Studies in sow reproduction: 5. The effect of lactation length of the so w on the subsequent embryonic development

Forty-five female pigs (sows) were allocated at random to one of three lactation lengths: 7 days, 21 days, 42 days. All sows were remated at the first post-weaning oestrus and were slaughtered at 20 days post coitum. The reproductive tracts were removed, dissected and examined. Ovulation rates as determined by luteal count were similar for all three groups, but the number of viable embryos decreased significantly (P < 0·05) from 13·0 for the 42-day lactation group to 9·2 for the 7-day lactation group. This difference was reflected in a significant (P < 0·01) reduction in the percentage embryo survival rate as lactation length was reduced. Uterine lengths for the 7-day lactation group were significantly (P < 0·05) shorter than the other two groups. Six sows in each treatment group were blood sampled: at weaning, at remating, at 2 days post-mating, at 10 days post-mating and at 20 days post-mating. The plasma samples obtained were assayed for progesterone. No differences were observed between treatment groups for plasma progesterone concentration at any of the sampling times. It is concluded that the reduction of the litter size at the next farrowing following a short lactation length is largely a result of increased embryo death in the first 20 days of gestation.

Studies in sow reproduction: 4. The effect of level of feeding in lactation and during the interval from weaning to remating on the subsequent reproductive performance of the early-weaned sow

Seventy-five enzootic pneumonia-free female pigs (sows) were allocated at random to one of five treatment groups. Four of these groups were weaned following a 10-day lactation period and were fed either 2 or 4 kg per day in lactation and either 2 or 4 kg per day from weaning to remating, such that the patterns of feeding for the four groups in the two periods were: 4 kg, 4 kg (HH); 4 kg, 2 kg (HL); 2 kg, 4 kg (LH) and 2 kg, 2 kg (LL). A fifth treatment group (control) was weaned following a 42-day lactation period and was fed up to 6·3 kg/day, depending on litter size and 2·7 kg/day from weaning to remating. Level of feeding for the four early-weaned groups in both lactation and in the interval from weaning to remating significantly (P < 0·001) affected the weight changes of the sows during these periods. The interval from weaning to oestrus for the early-weaned sows (8·2 days) was significantly (P < 0·001) greater than for the control sows (4·5 days), but this interval was not affected by level of feeding either in lactation or in the remating period for the early-weaned sows. Litter size at the subsequent farrowing for the early-weaned sows (9·3 piglets) was significantly (P < 0·001) less than litter size for the control sows (12·0 piglets). Level of feeding in lactation or in the weaning to remating period had no effect on subsequent litter size of the early-weaned sows.

The effects of oral contraceptive use on iron and copper concentrations in breast milk

OBJECTIVE

To determine the effects of oral contraceptive (OC) treatment on maternal iron and copper metabolism during lactation.

DESIGN

Observational study.

SETTING

Private and public clinics in Brazil.

PATIENT(S)

Lactating mothers attending the family planning clinic of the University of Brasilia.

INTERVENTION(S)

The OCs used were a combination pill (0.15 mg of levonorgestrel and 0.03 mg of ethinyl estradiol) and a minipill (0.35 mg of norethidrone). Blood and breast milk samples were collected before and after a measured period of OC treatment.

MAIN OUTCOME MEASURE(S)

Iron and copper concentrations were studied in the serum and breast milk of 54 breast-feeding mothers who had been advised by their physicians to use an OC, and in a control group.

RESULT(S)

Regression analysis was performed using a model that took into consideration socioeconomic status, number of children, duration of previous lactation, type of OC, length of treatment, and age. Repeated measurements (before and after OC treatment) showed that only copper concentrations in breast milk were significantly affected by stage of lactation. During the study period, which varied from 2-15 weeks, the decline in iron concentrations in breast milk was negligible, whereas copper concentrations decreased by 50%.

CONCLUSION(S)

The use of OCs does not appear to affect significantly the secretion of iron and copper in breast milk during the first 6 months of lactation.

