menses and its associated factors will help to increase women's recognition on the issue and for early commencement of appropriate postpartum family planning methods to reduce burden of unintended pregnancy.

Objective

To assess the level of knowledge on possibility of pregnancy after giving birth but before returning of menses and its associated factors among reproductive women in Ethiopia.

Methods

A secondary data analysis using the 2016 Ethiopian Demographic Health Survey was employed. Samples were selected using two-stage stratified sampling technique. Descriptive statistics and logistic regressions were used. Adjusted odds ratio (AOR) with 95% confidence interval was used to interpret associations, and a significant association was declared at a p value of <0.05.

Result

A total of 15,683 reproductive women aged from 15 to 49 years were included. Of them, about 53% did not know that a woman can get pregnant after giving birth but before resumption of her menstruation. Age being 35 years and above (AOR = 1.50; 95%CI = 1.34, 1.67), educational status of secondary and above (AOR = 1.18; 95%CI = 1.06, 1.32), being ever married (AOR = 1.67; 95%CI = 1.47, 1.89), knowledge of any family planning method (AOR = 1.81; 95%CI = 1.52, 2.16), getting counseling on family planning methods (AOR = 1.41; 95%CI = 1.28, 1.55), and being knowledgeable on their ovulatory cycle (AOR = 1.68; 95%CI = 1.55, 1.82) were found to be significantly associated with being knowledgeable on the issue.

Conclusion

Reproductive women's level of knowledge on the possibility of pregnancy after giving birth but before returning of menses was low. Factors associated with being knowledgeable on the issue were identified. Therefore, strategies should be developed to increase their level of knowledge for reducing unintended pregnancy and its complications by integrating family planning counseling with infant immunization services.

Association Between Breastfeeding and Postpartum Multiple Sclerosis Relapses: A Systematic Review and Meta-analysis

Importance

Multiple sclerosis (MS) relapses may be increased in the postpartum period, and whether breastfeeding is associated with reduction in the risk of postpartum relapses remains controversial.

Objective

To perform a systematic review and meta-analysis to evaluate whether breastfeeding is associated with reduction in postpartum MS relapses compared with not breastfeeding.

Data Sources

PubMed and Embase were searched for studies assessing the association between breastfeeding and MS disease activity published between January 1, 1980, and July 11, 2018, as well as reference lists of selected articles.

Study Selection

All study designs assessing the association between breastfeeding and postpartum relapses in MS relative to a comparator group were included.

Data Extraction and Synthesis

Study eligibility assessment and extraction of study characteristics, methods, and outcomes, were performed independently by 2 reviewers following PRISMA guidelines. Risk of bias was evaluated by 2 independent reviewers with the ROBINS-I tool for nonrandomized, interventional studies. Findings from studies with data available for the number of women with postpartum relapses in the breastfeeding and nonbreastfeeding groups were combined with a random-effects model.

Main Outcomes and Measures

Postpartum MS relapse.

Results

The search identified 462 unique citations, and 24 (2974 women) satisfied eligibility criteria and were included, of which 16 were included in the quantitative meta-analysis. The pooled summary odds ratio for the association of breastfeeding with postpartum relapses was 0.63 (95% CI, 0.45-0.88; P = .006) compared with a reference of nonbreastfeeding. Pooled adjusted hazard ratio across 4 studies that reported this finding was 0.57 (95% CI, 0.38-0.85; P = .006). There was moderate heterogeneity (I2 = 48%), which was explained by variable prepregnancy relapse rate, postpartum follow-up duration, and the publication year. A stronger association was seen in studies of exclusive rather than nonexclusive breastfeeding, although both demonstrated an association. Studies were rated at moderate and serious risk of bias, with concern for residual confounding, although sensitivity analysis including only moderate quality studies was consistent with a protective outcome of breastfeeding.

Conclusions and Relevance

These findings suggest that breastfeeding is protective against postpartum relapses in MS, although high-quality prospective studies to date are limited and well-designed observational studies that aim to emulate a randomized trial would be of benefit.

Change in pregnancy-associated multiple sclerosis relapse rates over time: a meta-analysis

BACKGROUND

Women with MS are advised that relapse rates fall during pregnancy and rebound post-partum. This advice originates from 1998; smaller, more recent, studies have not been previously pooled.

METHODS

All studies published since 1998 providing raw relapse data were considered for inclusion. Single arm meta-analysis was performed using a restricted maximum likelihood random effects model with inverse variance; secondary subgroup analysis and meta regression were then performed. Annualised relapse rates (ARR), or relapse numbers/rates suitable for conversion into ARR during pregnancy and the post-partum period were included. Secondary subgroup analysis examined year of data collection, DMT exposure, breastfeeding and data source.

RESULTS

7034 pregnancies from 6430 women were included. ARR fell from 0.57 (95%CI 0.45-0.70) pre-pregnancy to 0.36 (0.28-0.44), 0.29 (0.21-0.36) and 0.16 (0.11-0.21) during trimesters 1,2, and 3, with a post-partum rebound (ARR 0.85, 95%CI 0.70-1.00). ARR reduced pre-pregnancy and post-partum over time (p<0.001). Relapse rates were lower in claims databases than elsewhere.

CONCLUSIONS

Despite high heterogeneity, we confirm the historic assumption that ARR reduces during pregnancy, and demonstrate an overall reduction in ARR over time. Studies using data originating from claims databases demonstrated a lower relapse rate at all time points, which has not previously been demonstrated.

