In-depth analysis of a heterosexually acquired human immunodeficiency virus type 1 superinfection: evolution, temporal fluctuation, and intercompartment dynamics from the seronegative window period through 30 months postinfection

Human immunodeficiency virus type 1 (HIV-1) superinfection refers to the acquisition of another strain by an already infected individual. Here we report a comprehensive genetic analysis of an HIV-1 superinfection acquired heterosexually. The infected individual was in a high-risk cohort in Tanzania, was exposed to multiple subtypes, and was systematically evaluated every 3 months with a fluorescent multi-region genotyping assay. The subject was identified in the window period and was first infected with a complex ACD recombinant strain, became superinfected 6 to 9 months later with an AC recombinant, and was monitored for >2.5 years. The plasma viral load exceeded 400,000 copies/ml during the first 9 months of infection but resolved to the set point of 67,000 copies/ml by 3 months after superinfection; the CD4 cell count was 377 cells/mul at 30 months. Viral diversity was evaluated with techniques designed to fully sample the quasi-species, permitting direct observation of the evolution, temporal fluctuation, and intercompartment dynamics of the initial and superinfecting strains and recombinants derived from them. Within 3 months of superinfection, seven different molecular forms were detected in gag and six were detected in env. The proportions of forms fluctuated widely over time in plasma and peripheral blood mononuclear cells, illustrating how challenging the detection of dually infected individuals can be. Strain-specific nested PCR confirmed that the superinfecting strain was not present until the 9 month follow-up. This study further defines the parameters and dynamics of superinfection and will foster appropriate studies and approaches to gain a more complete understanding of risk factors for superinfection and its impact on clinical progression, epidemiology, and vaccine design.

In-depth, longitudinal analysis of viral quasispecies from an individual triply infected with late-stage human immunodeficiency virus type 1, using a multiple PCR primer approach

Co-infections with more than one human immunodeficiency virus type 1 (HIV-1) subtype appear to be the source of new recombinant strains and may be commonplace in high-risk cohorts exposed to multiple subtypes. Many potential dual infections have been identified during the HIV Superinfection Study in Mbeya, Tanzania, where 600 female bar workers who are highly exposed to subtypes A, C, and D have been evaluated every 3 months for over 3 years by use of the MHAacd HIV-1 genotyping assay. Here we describe an in-depth, longitudinal analysis of the viral quasispecies in a woman who was triply infected with HIV-1 and who developed AIDS and passed away 15 months after enrollment. The MHA results obtained at 0, 3, 6, 9, and 12 months revealed dual-probe reactivities and shifts in subtype over time, indicating a potential dual infection and prompting further investigation. The multiple infection was confirmed by PCR amplification of three genome regions by a multiple primer approach, followed by molecular cloning and sequencing. A highly complex viral quasispecies was found, including several recombinant forms, with vpu/gp120 being the most diverse region. A significant fluctuation in molecular forms over time was observed, showing that the serial sample format is highly desirable, if not essential, for the identification of multiple infections. In a separate experiment, we confirmed that the detection of co-infections is more efficient with the use of multiple amplification primers to overcome the primer bias that results from the enormous diversity in the HIV-1 genome.

HIV-1 subtype E progression among northern Thai couples: traditional and non-traditional predictors of survival

BACKGROUND

In the continuing effort to introduce antiretroviral therapy in resource-limited settings, there is a need to understand differences between natural history of HIV in different populations and to identify feasible clinical measures predictive of survival.

METHODS

We examined predictors of survival among 836 heterosexuals who were infected with HIV subtype CRF01_AE in Thailand.

RESULTS

From 1993 to 1999, 269 (49.4%) men and 65 (25.7%) women died. The median time from the estimated seroconversion to death was 7.8 years (95% confidence interval 7.0-9.1). Men and women with enrolment CD4 counts <200 cells/microl had about 2 and 11 times greater risk of death than those with CD4 counts of 200-500 and >500, respectively. Measurements available in resource-limited settings, including total lymphocyte count (TLC), anaemia, and low body mass index (BMI), also predicted survival. Men with two or more of these predictors had a median survival of 0.8 (0.5-1.8) years, compared with 2.7 (1.9-3.3) years for one predictor and 4.9 (4.1-5.2) years for no predictors.

CONCLUSIONS

The time from HIV infection to death appears shorter among this Thai population than among antiretroviral naive Western populations. CD4 count and viral load (VL) were strong, independent predictors of survival. When CD4 count and VL are unavailable, individuals at high risk for shortened HIV survival may be identified by a combination of low TLC, anaemia, and low BMI. This combination of accessible clinical measures of the disease stage may be useful for medical management in resource-limited settings.