Bone mineral density of the spine and femur in healthy Saudi females: relation to vitamin D status, pregnancy, and lactation

Bone mineral density (BMD) measurements of the anterio-posterior lumbar spine and the proximal femur using dual-energy x-ray absorptiometry, as well as relevant clinical and biochemical parameters, were determined in 321 healthy Saudi females in order to establish reference values and to study the effects of physical and lifestyle factors on BMD. Mean +/- SD of age, body mass index (BMI), number of pregnancies, and total duration of lactation were 35.4 +/- 11.3 years, 26.5 +/- 5.2 kg/m2, 3.1 +/- 3.1, and 23.7 +/- 42.4 months, respectively. Mean +/- SD of serum calcium, 25-hydroxyvitamin D (25OHD), and PTH levels were 2.37 +/- 0.09 mmol/liter, 24.5 +/- 17.2 nmol/liter, and 52.0 +/- 30.8 pg/ml, respectively. Peak BMD values were observed around age 35 years at the spine and earlier at the femur. Compared with USA females, Saudi females had lower weight-matched Z scores at the spine (-0.126 +/- 1. 078, P = 0.04), femoral neck (-0.234 +/- 0.846, P < 0.0001), and Ward's triangle (-0.269 +/- 1.015, P < 0.0001). Further, the prevalence of osteopenia and osteoporosis in subjects >/=31 years old were 18-41% and 0-7%, respectively, depending on the site examined. Severe hypovitaminosis D (25OHD level </=20 nmol/liter) was present in 52% of the subjects. However, there was no correlation between 25OHD level and BMD at any site. Parathyroid hormone (PTH) levels correlated significantly with 25OHD levels (r = -0.28, P < 0.0001) and with weight-matched BMD Z scores at the spine (r = -0.17, P = 0.005), femoral neck (r = -0.16, P = 0.007), and Ward's triangle (r = -0.2, P = 0.0008), suggesting that the distribution of 25OHD levels in the cohort is below the threshold needed for maintaining normal BMD. On the other hand, number of pregnancies and total duration of lactation correlated with weight-matched BMD Z scores at the spine (r = -0.17, P = 0.003; r = -0.1, P = 0.08, respectively). We conclude that BMD in healthy Saudi females is significantly lower than in their USA counterparts. This may be due in part to increased number of pregnancies and longer duration of lactation together with prevalent vitamin D deficiency. http://link.springer-ny.com/link/service/journals/00223/bibs /65n1p23. html

Worldwide trends in DDT levels in human breast milk

BACKGROUND

Concern over human breast milk contamination with the pesticide DDT (1,1,1-trichloro-2,2-bis(chlorodiphenyl)ethane) has prompted numerous studies around the world during the last five decades. This article examines trends in reported DDT levels, and the apparent effect of restrictions on DDT use.

METHODS

More than 130 published values for DDT in human milk since 1951 were compiled, and trend lines were fit for regions of the world.

RESULTS

Population means have declined in much of the world, from 5000-10000 microg DDT/kg milk fat to around 1000 today in many areas. Although different regions have different means, the decline seen in various countries corresponds to their restricting DDT use.

DISCUSSION

DDT concentrations in human milk have declined in most areas of the world, consistent with restrictions on its use. Nevertheless, levels can be high in areas still using DDT, even higher than the World Health Organization's recommended limit for infants. These results indicate that population averages can be reduced by a predictable amount as DDT use is restricted.