Women's Health: Contemporary Management of MS in Pregnancy and Post-Partum

Multiple sclerosis (MS) primarily affects women in childbearing age and is associated with an increased risk of adverse post-partum outcomes. Relapses and now fetal exposure to disease modifying treatments in the early phase of pregnancy and thereafter are of concern. Safe and effective contraception is required for women who wish to delay or avoid pregnancy while on disease-modifying treatments. Counseling and planning is essential to assess the risk of both fetal and maternal complications, particularly now in the era of highly efficient and riskier therapies. The purpose of this review is to provide a practical framework using the available data surrounding pregnancy in MS with the goal of optimizing outcomes during this phase in MS.

Natural Parenting — Back to Basics in Infant Care

This review examines an age-old approach to parenting recently rediscovered in Western industrialized societies and known by names such as natural parenting, attachment parenting, and instinctive parenting. Its leading principle is utmost sensitivity to the child's innate emotional and physical needs, resulting in extended breastfeeding on demand, extensive infant carrying on the caregiver's body, and cosleeping of infant and parents. The described practices prevailed during the evolutionary history of the human species and reflect the natural, innate rearing style of the human species to which the human infant has biologically adapted over the course of evolution. An overview of research from diverse areas regarding psychological as well as physiological aspects of early care provides evidence for the beneficial effects of natural parenting. Cross-cultural and historical data is cited to reveal the widespread use of the investigated parenting style. It is concluded that the described approach to parenting provides the human infant with an ideal environment for optimal growth both psychologically and physiologically. It is yet to be determined how much departure from this prototype of optimal human parenting is possible without compromising infant and parental wellbeing. The review also invites a critical reevaluation of current Western childrearing practices.

Pituitary–ovarian axis during lactational amenorrhoea. I. Longitudinal assessment of follicular growth, gonadotrophins, sex steroids and inhibin levels before and after recovery of menstrual cyclicity

BACKGROUND

Comparisons of follicular development and hormonal profile in the same women during and after lactational amenorrhoea (LA) are scarce. We report follicular growth, pituitary and ovarian hormone serum levels in the same women during LA and in follicular phases after resumption of menstrual cyclicity.

METHODS

Serum samples were obtained from 10 women during LA between days 60 and 89 post-partum and between days 1 and 4 (early follicular phase; EFP) and 7 and 10 (mid-follicular phase; MFP) of the second and third cycles after LA.

RESULTS

The number of follicles >3 mm and diameter of the largest follicle were significantly higher during LA when compared to EFP and MFP. Serum levels of inhibin B were similar in LA and EFP and increased significantly in MFP. Pro-alphaC was significantly higher in EFP than in LA and MFP. Estradiol was similar during all stages. In comparison with EFP and MFP, LA is associated with higher prolactin levels, normal or slightly elevated gonadotrophins and increased number and size of follicles without a parallel increase in estradiol, inhibin B and Pro-alphaC.

CONCLUSIONS

During LA, there is a profound dissociation between follicular growth and follicular endocrine activity, which suggests an alteration in the stimulus-response relationship at the follicular level.

The association of progesterone, infant formula use and pacifier use with the return of menstruation in breastfeeding women: a prospective cohort study

OBJECTIVES

This study sought to explore hormonal and postnatal factors, which are associated with the return of menstruation in breastfeeding mothers.

DESIGN

A prospective cohort study in Bristol, UK. Ninety-one breastfeeding mothers of mixed parity were recruited at community-based antenatal clinics. Eighty-five mothers completed all stages and informed us about the return of menstruation. Data were collected from interviews and questionnaires antenatally, immediately postnatally, and 1 week, 4 weeks and 6 months later. Blood samples were taken at all time points except at 6 months. Associations between hormone levels, postnatal factors and the return of menstruation were explored using univariate and multivariate statistical survival analysis.

RESULTS

Sixty-five (76%) mothers were still breastfeeding at 6 months and 46 (54%) of these were fully breastfeeding (not giving formula milk); 21 (32%) mothers started menstruating in the first 6 months whilst they were still breastfeeding and 14 were fully breastfeeding at 6 months. Survival analysis modelling showed that formula use (RR=4.27; 95% CI=1.89, 9.67), pacifier (dummy) use (RR=3.26; 95% CI=1.35, 7.84) and lower postnatal progesterone levels (P=0.006) each made a significant contribution to the chance of earlier resumption of menstruation. Prolactin and oestradiol levels showed no associations with the return of menstruation.

CONCLUSIONS

Higher postnatal progesterone levels are associated with delayed menstruation; while the use of pacifiers and infant formula milk are associated with an earlier return to menstruation.

Lactation and maternal bone health

Women lose bone during lactation, and this is an important mechanism to provide calcium for human milk. Bone loss during lactation occurs even in women with high calcium intakes. Lactation-induced bone loss is transient because bone density increases rapidly after weaning. Bone loss during lactation and recovery after weaning are related to ovarian function and the length of postpartum amenorrhea. The recovery of bone after weaning can occur with shortly spaced pregnancies. Women who have breastfed several infants do not have reduced bone density after menopause. Overall, the transient bone loss during lactation does not seem to increase a woman's risk of osteoporotic fracture in her elder years. Further research is needed on special subgroups of women, such as adolescents, women who are vitamin D deficient or have extremely low calcium intakes, and women who have simultaneously breastfed multiple infants to determine whether these women are able to regain sufficient bone mass after lactation to preserve their bone health.

Lactational amenorrhea/anovulation and some of their determinants: a comparison of well-nourished and undernourished women

OBJECTIVE

To study the effect of maternal nutritional status and some other possible determinants on lactational amenorrhea/anovulation.

DESIGN

Prospective matched-pairs study.

SETTING

Postpartum wards and community and academic settings.

PATIENT(S)

Thirty matched pairs of otherwise healthy, well-nourished (body mass index > or = 26.00 kg/m2) and undernourished (body mass index < or = 19.00 kg/m2) postpartum women were selected.