Methamphetamine users in northern Thailand: changing demographics and risks for HIV and STD among treatment-seeking substance abusers

Our objective was to determine sociodemographic, sexual and drug-use-related risk factors among methamphetamine (MA) users presenting for drug treatment in northern Thailand. Patients admitted for drug detoxification for MA and other drugs were studied cross-sectionally for risk factors associated with substance abuse and blood-borne and sexually transmitted pathogens. In all, 1865 (200 women) patients treated for MA, opiate, and mixed substance abuse between 1 February 1999 and 31 January 2000 completed all study procedures. Among 1865 participants, 750 (40.2%) were admitted for MA detoxification and 1115 (59.8%) for opiate (heroin, opium, or both) treatment. MA users were significantly younger, better educated, more likely to be Thai than highland ethnic minorities, and had significantly different sexual risks and sexually transmitted disease rates, including lower syphilis seropositivity and higher chlamydial prevalence, than persons admitted for opiate or mixed drug treatment. For those who reported MA use only, use by injection was rare and HIV infections significantly less common than among all other drug users. Thailand is undergoing an epidemic of MA use. These young users are a strikingly different population from opiate/heroin users in northern Thailand. MA users had higher rates of chlamydia infection than opiate users, reflecting their young age, and HIV rates in this population were lower than injecting drug users, but still elevated. MA use is a serious public health problem in Thailand and both improved prevention and treatment methodologies are urgently needed.

Chronic inflammation with increased human immunodeficiency virus (HIV) RNA expression in the vaginal epithelium of HIV-infected Thai women

Thai residents have a greater risk of heterosexual transmission of human immunodeficiency virus (HIV) than do US residents. To analyze host factors associated with heterosexual transmission, vaginal epithelial biopsies from HIV-seropositive Thai and US women were evaluated for tissue virus load and histologic makeup. In all, 84% of Thai and 14% of US women exhibited a chronic inflammatory T cell infiltrate in the vaginal epithelium. In Thai tissue, the infiltrate was associated with elevated levels of HIV RNA in the epidermis. Uninfected Thai women also had vaginal epithelial inflammation. Inflammation did not correlate with sexually transmitted diseases or HIV disease stage. The higher rates and increased risk of heterosexual transmission in Thailand may be due to chronic inflammation at the site where the virus is transmitted, which leads to the accumulation of activated T cells. Such cells might act as targets for initial viral infection and subsequently as reservoirs that support efficient transmission.

Somatic growth and clinical manifestation in formula fed infants born to HIV--infected mothers during the first year of life

This was a comparative study of the growth and clinical manifestation between infected and uninfected HIV infants both of whom were fed with a limited quantity of powder milk from birth until one year of age. HIV-infected pregnant women were enrolled from the second trimester or the beginning of the third trimester. After birth, infants had physical examinations, body weight and height were recorded at 2, 4, 6, 9 and 12 month visits. All mothers were given 7 kilograms of infant formula at each infant visit until the infant was one year old. Diagnosis for HIV infection in these infants was made by two positive concordant results of DNA PCR or RNA PCR or HIV RNA. One hundred and two infants were diagnosed for HIV status and 21.5 per cent were infected. The infected infants showed signs of malnutrition. From 2-4 months of age, the averages of their weights and heights were lower than those of non-infected infants. Abnormal clinical signs were found in most infected infants by the time they were 9-12 months old. In conclusion for the infants born to HIV- infected mothers, monitoring signs and symptoms including their weight and height from birth till 9-12 months old, is predictive of the infectious status of most infected infants. The administration and management of infant formula in a limited quantity to HIV infected mothers in upper northern provinces of Thailand is possible without causing abnormal infant growth.

Protection against sexually transmitted diseases by granting sex workers in Thailand the choice of using the male or female condom: results from a randomized controlled trial

BACKGROUND

The male condom is the most effective barrier method available for protection against sexually transmitted diseases (STDs), including HIV infection. There is an urgent need to develop and evaluate other prevention methods, such as the female condom. This study estimated the additional protection against STDs offered to sex workers by giving them the option of using the female condom when clients refused to use a male condom.

METHODS

Sex establishments in four cities in Thailand were randomized into two study groups: one in which sex workers were instructed to use male condoms consistently (male condom group); and one in which sex workers had the option of using the female condom if clients refused or were not able to use male condoms (male/female condom group). Randomization was done by sex establishments, and not by individuals, to minimize sharing of female condoms across study groups. The proportion of unprotected sexual acts (defined as sexual acts in which condoms were not used, tore, or slipped in or out) and incidence rate of STDs (gonorrhoea, chlamydial infection, trichomoniasis and genital ulcer disease) were measured over a 24-week period and compared between the two study groups.