Use of a single implant of elcometrine (ST-1435), a nonorally active progestin, as a long acting contraceptive for postpartum nursing women

Because of its unique features, the contraceptive effectiveness and tolerance during breast-feeding of 16-methylene-17 alpha-acetoxy-19-nor-4-pregnene-3,20-dione (elcometrine), delivered within a single subdermal capsule of medical grade polydimethylsiloxane, was investigated. Unlike other progestational steroids, elcometrine has no affinity for androgen and estrogen receptors and is inactive by the oral route. A total of 66 breast-feeding women receiving elcometrine by the subdermal route were enrolled in the study, and 69 women who elected to use Copper-T380 intrauterine devices (IUD) served as control subjects. The women and their infants were observed until the end of the first postpartum year. There were no significant differences in growth and development measurements among the infants in the elcometrine and control groups. The percentage of infants continuing to breast-feed at 3 and 6 months was significantly higher in the elcometrine group. There were no significant differences between the concentration of elcometrine in the mother's blood and milk. At 75 days, blood levels of elcometrine in the infants were near the undetectable and were significantly lower than the levels in maternal blood or milk (p < 0.01). In 15 of 25 infants, blood levels of elcometrine were at the limit of assay sensitivity or undetectable. Two pregnancies occurred in women using IUD, whereas none occurred in those using implants. There were menstrual bleeding irregularities in both groups. A single elcometrine capsule placed subcutaneously at 6-monthly intervals appears to be an effective method of contraception for lactating women and results in blood concentrations of nursing infants at or near undetectable levels.

Calcium and phosphorus in milk of Brazilian mothers using oral contraceptives

OBJECTIVE

Oral contraceptives (OC) are the most efficient method of contraception and it is the most prescribed by doctors in developing countries. Therefore we studied the effects of combination pill and mini-pill on calcium and phosphorus in milk of breast-feeding mothers at different stages of lactation.

METHODS

Fifty-four breast-feeding mothers made up three study groups: 33 mothers who had been advised by their doctors to use either combination pill (12), or mini-pill (21), as well as a control group of 21 mothers that used no hormonal contraceptives. All mothers completed a questionnaire and provided samples of milk before and after a measured period of observation. Mean duration of study was 76, 120, and 101 days, respectively for users of mini-pill, combination pill, and controls. Determination of calcium and phosphorus was done by inductively coupled plasma-atomic absorption spectrometry.

RESULTS

Overall the decrease in milk concentrations of phosphorus (6%) and calcium (26.3%) during the study period was not influenced by OC treatment. Regression analyses which took into consideration length of treatment, socioeconomic status, number of children, duration of previous lactation, type of contraceptive, and age of mothers and repeated measurements (before and after OC) showed that milk calcium was significantly affected by stage of lactation (p=0.0013).

CONCLUSION

The use of hormonal contraceptive such as the combination pill (levonorgestrel 0.15 mg+ethynilestradiol 0.03 mg) and mini-pill (norethindone 0.35 mg) does not seem to affect the secretion of calcium and phosphorus in milk of mothers.

Some factors related to sum-DDT levels in Ugandan mothers' breast milk

A total of 143 samples of Ugandan mothers' breast milk were analysed by gas chromatography for the presence and levels of DDT residues. The relationship between the level of DDT in the milk and the mother's age, parity, dietary habits, and place of usual residence were studied. DDT levels in the milk were not significantly related to the mother's age. Mothers nursing their first child had a significantly higher mean DDT level in their milk than those nursing their second child. Furthermore, mothers who resided in the urban area had a significantly higher mean-DDT level in their milk than those who resided in the rural area. No statistically significant differences were observed in the mean levels of DDT in the milk samples of vegetarian and non-vegetarian mothers. From the present findings, it could be concluded that milk from mothers nursing the first child and residing in an urban area is a good bioindicator for assessing exposure of lactacting mothers to DDT in Uganda.