INTERVENTION(S)

Infant feeding pattern was recorded weekly, and infant weights, maternal body mass index, and maternal PRL levels were estimated every 4 weeks until resumption of menstruation. Ovulatory activity was determined using urinary estrone and pregnanediol glucuronide concentrations.

MAIN OUTCOME MEASURE(S)

Time of resumption of menstruation, regular and ovulatory.

RESULT(S)

Well-nourished women resumed regular menstruation significantly earlier than undernourished women but resumed ovulatory menstruation at almost the same time. Undernourished women had fewer anovulatory cycles preceding first postpartum ovulation and a higher prevalence of formula feeding. Effect of body mass index on lactational amenorrhea became nonsignificant when nonintroduction of formula feeds, maternal age, and socioeconomic status were controlled for.

CONCLUSION(S)

Improved maternal nutritional status has no significant effect on fertility: ovulation is not advanced despite early resumption of regular menstruation.

Hormonal and dietary regulation of changes in bone density during lactation and after weaning in women

Lactating women secrete approximately 250 mg of calcium in breast milk each day. Some of the calcium used for milk production comes from bone as women experience a transient 3-9% decrease in bone density during lactation. This loss appears to be obligatory and under hormonal regulation as lactation-induced bone loss occurs even when calcium intake is high. Bone mineral is recovered after lactation ceases or menses resume. Recovery of bone mineral appears to be complete even when pregnancies and lactations are closely spaced, and lactation does not increase future risk of osteoporotic fracture. Current data point to estrogen and parathyroid hormone-related peptide as regulating bone mobilization during lactation. The typical calcium regulatory hormones, parathyroid hormone, calcitriol and calcitonin, do not appear to stimulate bone resorption during lactation. Restoration of ovarian hormone production and decreased production of PTHrP2 are likely to result in the recovery of bone mineral after lactation has ceased.

Dies endogeneity matter? A comparison of empirical analyses with and without control for endogeneity

PURPOSE

Using data from the Cebu Longitudinal Health and Nutrition Survey, we perform an empirical investigation of the effects of endogeneity and unobserved heterogeneity in the analysis of health outcomes.

METHODS

First, we lay a theoretical background for this analysis and develop a set of expectations regarding the effects of ignoring endogeneity. Then, by modeling the effect of infant-feeding patterns on time to resumption of menses, we perform parallel analyses with and without control for endogeneity.

RESULTS

We show that in this analysis, as far as the effects of endogeneity are concerned, empirical results do accord with theoretical expectations. There are differences in parameter estimates between models, that lead to somewhat different interpretations.

CONCLUSIONS

We discuss the importance and implications of these findings for epidemiological studies of health outcomes. We outline the steps involved in such an analysis and discuss the practical limitations of the methods, as well as the possible gains.

Documentation of second-by-second breastfeeding behaviors using a novel method

The specific way nursing patterns influence the duration of postpartum amenorrhea is unknown. This may result from the shortcomings of available methods: the daily log and recall. We tested these against a novel method, an event monitor (EM), consisting of a wrist-worn stopwatch that stores events. Exclusively breastfeeding women (n = 11) were assigned randomly to use each of the three methods twice during a 2-week period surrounding Weeks 4, 8, and 12 postpartum. More nursing episodes were recorded with the EM than log during Week 4 (p < 0.03) and Week 8 (p < 0.02). EM captured more episodes than recall during all study periods (p < 0.004). The EM was considered as acceptable and accurate to mothers as the other methods and, therefore, is a useful option for documenting breastfeeding patterns.

Longitudinal analysis of the effects of infant-feeding practices on postpartum amenorrhea

The Cebu Longitudinal Health and Nutrition Survey is used to examine the effect of various components of infant-feeding patterns on return of menses postpartum. The results show that factors such as active suckling, the use of two breasts versus one, breast-feeding on demand versus on a fixed schedule. and the feeding of other milks and of nonnutritive or low-caloric other liquids can be important under selected circumstances. Discrete-time logistic hazards modeling is used to estimate the weekly probability of return to menses.

Prolactin response to suckling and maintenance of postpartum amenorrhea among intensively breastfeeding Nepali women

The aim of the study was to determine the association between PRL responses to suckling and maintenance of postpartum amenorrhea among breastfeeding mothers. Three blood spot samples (5, 30, and 50 min following a timed nursing bout) were collected from 71 intensively breastfeeding Nepali women for PRL determination. Maternal age, BMI (weight/height2), menstrual status, caste, infant age, nursing bout length, and duration of supplementation were recorded at time of sample collection. Independent and paired t tests, linear regression analyses, and general linear models were used to evaluate differences between cycling (n = 36) and amenorrheic (n = 35) women and associations among variables. Logistic regression analyses were used to relate PRL measures to the odds of maintaining lactational amenorrhea. Amenorrheic breastfeeding mothers had higher (P < .001) PRL levels at all 3 collection times than cycling breastfeeding mothers, and PRL levels declined with time since birth (P < 0.05). The odds (OR) of having ceased lactational amenorrhea was significantly higher (OR = 5.0, 95% Cl = 1.3-19.9) among mothers with lower PRL levels (< or = 10 ng/mL) at 50 min post-sucking, and PRL at 50 min showed a significant dose response relationship with menstrual status. The association between 50 min PRL levels and lactational amenorrhea appears to be independent of time postpartum, maternal age, BMI, nursing bout length, and duration of supplementation. Among intensively nursing women, maintenance of elevated PRL levels across the interbout interval increases the odds of maintaining lactational amenorrhea.