FINDINGS

Results are available from 34 sex establishments (249 women) in the male/female condom group, and 37 sex establishments (255 women) in the male condom group. Condom use was very high in both groups (97.9 and 97.3 % of all sexual acts, respectively, P > 0.05). Male condom use was lower in the male/female condom group when compared with the male condom group (88.2 and 97.5%, respectively, P < 0.001). However, this reduction in male condom use was counterbalanced by the use of female condoms in 12.0% of all sexual acts in the male/female condom group, contributing to a 17% reduction in the proportion of unprotected sexual acts in this group when compared to the male condom group (5.9 versus 7.1%, respectively, P = 0.16). Female condom use was sustained over the entire study period. There was also a 24% reduction in the weighted geometric mean incidence rate of STDs in the sex establishments of the male/female condom group compared to the male condom group (2.81 versus 3.69 per 100 person-weeks, P = 0.18).

Reliability of self-reported sexual behavior in human immunodeficiency virus (HIV) concordant and discordant heterosexual couples in northern Thailand

A partner study was conducted in northern Thailand between March 1992 and June 1996 which included data that allowed an assessment of the reliability of self-reports of sexual behavior and contraceptive use among heterosexual couples. The authors enrolled 529 couples among whom all male subjects were human immunodeficiency virus (HIV) seropositive voluntary blood donors and their female sexual partners were either HIV infected (n=246) or HIV seronegative (n=283). The levels of agreement within couples were assessed for recency of last sexual intercourse, sexual activity in the prior year, and contraceptive practices. For HIV discordant couples, a prospective study was conducted to examine risk factors for HIV transmission, the primary goal of the study. This allowed assessment of reliability of inter-partner reports over 6-12 months. Overall, agreement among couples was good for common sexual practices, especially vaginal intercourse and time since last intercourse, but was lower for condom use. Anal and oral sex were infrequently reported by these couples and there was greater disagreement for the occurrence of these practices. Partner agreement for contraceptive histories was good to excellent. Prospective data showed less frequent intercourse and more condom use but reliability remained good. Common sexual practices may be reliable for both HIV concordant and discordant couples in studies estimating prevalent infection. Estimates of incident heterosexually transmitted HIV may be made with greater reliability by studies which include assessment of reports of risk behavior by each member of a couple than studies of individuals.

Risk factors for HIV-1 transmission from HIV-seropositive male blood donors to their regular female partners in northern Thailand

OBJECTIVE

To describe risks for HIV transmission from male blood donors to their regular female sex partners in Chiang Mai, Thailand.

DESIGN

Cross-sectional study.

METHODS

From March 1992 through September 1995, 405 HIV-seropositive male blood donors (index cases) and their regular female partners were enrolled in the study. Women with risk factors for HIV infection other than sexual contact with the index male were excluded. Couples were interviewed and examined; specimens were collected for laboratory analysis.

RESULTS

Overall, 46% of the 405 women enrolled were HIV-positive. Ninety-eight per cent of male index cases had a history of sex with a female prostitute; 1.5% reported always using condoms with their regular partner. History of sexually transmitted disease (STD) and swollen inguinal lymph nodes in the female partner were associated with an increased risk of HIV infection in the female. History in the female of genital herpes [odds ratio (OR), 3.46; 95% confidence interval (CI), 1.50-8.78], gonorrhea or chlamydia infection (OR, 2.71; 95% CI, 1.39-5.53), and stable relationship of longer than 24 months (OR, 2.28; 95% CI, 1.02-5.09) were associated with an increased risk of HIV infection in the female. Consistent condom use in the past 2 years (OR, 0.10; 95% CI, 0.01-0.79) was associated with a decreased risk of HIV infection in the female.

CONCLUSIONS

Married women in northern Thailand who appear otherwise to be at low risk for HIV infection may be exposed to this virus by their husbands. High rates of sex with commercial sex workers among men and low use of condoms within stable relationships may be important factors promoting the transmission of HIV in married couples. Programs to increase the regular use of condoms among married couples could be an important public health intervention to prevent transmission of HIV and other types of STD in northern Thailand.

Multiple condom use in commercial sex in Lamphun Province, Thailand: a community-generated STD/HIV prevention strategy

BACKGROUND AND OBJECTIVE

In an investigation of condom breakage in commercial sex, we found a high proportion of multiple condoms use. This study sought to ascertain the characteristics of brothel-based commercial sex workers (CSWs) and their clients; to identify the decision makers (clients and/or CSWs) active in choosing multiple condom use; and to determine whether there is an implicit hierarchy of condom use negotiation.

GOALS

To identify factors associated with multiple condom use in commercial sex and to provide an understanding of how this innovation developed in this setting.