Breast milk contamination in Kazakhstan: implications for infant feeding

To assist the Ministry of Health of Kazakhstan in making infant feeding recommendations, breast milk samples were analyzed for PCDDs/PCDFs, PCBs, chlorinated pesticides, toxic metals, and cesium-137. Sampling sites were selected to provide a profile of representative exposures to possible contaminants; 92 breastmilk samples from 7 sites were analyzed for chlorinated contaminants and 115 samples from 8 sites were analyzed for toxic metals and cesium-137. With three important exceptions, concentrations of chlorinated contaminants and toxic metals were similar to or lower than those in Europe. Cesium-137 was not detected in any samples. The exceptions were localized contamination with the most toxic dioxin congener, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and generalized contamination with beta-hexachlorocyclohexane and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDT). The localized high concentrations of TCDD (range 6.2 to 118.2 pg/g fat) are the highest documented in the world in a population currently of reproductive age. Calculated incremental lifetime excess cancer risk to an infant exposed to these high concentrations of TCDD range from 28 to 82 x 10(-5). Based in part on the results of this study, the Ministry of Health is promoting breast feeding. However, possible adverse developmental effects associated with both prenatal and postnatal (through breast milk) TCDD exposure have not been adequately assessed. Further epidemiologic research is needed to examine these effects in this newly identified high-risk population.

The comparative trial of TCu 380A IUD and progesterone-releasing vaginal ring used by lactating women

The objective of this paper was to compare the efficacy, acceptability, safety, and bleeding pattern of TCu 380A intrauterine device (IUD) and progesterone-releasing vaginal ring used by breastfeeding women. The study population included 97 breastfeeding women using IUD and 100 women using vaginal ring. Of the IUD users, no insertion failure, perforation, or accidental pregnancy occurred in 12 months. There was one IUD expulsion. There were no discontinuations of IUD due to medical reasons other than expulsion. The total discontinuation rate was 2.3%. In the ring group, no accidental pregnancy occurred. The major reasons for discontinuation were ring use-related problems and vaginal problems. The total discontinuation rate was 65.4% within 1 year. The frequency of any one complaint among the ring users was higher than that among the IUD users. There were no differences in the proportion of women having no sexual activity and in the weight of their babies between the two groups. Compared with the IUD users, the median number of bleeding/spotting (B/S) episodes and B/S days of the vaginal ring users were fewer; consequently, the mean length of B/S-free interval was longer in all four reference periods; the mean length of B/S episode and segment were the same; the occurrence of amenorrhea was more frequent; in contrast, the proportions of normal bleeding patterns were fewer. The frequencies of prolonged bleeding, frequent bleeding, and infrequent bleeding patterns did not differ between the two groups. The percentage of irregular bleeding was fewer only in the first two reference periods. It is concluded that the TCu 380A IUD and progesterone-releasing vaginal ring used by breastfeeding women are safe and effective. The higher discontinuation rate of the ring users was mainly because of use-related problems. Breastfeeding women with TCu 380A IUD had better tolerance and acceptability. The TCu 380A IUD does not, but the progesterone-releasing vaginal ring does, suppress the recovery of ovarian function. However, once return of menstruation occurred, there were no differences in bleeding patterns between the two contraceptive methods.

Lipid content and essential fatty acid (EFA) composition of mature Congolese breast milk are influenced by mothers' nutritional status: impact on infants' EFA supply

OBJECTIVE

To measure the lipid content and the fatty acid (FA) composition of breast milk as part of a nutritional survey of the essential fatty acid (EFA) status of 5 months old Congolese infants.

DESIGN

Cross sectional nutrition survey.

SETTING

A suburban district of Brazzaville (capital of the Congo).

SUBJECTS

A random sample of nursing mothers and their 5 months old infants (n = 102). Data collection procedures: The mothers were questioned on their socio-economic status, dietary habits, and their body mass index (BMI) was measured. Breast milk samples were collected from each mother. Milk lipid content and fatty acid composition were determined.