Lactational anovulation in non-human primates: restriction of nursing inhibits Prl secretion without precipitating the return of ovulatory menstrual cyclicity in cynomolgus monkeys

To test the hypotheses that nighttime suckling and elevated nocturnal prolactin concentrations are essential for the continuation of lactational anovulation, the effects of restricting nursing to twelve h per day (either day or night) on maternal prolactin (Prl) levels and resumption of ovulatory menstrual cycles were studied in five groups of cynomolgus monkeys: Group 1: baby weaned: Group 2: baby fully nursed: Group 3: baby nursed night only; Group 4: baby nursed day only; and Group 5: baby housed with mother but not allowed to nurse. Restrictions were initiated at approximately 150 days postpartum and were achieved by placing a non-nursing jacket over the nursing jacket, which was worn 24 h/day. Fifteen out of seventeen monkeys remained anovulatory while housed with their infants, irrespective of the type of nursing restriction. First postpartum ovulations occurred approximately two months post-weaning. Plasma prolactin concentrations during both day and nighttime were significantly (p < 0.05) greater in the fully nursing group(s) than in all other groups. Fully nursing mothers had significantly (p < 0.01) greater prolactin concentrations at night than during the day. Among the restricted groups, the night only suckling group had significantly greater prolactin concentrations at night than the other restricted groups. There were no differences between daytime values, and within each restricted group there were no significant differences between day and night prolactin levels. We conclude that 1) nighttime suckling is not an absolute prerequisite for sustained lactational anovulation, and 2) suckling-induced hyperprolactinemia is not the principle mediator of lactational anovulation.

Serum inhibin during lactation: relation to the gonadotrophins and gonadal steroids

OBJECTIVE

The aims of the study were to describe the changes in serum immunoreactive inhibin (INH) during normal lactation and to examine the relations between INH, oestradiol (E2) and follicle stimulating hormone (FSH), particularly during the first weeks post partum.

DESIGN

Blood samples were obtained from normally lactating women for hormone measurements at daily intervals until discharge from hospital, and subsequently at weekly intervals until the resumption of menses, or one year post partum.

SUBJECTS

Eighteen breast feeding women aged 27-36 years volunteered for the study.

MEASUREMENTS

INH, FSH, luteinizing hormone (LH), prolactin (PRL), E2, and progesterone (P4) were measured by standard radioimmunoassays. Non-linear modelling was used to quantify the hormone patterns observed.

RESULTS

Hormone levels were compared with those found in the follicular phase of the normal menstrual cycle. Levels of INH fell rapidly in the first week post partum and remained at the lower end of the follicular phase range for the period of study, rising only just prior to resumption of menses. E2 fell more slowly, into the follicular phase range, reaching the lower end of that range only at about approximately 100 days post partum. FSH levels were suppressed initially below the follicular phase range, commencing to rise 4.7-24 days post partum, reaching a plateau high in the follicular phase range 17.5-53 days post partum, and subsequently showing a slow decline. Human chorionic gonadotrophin (hCG), initially measured because of its cross-reactivity in the LH assay, fell rapidly post partum and LH remained in the low follicular phase range for several weeks. PRL fell slowly throughout and was still elevated at 150 days post partum, while P4 fell very rapidly and was less than 1 nmol/l until just prior to first menses.

CONCLUSIONS

Inhibin levels fall rapidly post partum and remain low until close to the time of resumption of follicular activity and menses. The post partum rise in serum FSH appears to be much more closely related to falling oestradiol levels than to the very early and rapid fall in inhibin. Oestradiol thus appears to be the predominant negative feedback factor influencing FSH secretion during the post partum period. The low inhibin levels may allow FSH to rise to levels high in the follicular phase range under the predominant negative feedback control of oestradiol. Inhibin levels do not appear to be a suitable marker of returning fertility.

Factors related to duration of postpartum amenorrhoea among USA women with prolonged lactation

Duration of postpartum amenorrhoea (PPA) was compared among women who breast-fed for > or = 6 months (breast-feeding group) or < or = 3 months (formula-feeding group) and was found to be significantly shorter among the latter. Associations between maternal factors and duration of PPA were examined. Within the formula-feeding group, the only variable associated with duration of PPA was duration of breast-feeding. Among breast-feeding mothers who resumed menstruation after 3 months postpartum, duration of PPA was positively associated with parity and negatively associated with maternal body mass index (BMI) at 3 months postpartum. Among breast-feeding mothers who resumed menstruation after 6 months, duration of PPA was positively associated with parity, pregnancy weight gain, number of night feeds and milk volume at 6 months, and negatively associated with maternal age and BMI at 6 months postpartum. These results indicate that maternal anthropometric status is related to duration of PPA, even in a relatively well-nourished population of lactating women.

Prolactin response to suckling in a group of fully breast feeding women during the early postpartum period

Prolactin response to suckling was studied in a group of fully breast feeding women (N = 58) between 4-6 weeks postpartum. Basal, suckling stimulated and the increment of prolactin showed wide individual variations. Basal prolactin concentrations varied from 140 to 4,600 mIU/l, suckling stimulated prolactin from 400 to 5,600 mIU/l and the increment of prolactin from 40 to 4,160 mIU/l. Basal (p = 0.0395) and suckling stimulated (p = 0.0423) prolactin concentrations significantly increased as the number of night breast feeds increased and the suckling stimulated (p = 0.0218) prolactin concentrations significantly increased as the number of breast feeds/24 h increased. However, the magnitude of the rise in prolactin in response to suckling was not dependent on basal prolactin concentration. Basal, suckling stimulated or the increment of prolactin were not significantly different between subjects having different breast feeding frequencies, when the subjects were grouped according to the number of breast feeds. These differences may be due to the large individual variation in prolactin concentrations seen in women having similar breast feeding frequencies which may arise from individual variations in hypothalamic--pituitary response to suckling.