RESULTS

Compared with milk from various countries, Congolese women's mature breast milk was low in lipid (28.70+/-11.33 g/L) but rich in 8:0-14:0 FAs (25.97+/-8.17% of total FAs) and in polyunsaturated FAs (PUFAs), particularly n-3 PUFAs (2.39+/-0.68% of total FAs, mainly 18:3 and 22:6). This was associated with the frequent consumption of high-carbohydrate foods (processed cassava roots, wheat bread, doughnuts) known to enhance 8:0-14:0 FA biosynthesis, and with that of foods providing n-6 and n-3 EFAs such as freshwater and saltwater fish, vegetable oil, green leafy vegetables, and high-fat fruit (peanuts, avocado, bushbutter). These foods were traditionally and locally produced. Milk lipid content was negatively related with mothers' BMI (P < 0.01) and varied with the frequency of consumption of certain foods corresponding to distinct dietary patterns.

CONCLUSIONS

Lipid content and FA composition of Congolese breast milk were dependent on mother's nutritional status. However, despite an adequate EFA composition of breast milk, partially breast-fed 5 months old Congolese infants probably did not get enough n-6 and n-3 EFAs from breast milk to meet their EFA requirements.

Increased muscular efficiency during lactation in Colombian women

OBJECTIVE

To determine the muscular efficiency of lactating women and compare it to that of nonpregnant, nonlactating (NPNL) women.

DESIGN

The study was retrospective. The subjects were selected randomly in the two groups and studied on three occasions (rounds) separated by approximately three months.

SUBJECTS

There were 109, 101, and 80 NPNL women and 45, 31 and 16 lactating women in rounds 1, 2 and 3 respectively, 19-43 y of age, living under economically deprived conditions in Cali, Colombia, who participated in the study.

METHODS

Muscular efficiency was measured as delta efficiency on a cycle ergometer.

RESULTS

Muscular efficiency was significantly higher in lactating women in all three rounds compared to NPNL women. In six women it was possible to measure efficiency at variable times prior to their pregnancies, and again during lactation about three months post partum. There was a statistically significant (P = 0.03) increase in muscular efficiency during lactation.

CONCLUSION

Lactation results in about a 5% increase in muscular efficiency which may contribute to the adaptation of the mother to the increased energy demands associated with lactation.

Breast milk or animal-product foods improve linear growth of Peruvian toddlers consuming marginal diets

Although breast-feeding is widely accepted as important for infant health, its benefits during the second year of life have been questioned. We analyzed data from 107 breast-fed and weaned Peruvian children living in a periurban community to determine whether breast milk contributed to improved linear growth between 12 and 15 mo of age. Breast-feeding frequency was self-reported; intakes of complementary foods and animal products were estimated from a food-frequency survey. Multivariate-linear-regression analysis was used to predict the length of the children at 15 mo of age. Determinants of length included length and weight-for-length at 12 mo of age (US National Center for Health Statistics standards), interval between 12- and 15-mo measurements, breast-feeding frequency, incidence of diarrhea, and intakes of complementary and animal-product foods. Complementary foods, animal-product foods, and breast milk all promoted toddlers' linear growth. In subjects with low intakes of animal-product foods, breast-feeding was positively associated (P < 0.05) with linear growth. There was a 0.5-cm/3 mo difference in linear growth between weaned toddlers and children who consumed the average number of feedings of breast milk. Linear growth was also positively associated with intake of animal-product foods in children with low intakes of complementary foods. The negative association between diarrhea and linear growth did not occur in subjects with high complementary-food intakes. When the family's diet is low in quality, breast milk is an especially important source of energy, protein, and accompanying micronutrients in young children. Thus, continued breast-feeding after 1 y of age, in conjunction with feeding of complementary foods, should be encouraged in toddlers living in poor circumstances.

Relactation

Relactation may be useful in the developing world either if the child has been ill and unable to feed for a time or the mother is ill or has died. Relactation appears to be easier with a younger infant and in women who have lactated previously. However, with appropriate care, support and motivation even some women who have never been pregnant or who have been pregnant but never lactated may be able to start lactation.

Vitamin B-12 deficiency is very prevalent in lactating Guatemalan women and their infants at three months postpartum

Vitamin B-12 status was evaluated in 113 Guatemalan women and their infants at 3 mo of lactation. Plasma vitamin B-12 was deficient or low in 46.7% of the mothers, and holotranscobalamin II (holo TC II) concentrations were low in 32.3%, which may indicate vitamin B-12 malabsorption. Only 9% had deficient or low plasma folate. Breast milk vitamin B-12 was low in 31%, and negatively correlated with infant urinary methylmalonic acid (UMMA, r = -0.22, P < 0.05, n = 88); UMMA was elevated in 12.2% of the infants, indicating vitamin B-12 deficiency. Mothers of the infants with elevated UMMA had significantly lower concentrations of vitamin B-12 in their breast milk compared with mothers of infants with normal UMMA concentrations (410.7 +/- 247.7 vs. 705.3 +/- 487.5 pmol/L, P = 0.05, n = 87). Mean maternal dietary intake of vitamin B-12 was significantly correlated with plasma vitamin B-12 (r = 0.20, P = 0. 05, n = 94) and was the main determinant of plasma vitamin B-12 in a linear regression model. Determinants of maternal holo TC II concentrations included dietary intake of vitamin B-12 and Giardia lamblia infection. There were no statistically significant determinants of infant UMMA concentrations. We conclude that vitamin B-12 deficiency is highly prevalent in these lactating women and is associated with depletion of the vitamin in their infants. The cause of the maternal deficiency is unknown, but malabsorption exacerbated by low dietary intake of the vitamin is a possibility.

Breastfeeding practices in Indonesia

Breastfeeding promotion program was started by the paediatricians and others in 1977, and is becoming a strong activity since 1990 it was declared by the President of the Republic of Indonesia as a National Movement. One year later the First Lady stated the importance of every Indonesian mother to breast-feed her baby, and thereafter many hospitals created the so called "Baby Friendly Hospital". In this occasion we only limit with eminent topics, i.e., "Exclusive Breast-feeding" in Indonesia, and "Breastfeeding amongst Working Mothers." In fact, until now the percentage of mothers who breastfeed exclusively is very low. Although the ever breastfed babies in Indonesia is 97% (Kodyat, 1996) but the data of the "Exclusive Breastfeeding" of Indonesia is just like Pakistan and Thailand, i.e. nearly 2 months, whereas the Philippines and Ceylon showed a figure of 4 months, and India 5 months. The Home Health Survey (SKRT) data in 1992 showed that 63.7% of the babies were exclusively breast-fed until 3 months. Three quarter of the quality of the exclusive breastmilk is quite good, enough or excellent, whereas the other one quarter is poor and this should be interfered by increasing the quality of the breastmilk and/or adding other formula, to prevent the baby of getting "failure to thrive" (Suharyono, 1996). Working mothers use to do "Early Weaning Practices" with very high mixed feeding practices (Matulessy et al, 1996). Mothers have to go to work because they have to support their family income, but unfortunately most of them ignore their main task of care their children.

IN CONCLUSION

the experience in Indonesia proves that a very hard work should still be continued on the effort of promoting breastfeeding, especially regarding the two issues, i.e. "Exclusive breastfeeding" (we do hope at least until 4 months) and the other issue is regarding the "Working Mothers".

Evaluation of biochemical indicators of vitamin A status in breast-feeding and non-breast-feeding Indonesian women