The feasibility of suppressing ovarian activity following the end of amenorrhoea by increasing the frequency of suckling

OBJECTIVE

To determine the feasibility of suppressing ovarian activity by increasing the frequency of suckling episodes.

METHOD

Prospective study was carried out with 19 exclusively breastfeeding volunteers. Ten subjects (experimental group) increased the suckling episodes by minimum 50% per day from the beginning of the first postpartum menses. Nine controls continued breastfeeding as before. Estradiol, progesterone, LH, FSH and prolactin were measured in blood samples, drawn twice a week up to the second postpartum menses or for 60 days, by RIA. Student's t-test was employed.

RESULT

The higher suckling frequency prevented ovulation in 7 of 10 cases examined according to the plasma progesterone concentration (< 9.5 nmol/l). Significantly higher average prolactin value could also be found in the experimental group (1038 (527) munits/l vs. 518 (245) munits/l; P < 0.05).

CONCLUSION

Results suggest that an earlier initiation of the increase in breastfeeding frequency may delay the resumption of ovulation. Frequent, full time lactation may reduce the risk of pregnancy.

Aetiological approach of female reproductive physiology in lactational amenorrhoea

There is a wide range of duration of post-partum amenorrhoea and resumption of ovulation between individuals, within an individual or between populations. Several extraneous variables, such as parity, mother's age, sex of the breast-fed baby, socioeconomic status and cultural level of the family, can be controlled; then the remaining variables will probably explain a part of the total variability in post-partum amenorrhoea duration but say nothing about the physiological process. In attempting to question physiological aspects of the return of fertility several observational studies have tended to favour one of the different factors which are supposed to play a major role in the regulation and have compared different levels of it, such as body composition of the mother (Frisch & McArthur, 1974), breast-feeding pattern (Jones, 1989) or the life style of the women. Life style can be related to women's physical activity in normal life (Ellison, 1991), the difference between urban and rural life (Carael, 1981) or the environment (Laurenson et al., 1985). Prolactin as a possible mediator of the central regulation has been carefully considered (Lunn, Austin & Whitehead, 1984; Howie et al., 1982). These studies were mainly observational rather than experimental, supplementing mothers during the lactating period or during the pregnancy. If this information is added to what is known of other animal species (Loudon, 1987) or animal experimentation (Plant et al., 1989; Williams et al., 1990a; Williams et al., 1990b), the combination of several of the main factors believed to have a major role in the human species can be clarified and the aetiology of the resumption of fertility in nursing women investigated.

The return of postpartum fertility monitored by enzyme-immunoassay for salivary progesterone

A longitudinal study in which daily salivary progesterone and estrone were measured by solid-phase enzyme-immunoassays was performed in 30 postpartum women to monitor the return of ovarian activity. Ovulation was inferred from a sustained rise in salivary progesterone over 251 pmol/l, but salivary estrone measurements were not as informative as progesterone in this regard. Recovery of ovarian activity was slower in lactating women compared with non-lactators; the mean delivery-menstruation interval were 123 (+/- 10) and 57 (+/- 7) days, respectively. An abnormal luteal phase was noted in 35% of the first ovulatory cycles, 20% had short luteal phases and 15% were less than the 5th percentile of a normal control corridor. The pregnancy rate in this study of 3.3% was lower than the anticipated rate of 8.8%. We conclude that salivary progesterone measurements are useful for monitoring the return of ovarian activity postnatally.

Is the lactational amenorrhea method a part of natural family planning? Biology and policy

The lactational amenorrhea method is a natural method of family planning for women who breastfeed their infants. The underlying physiology results in a natural suppression of ovulation, and the concomitant amenorrhea, induced by exclusive (or almost exclusive) breastfeeding. This in addition to the infant's age of 6 months or less and specific feeding pattern are the parameters used to identify the possible return of fertility. The lactational amenorrhea method provides at least 98% protection against pregnancy. Data from a recent multicenter study of breastfeeding support the use of the lactational amenorrhea method as a natural family planning method. The lactational amenorrhea method can be incorporated into natural family planning programs and teaching.

Contraceptive efficacy of lactational amenorrhea in urban Chilean women

The contraceptive efficacy of breastfeeding was assessed in 236 healthy urban women who were followed at monthly intervals during the first postpartum year. Proportional hazard models were used to evaluate the influence of time postpartum, menstrual status and breastfeeding pattern upon the risk of pregnancy. Time and menstrual status had a highly significant effect on this risk. Those women who remained in amenorrhea had cumulative probabilities of pregnancy of 0.9% and 17% at 6 and 12 months postpartum, respectively. In those who recovered menstrual cycles, the risk rose to 36% and 55% at 6 and 12 months, respectively. Milk supplementation also increased significantly the risk when considered alone but not when time and/or menstrual status were included in the analysis. However, amenorrheic women who introduced bottle feeding, had a higher risk of pregnancy after 6 months postpartum than those who remained fully nursing. The analysis was unable to detect a significant influence of the nursing frequency. The results confirm that lactational amenorrhea is an effective contraceptive during the first six months postpartum. The first postpartum bleeding marks a great increase in the risk of pregnancy. Supplementation also increases the risk, particularly in amenorrheic women.