Indicators of vitamin A status were evaluated in nonpregnant breast-feeding (n = 265) and nonpregnant non-breast-feeding (n = 49) Indonesian women. The concentration of vitamin A (not including provitamin A carotenoids) and fat in breast milk was 30% and 20% higher, respectively, for women with a breast-fed child 7-18 mo old than for women with an infant 3-6 mo old. The vitamin A content of milk fat was constant throughout lactation. Breast-milk vitamin A was most sensitive to changes in vitamin A status when expressed per volume. Sensitivity and specificity for detecting serum retinol concentrations < 0.70 mumol/L were < 75% for the concentration of breast-milk vitamin A and serum retinol binding protein (RBP). The modified-relative-dose-response (MRDR) method suffers from a relatively large intraindividual variation in the ratio of dehydroretinol to retinol because of vulnerability of the dehydroretinol concentration to laboratory errors and to variation in dosing and absorption. Within categories of dehydroretinol:retinol, serum retinol concentration was lower in breast-feeding women than in non-breast-feeding women. Thus, it may be necessary to use different cutoff values for the ratio and for serum retinol concentration. Serum retinol concentration, which was just above marginal (0.85 mumol/L), had the smallest within-person variation and was also the most sensitive indicator for detecting a difference between groups in change in vitamin A status postintervention, requiring only 19 subjects per group. Serum RBP concentration, breast-milk vitamin A expressed per volume or per gram milk fat, and the MRDR method required groups of 35, 36, 139, and 53 subjects, respectively.

Non-puerperal induced lactation in a Nigerian community: case reports

Six Nigerian women aged from 22 to 56 years who had not recently been pregnant were successfully relactated by breast suckling alone. All of them produced enough milk to exclusively breastfeed 'motherless' infants. All except one child have continued to breastfeed up to the time of this report and show adequate growth.

Regression analysis of the effect of full and partial lactation on post-partum amenorrhoea in lower middle class Indian females

This study presents a simple regression analysis of the impact of full and partial breast feeding on post-partum amenorrhoea (PPA) in lower middle class Indian women. The study has been done on a sample of hospital based data collected in 1992. The analysis shows a highly significant correlation. Further, the impact of lactation on PPA was notably less in case with partial breast feeding as compared to those with full breast feeding.

Premature introduction of progestin-only contraceptive methods during lactation

Experts on contraceptive technology concur that progestin-only methods can be used safely during lactation. However, very few studies exist of the effects on lactation of the introduction of progestin-only methods prior to the sixth postpartum week. Since progesterone withdrawal is the likely stimulus that initiates lactogenesis, it appears necessary for natural progesterone levels to decline to baseline before a progestin-only contraceptive is initiated. Therefore, the use of such contraceptive methods should be delayed for at least 3 days after the birth. Non-hormonal methods remain the first choice category of contraceptive methods for breastfeeding women, since there is no possibility that they will interfere with lactation. Progestin-only methods comprise a viable and often desirable next choice category, although the timing of their commencement must be determined with care in order to support lactation.

Lactational performance of adolescent mothers shows preliminary differences from that of adult women

PURPOSE

The purposes of this study were to characterize milk production, milk composition, and the lactational behavior of adolescent mothers, and to compare their lactational performance with that of adult females.

METHODS

Twenty-two lactating mothers, 11 adolescents and 11 adults, were studied at 6-week intervals between 6 and 24 weeks postpartum. Milk production was determined by the test-weighing procedure. Milk nutrient composition was determined by standard chemical analyses. Frequency and duration of nursing and the use of supplemental formula and complementary foods were recorded.

RESULTS

The amount of milk adolescents produced at 6, 12, 18, and 24 weeks postpartum ranged from 37-54% less (P < .05) than that of the adults and resulted in a 45% weaning rate at 18 weeks postpartum in the younger group. Milk nutrient concentrations were not significantly different between groups, with the exception of significantly higher sodium concentrations during early lactation in the adolescents' milk. Lactational behavior differed significantly between the adolescent and adult groups; however, with the exception of the lower frequency of daytime nursing and the tendency toward the early introduction of supplemental formula in the adolescent group, these behavioral differences were the result of the racial and ethnic differences between the two groups. The differences in lactational behavior did not contribute to the differences in milk production between the adolescents and adult mothers.

CONCLUSIONS

This preliminary study suggests that milk production was reduced in adolescent mothers compared with adult females. Although behavioral strategies that increase the frequency of daytime nursing and reduce the frequency of supplemental feedings may enhance the milk production of adolescent mothers, other biological factors may account for their poorer lactational performance.