The effect of initiation of child supplementation on resumption of post-partum menstruation

The effects of initiation of solid and liquid supplementation on resumption of post-partum menstruation are examined, using data from a 2-year prospective study of birth interval dynamics from central Java, Indonesia. The sample analysed consisted of 444 women who experienced resumption of menses while breast-feeding, women who were breast-feeding and amenorrhoeic at the end of the study, or women who resumed menstruation or were censored after infant mortality and weaning which preceded the resumption of menses. Multivariate hazard model analysis was used to assess the significance of supplementation, various breast-feeding covariates, and age and parity of the dependent variable. Because the timing of supplementation varies, the supplementation variables were introduced into the analysis as time-varying covariates. For the mothers in the sample, solid and liquid supplementation was initiated at medians of 2.1 and 8.0 months respectively. The former had a significant effect on resumption of menses, while the latter was only marginally significant. Earlier supplementation meant shorter durations of amenorrhoea for the majority of women. However, the effect was not consistent across all categories of women. For the small group of mothers who were low intensity breast-feeders (less than or equal to 6 minutes per nursing episode) or as low frequency day-time breast-feeders (less than or equal to 6 nursing episodes per day-time), earlier supplementation had no additional effect on their rate of resumption of menses post-partum.

Nursing behaviour and its relation to duration of post-partum amenorrhoea in an Andean community

Nuñoa is a high altitude rural Peruvian community characterized by socioeconomic stratification and differential access to the market economy. Nursing practices and the effects of nursing are also stratified; this translates into a risk of menses at 12 months post-partum nearly seven times greater in wealthier than in poorer women. Most nursing occurs in the morning, among those who practice on-demand breast-feeding. Nursing episodes are clustered into sessions; the amount of breast-feeding is regulated by varying the number of episodes per session rather than by changing the duration of suckling episodes or the frequency of sessions per hour. Thus, resumption of ovulation is not dependent on the variable spacing of nursing episodes or sessions. The components of nursing activity most likely to be responsible for variation in the duration of post-partum amenorrhoea in these nursing women are mean session duration and mean number of episodes per session. The mean duration of morning nursing sessions is negatively associated with infant's age, reflecting the greater reliance of younger children on breast-milk. The mean duration of afternoon nursing sessions is positively associated with mother's age, independent of infant's age, possibly reflecting maternal age-related variation in milk production capabilities. Baby minding by older daughters may also help to explain variation in afternoon nursing.

Breast-feeding and post-partum amenorrhoea in Indonesia

The association between breast-feeding patterns and resumption of menses post-partum was examined in a prospective study in Indonesia. In order to examine these relationships directly in a longitudinal study, it was first necessary to distinguish among women who experienced infant mortality before menses resumed, women who weaned before menses resumed, and women who had return to menses while breast-feeding. Information on suckling patterns and menstrual status was collected by recall for 444 women at monthly visits for 2 years. Three main breast-feeding variables, minutes per episode, number of episodes per day, number of episodes per night, and other breast-feeding variables were derived for each woman, to give the average nursing pattern up to menses or the end of the study, which-ever came first. While high levels of nursing for each of these three main variables were found to be significantly related to delay in return of menses post-partum, the interactions between more minutes per episode, and more frequent day- and night-time feeds, were found to be the most important factors in the delay in onset of post-partum menstruation in those women whose menses resumed while still nursing or who remained amenorrhoeic and nursing at the end of the study.

Lactational amenorrhea and the recovery of ovulation and fertility in fully nursing Chilean women

The probability of experiencing the first postpartum bleeding, the first ovulation and the risk of pregnancy during exclusive breastfeeding was assessed in a selected group of urban Chilean women. Admission criteria included having had a normal pregnancy and a vaginal term delivery of a healthy infant and the desire to maintain breastfeeding for as long as possible. The risk of bleeding and the recovery of ovulation was assessed in 48 women selected for being amenorrheic and fully nursing at day 75 postpartum and their willingness to participate in the blood sampling protocol. The first bleeding and ovulation was experienced while fully nursing by 28% and 26% of these subjects, respectively, at day 180 postpartum. The probability of experiencing the first bleeding and the probability of pregnancy during full nursing were calculated for 236 women not contracepting who were enrolled during the first month postpartum. The cumulative probability of bleeding and of pregnancy was 52% and 9.4% at day 180 postpartum, respectively. The risk of pregnancy was less than 2% in the subset of amenorrheic cases. In this urban population selected for having the highest motivation and best breastfeeding performance, the association of breastfeeding with infertility was too weak to serve as an effective birth spacer, except for the period of lactational amenorrhea. When the first postpartum bleeding took place before the sixth postpartum month in fully nursing women, it had a good predictive value to indicate the onset of a higher risk period.

A study on the feasibility of suppressing ovarian activity following the end of postpartum amenorrhoea by increasing the frequency of suckling

The aim of the study was to test the effect of increasing the frequency of breastfeeding upon ovarian function following the end of postpartum amenorrhoea. Women exclusively breastfeeding (n = 14) who experienced their first postpartum menstruation between the third and fifth month after delivery were randomly allocated to an experimental (n = 7) and a control (n = 7) group and studied during the next two cycles. Women in the experimental group agreed to increase the number of breastfeeding episodes per day throughout the second cycle. Blood samples were drawn twice a week from the first to the third postpartum menstruation for prolactin, oestradiol and progesterone determinations. The number of breastfeeding episodes per day and night and the length of each episode were recorded daily. An average frequency of 11 nursing episodes per 24 h was reported during the first study cycle in both groups. The experimental group increased by 50% the breastfeeding frequency after the second menstruation while the control group kept its spontaneous feeding pattern. The increase of suckling frequency occurred mainly during day hours. The total breastfeeding time per 24 h was not increased. The length of the menstrual cycle was not altered by the increased suckling frequency. The endocrine pattern differed neither between the first and second cycle of the experimental group nor between the experimental and control group, with the exception of PRL levels which were higher in the experimental group throughout both cycles. Twenty cycles (71%) showed progesterone values compatible with ovulation (greater than 9.5 nmol/l). The highest progesterone values and the highest oestradiol values observed in the ovulatory cycles of lactating women were within the range found in non-nursing fertile women. Plasma levels of PRL were significantly elevated in all cycles but one, in comparison with PRL levels in non-nursing women. It is concluded that if cyclic ovarian function is reestablished early in fully nursing women, a mere increase in the number of breastfeeding episodes, without augmenting total suckling time and the frequency of nocturnal episodes, does not provide a sufficient stimulus to resuppress the pituitary-ovarian axis.

The recovery of ovarian function during breast-feeding

The pattern of breast-feeding was daily recorded and the serum concentrations of prolactin (PRL), FSH, LH, estradiol (E2) and progesterone (prog) were measured at weekly intervals in 26 breast-feeding mothers from the time of delivery and up to the resumption of regular ovulation or to the end of the first postpartum year. Twelve postpartum non-breast-feeding women were similarly studied as controls. An algorithm was used to characterize ovulatory events into three types: the first, with evidence highly suggestive of normal ovulation (EHSO), the second, with evidence of probable ovulation (EPO) and the third with evidence indicating questionable ovulation or deficient corpus luteum function (QO/DCT). Pregnancy preceded the first menstruation in one woman in each of the breast-feeding and control groups. Of the 19 breast-feeding women who started to menstruate during the first postpartum year, five had EHSO, one had EPO, 5 had EQO/DCL and 7 had anovulatory (AO) menstruation. The corresponding figures in the 11 controls were 6, 2, 3 and 0. Pregnancy occurred before a second menstruation in one woman in both the study group and the controls. In 18 breast-feeding women observed, the second menstruation was preceded by EHSO in 7, by EPO in 3, by EQO/DCL in one and AO in 7. In 10 controls the corresponding figures were 7, 3, 0 and 0. Out of a total of 79 menstruations observed during breast-feeding the incidence of AO was 30% and of QO/DCL was 15%. In actively breast-feeding mothers, hyperprolactinemia persisted for more than 1 yr. However, menstruation and ovulation occasionally occurred before the drop of PRL to concentrations seen during the normal menstrual cycle. In the majority of women, low E2 levels were present during lactational amenorrhea, but with occasional spikes in some. A few women maintained somewhat high values of E2 for several weeks before the resumption of menstruation. The implications of these hormonal findings to the attempts to improve on the contraceptive effect of breast-feeding are discussed.

Nursing practices and lactation amenorrhoea

The study examines the effects of nursing practices on the duration of lactation in middle-class American women. Thirty-two nursing mothers were followed for 2 years post-partum, data being collected at eight home visits by interview and by nursing records kept by the mothers. Those women who nursed frequently (>8/day) during exclusive breastfeeding remained amenorrhoeic longer than infrequent nursers, introduced supplements later and did not resume menses as promptly thereafter. They continued an hour or more of night nursing during supplemented nursing. Duration of exclusive nursing and night nursing after supplementation were the major influences on duration of amenorrhoea. Mothers' age, weight-for-height, and nursing frequency before supplementation showed no significant effect but night nursing after supplementation was a major factor in post-supplementation duration of amenorrhoea. Those women who both supplemented later and maintained an hour of night nursing after supplementing remained amenorrhoeic for 6–10 months longer than those who supplemented early and/or reduced subsequent night nursing.

Comparative study of nursing mothers in Africa (Zaire) and in Europe (Sweden): breastfeeding behaviour, nutritional status, lactational hyperprolactinaemia and status of the menstrual cycle

A total of 1036 nursing mothers were investigated for their nursing behaviour, status of nutrition and menstrual cycle, serum prolactin and progesterone; 61 in Sweden, 457 in an urban area of Zaïre (Bukavu, Kivu) and 518 in a rural area of the same region (Kabare, Kivu). Lactational hyperprolactinaemia is influenced by the frequency but not by the duration of suckling. The return of luteinization of follicles, but not that of menstrual bleeding, was inversely related to the degree of lactational hyperprolactinaemia. Significant luteinization took place in only some 10% of the mothers during the first three months of lactation in Sweden and within the first year in Zaïre. In these mothers with luteinized follicles the average progesterone was only slightly above 1.0 ng/ml indicating poor luteinization. Lactational hyperprolactinaemia, the return of menstruation and luteinization during lactation were not related to the nutritional status as evaluated by the body weight indices and serum albumin. However, suckling and hyperprolactinaemia do not appear to be the only factors involved in the control of fertility during lactation. When serum prolactin levels were equally low, i.e. below 500 microU/ml, twice the number of lactating mothers with signs of luteinization were found in the urban than in the rural population of Zaïre.

Lactation and birth spacing in highland New Guinea

The effects of infant suckling patterns on the post-partum resumption of ovulation and on birth-spacing are investigated among the Gainj of highland New Guinea. Based on hormonal evidence, the median duration of lactational anovulation is 20·4 months, accounting for about 75% of the median interval between live birth and next successful conception (i.e. resulting in live birth). Throughout lactation, suckling episodes are short and frequent, the interval changing slowly over time, from 24 minutes in newborns to 80 minutes in 3-year olds. Maternal serum prolactin concentrations decline in parallel with the changes in suckling patterns, approaching the level observed in non-nursing women by about 24 months post-partum. A path analysis indicates that the interval between suckling episodes is the principal determinant of maternal prolactin concentration, with time since parturition affecting prolactin secretion only in so far as it affects suckling frequency. The extremely prolonged contraceptive effect of breast-feeding in this population thus appears to be due to (i) a slow decline in suckling frequency with time since parturition and (ii) absence of a decline over time in hypothalamic–pituitary responsiveness to the suckling stimulus.

Prolactin and the return of ovulation in breast-feeding women

Cross-sectional studies in Australia and the Philippines and a longitudinal prospective study in a selected Australian sample of breast-feeding mothers have shown that basal serum prolactin (PRL) concentrations are elevated during 15–21 months of lactational amenorrhoea.