Effects of oral buserelin on urinary LH secretion in male infants

In recent years, several potent gonadotropin-releasing hormone (GnRH) analogues have become available for female contraception and one of them (buserelin) has been tested in lactating women. However, the possible effects on infants due to the transference of the analogue through breast milk have not been studied. The present work evaluated the effect of oral buserelin on urinary LH secretion in male infants. A total of 19 healthy full-term boys (aged 2-4 months) were included in the study. Infants received orally a single dose of a GnRH agonist mixed with breast milk. Urine samples were collected prior to, and 4-6 and 24 h after treatment for LH measurement. The results disclosed a significant increase in LH urine level in the sample taken 4-6 h after buserelin administration. Twenty-four hours after GnRH agonist ingestion, the LH level returned to baseline level. The present study demonstrated that GnRH analogue administered orally to infants escapes from gastrointestinal inactivation and induces a significant rise in LH levels 4-6 h after treatment.

Contraceptives for lactating women: a comparative trial of a progesterone-releasing vaginal ring and the copper T 380A IUD

From approximately one week before normal ovulation resumes, lactating women require protection against pregnancy by a contraceptive that is safe for both infant and mother in a multicenter one-year study, the natural hormone, progesterone, delivered vaginally by a sequence of four contraceptive rings designed for continuous use, was evaluated as a contraceptive for nursing mothers in comparison with the Copper T 380A IUD. Individual rings release in effective average dose of 10 mg day for a 3 month period. Evaluation included measures of lactational performance as well as of contraceptive efficacy and safety to mother and child. Nine participating clinics enrolled 802 ring users and 734 IUD acceptors between postpartum days 29 and 63. Life table analyses were performed with parallel decrements for ring and IUD subjects. Continuation in the study and analysis required that subjects not stop breastfeeding. The ring, with a one-year pregnancy rate of 1.5 per 100, did not differ significantly from the IUD with respect to contraceptive effectiveness (p > 0.05). More than half of the ring subjects were continuing at 6 months post admission and a quarter (23.5 per hundred) were still using the ring and breastfeeding one year after admission. Women with the IUD, however, had higher continuation rates (p < 0.001) at both time points. The largest single decrement for each method was that for weaning. Ring users had more complaints of vaginal problems but had fewer vaginal disorders on examination. At 12 months postpartum, 46 per 100 continuing ring users remained in amenorrhea. Lactation performance and the health and weight gain of the infants were similar among users of either regimen.

Total energy expenditure and physical activity level of lactating Mesoamerindians

Energy-sparing mechanisms may be elicited to meet increased energy requirements imposed by lactation on women who reside in poor, rural communities in developing countries. The objectives of this study were to measure total energy expenditure and its components, basal and activity energy expenditure, and to investigate their relationships with lactation performance in a total of 40 rural Mesoamerindians stratified according to postpartum body mass index. Total energy expenditure and fat-free mass were measured by the doubly labeled water method, and basal metabolic rate was determined by indirect calorimetry at 3 and 6 mo postpartum. Physical activity level was taken as the ratio of total energy expenditure to basal metabolic rate. Milk energy output, which is not included in total energy expenditure, was computed from 24-h milk intake (test-weighing) and energy concentration of milk (bomb calorimetry). Anthropometric measurements revealed negligible mobilization of tissue stores. Mean (+/- SD) total energy expenditures were 8912 +/- 1296 kJ/d and 9253 +/- 1298 kJ/d for the lower and higher body mass index groups, respectively. Adjusted for fat-free mass, total energy expenditure was higher in the lower body mass index group (P = 0.05). Adjusted for fat-free mass, basal metabolic rate did not differ between groups. Physical activity level was significantly higher in the lower body mass index group (P = 0.03). Lactation performance did not differ between groups and was not associated with total energy expenditure or its components. Despite the maintenance of energy balance and heightened energy requirements of lactation, energy-sparing mechanisms were not evident in these lactating Mesoamerindians.