A predictive model of serum PRL levels and return of cyclic ovarian activity during full breast-feeding, partial breast-feeding and weaning has been developed from the results of breast-feeding behaviour and serum PRL, gonadotrophin and oestradiol measurements in 34 mothers breast-feeding on demand for a mean of 67 weeks.

Breast-feeding patterns influence serum PRL levels. Important factors during full breast-feeding are the age of the baby, the longest interval between feeds at night and total 24-hr suckling time, and following the introduction of supplements, the mean interval between feeds, together with the total 24-hr suckling time and the number of solid supplements per day.

The precise mechanisms whereby breast-feeding regulates cyclic ovarian activity remain unknown. Gonadotrophin secretion appears to be quantitatively normal, but qualitative changes, secondary to altered hypothalamic activity, may be the most important factor. A direct inhibitory effect of PRL on ovarian follicular development and steroidogenesis remains possible.

Ovulation with a normal luteal phase is probable for 30% of breast-feeding mothers before the first menses, but is unlikely before 6 months, provided breast-feeding is frequent day and night.

Measurement of serum PRL is a sensitive index of the return of menstruation and fertility during lactation in the population studied.

Use of a superactive luteinizing hormone releasing hormone (LHRH) agonist in the treatment of menorrhagia

A luteinizing hormone releasing hormone agonist, D-Ser(But)6des Gly10-LHRH ethylamide, was administered intranasally to four women with unexplained ovulatory menorrhagia. Dramatic reductions in excessive menstrual blood losses were induced without significant side-effects, although the pattern of loss returned to pretreatment levels within 2 months of ceasing therapy.

Pulsatile secretion of LH in relation to the resumption of ovarian activity post partum

Changes in the pulsatile pattern of LH secretion in relation to the resumption of ovarian activity post partum have been studied in breast feeding mothers. Basal concentrations of LH were significantly lower than normal both when ovarian activity was completely suppressed and when there was evidence of some follicular development prior to the resumption of menstruation. Once menstruation resumed basal concentrations of LH were unchanged whether ovulation occurred or not. No difference in the frequency or amplitude of pulses in LH secretion could be found at any stage post partum in either breast or bottle feeding women. FSH levels remained constant throughout the post partum period while mean concentrations of prolactin fell as ovarian activity returned to normal. However, during the period of complete suppression of ovarian activity in breast feeding women, two patterns of pulsatile secretion of LH were observed. In 76% of observation periods, basal levels of LH were lower than normal and were characterized by low frequency and low amplitude pulses of LH. In contrast, in the remaining 24% of observation periods, basal levels and pulse amplitude and frequency of LH were similar to those in the follicular phase of normal menstrual cycles in these women. Individual women showed either or both of these patterns of secretion during the period of ovarian suppression post partum. The data suggests that the failure to maintain ovarian follicular development post partum in breast feeding women may be due to: (1) a direct block of LH action at ovarian level, perhaps by the high levels of prolactin associated with lactation and/or (2) an inability of the hypothalamic-pituitary axis-as a result of the suckling stimulus and/or prolactin-to maintain pulsatile secretion of LH in the face of the negative feedback effects of the increased oestrogen secretion resulting from the initiation of follicular development.

Nutritional thriftiness and human reproduction: beyond the critical body composition hypothesis

The 'critical body composition hypothesis' (CBCH) is frequently used to explain variations in the duration of postpartum amenorrhea. The hypothesis predicts that ovulation will not occur it fat reserves fall below a critical threshold. This paper attempts to analytically separate the CBCH from the broader concept of nutritional thriftiness on which it is based. A review of previous research on fat cell metabolism and ovulation finds no direct link between fatness and fecundity. Rather they are each regulated by the lactation and mother-infant interactions associated with breast feeding. As a system which delivers available fat into breast milk and prevents ovulation only during the time when the infant is dependent on the mother, the pathways outlined here represent a nutritionally thrifty method of fertility regulation, one which maximizes reproductive success while minimizing energy investment. The cultural patterning both of infant feeding behaviors and the wider range of maternal activities which affect breast feeding suggest specific testable hypotheses to explain interpopulation variations in fertility and infant nutritional status.

Intranasal treatment with luteinising hormone releasing hormone agonist in women with endometriosis

An agonist analogue of luteinising hormone releasing hormone (buserelin) was successfully used to treat women with endometriosis. A dose of 200 micrograms administered intranasally thrice daily was found to be effective in five patients, in whom the endometriotic lesions resolved after six months' treatment. Failure occurred in a sixth patient, who received only 400 micrograms once daily. Anovulation was induced in all subjects together with suppression of menstruation after the first month of treatment. Symptoms of abdominal pain, dysmenorrhoea, and dyspareunia were relieved during treatment, and one previously infertile patient conceived within two months of stopping treatment. No side effects were reported with this dosage, and the results suggest a new form of treatment for patients with endometriosis.

Norethisterone levels in maternal serum and milk after intramuscular injection of norethisterone oenanthate as a contraceptive

There is concern that the breast-fed infant whose mother is receiving intra-muscular progestogens for contraception will be exposed to significant quantities of the steroid. Norethisterone levels in maternal serum and milk were studied throughout an injection interval after intramuscular administration of 200mg norethisterone oenanthate. Milk samples were taken at the beginning and at the end of the feed. Norethisterone concentrations in milk were very much lower, but declined more slowly, than serum concentrations. Post-suckling concentrations were higher than pre-suckling concentrations. Experiments in adults receiving an oral dose of norethisterone in cow's milk comparable to that ingested by an infant in a day resulted in low serum levels. It is concluded that only very low concentrations of norethisterone would be present in the infant's circulation.