STUDY DESIGN

Sixty-seven brothel-based CSWs in Lamphun Province who participated in a study of condom breakage participated in a case-control study of multiple versus single condom use, which determined CSW and client characteristics for evidence of multiple condom use. Interviews and focus groups were used to determine decision making for condom use and the contexts for multiple use. Association between characteristics of CSWs/clients and multiple condom use was analyzed using X2 for trend.

RESULTS

No official program encouraged multiple condom use; this appeared to be a community-devised strategy to increase protection from human immunodeficiency virus (HIV) and other sexually transmitted diseases (STDs). CSWs working in daytime brothels had significantly greater multiple condom use than those working in nighttime brothels; mean percentages + SD of multiple simultaneous use were 57.5% + 28.6 and 35.5% + 22.4, respectively (p < 0.001). Day CSWs were older, had more pregnancies, reported higher frequency of STD symptoms and history of pelvic inflammatory disease, and had more clients per day but had a lower number of sex acts per client than night CSWs. Among factors associated with multiple condoms, only age was significant. The decision to use single or multiple condoms for a sex act was primarily (78.2% in single and 79.3% in multiple) made by the CSW herself. The main reason given for multiple condom use was protection from HIV/STD.

CONCLUSIONS

There is high compliance between CSWs in Lamphun province and the Ministry of Public Health-sponsored 100% condom use campaign, and CSWs are attempting to further reduce their risks of HIV/STD exposure by using multiple condoms for sex with their clients.

Sexually transmitted disease prevalence in brothel-based commercial sex workers in Chiang Mai, Thailand: impact of the condom use campaign

One hundred and ninety five (195) brothel-based commercial sex workers (CSW) in Chiang Mai, Thailand, were screened for sexually transmitted disease (STD) between October 1994 and April 1995, prior to their enrollment in a multi-center comparative trial of the effectiveness of two strategies using male and female condoms. These CSW had a mean age of 22.2 (SD 4.3) years. Forty-seven per cent were Thai and 57.4 per cent had no formal education. Median duration of prostitution was 16 months and median cost for sexual service was 50 baht (US$ 2) per client. Ninety-four per cent of CSW reported always using condoms with clients. There were 63 (32.3%) CSW infected with at least one type of the STD screened. The prevalence of STD included chlamydial infection (16.9%), gonococcal infection (14.4%), condyloma accuminata (4.6%), moluscum contagiosum (2.6%) and trichomoniasis (1.0%). There was no statistically significant risk factor for STD found in this study. Despite an active programme for prevention of STD in CSW and the provision of free condoms, STD were diagnosed in one-third of the screened CSW in Chiang Mai. The programme needs to be strengthened by more intensive education and practice in the correct and consistent use of condoms and integrated with other STD prevention programmes.

Multiple condom use and decreased condom breakage and slippage in Thailand

There is compelling evidence that male condoms effectively prevent transmission of sexual pathogens, including HIV-1. Condom breakage and slippage reduce this effect. We measured rates of condom slippage and breakage during heterosexual commercial sex in northern Thailand. Of 7,594 condoms examined in 4,734 client visits (5,040 sex acts), breakage was noted in 1.8% of single condom use (49.3% of acts), as compared with 0.2% with two condoms (49% of sex acts), and no breaks with more than two condoms (1.2% of sex acts). These breakage rates declined from 5.9% in a similar 1992 study in which 2.8% of sex acts were with more than one condom used at a time. Slippage occurred in only 0.1% of sex acts. Case-control analysis indicated that multiple clients, younger aged clients, sex after midnight, and high intensity (rough) sex were associated with condom breaks. The decline in breakage may be attributable to greater expertise in condom use by sex workers and clients, in response to the successful Thai national "100% Condom Campaign." Use of more than one condom during sex has been initiated by sex workers and their clients, a community response to condom promotion messages and fears of HIV infection. These data demonstrate the potential of condom use for high efficacy in reducing exposure to HIV-1 and other STDs. If condom use in commercial sex remains high, HIV incidence may decline among Thai men.

Measurement of circulating inhibin forms during the establishment of pregnancy

This study investigated the forms of inhibin released into the circulation 1) in very early pregnancy, 2) after stimulation of the corpus luteum by exogenous hCG, and 3) in abnormal and failing human pregnancy. Samples were assayed by enzyme-linked immunosorbent assays for inhibin A, inhibin B, and inhibin pro-alphaC-related immunoreactivity (pro-alphaC-RI). The concentration of inhibin A rose steadily during the conception luteal phase to an initial peak 12 days after ovulation (104 +/- 23 pg/mL), then rose rapidly to a further peak 43 days after ovulation 424 +/- 6 pg/mL). The concentration of pro-alphaC-RI exhibited a much larger peak on day 15 after ovulation (1423 +/- 361 pg/mL), but fell thereafter. The concentration of inhibin B was low after ovulation and subsequently barely detectable in pregnancy. hCG treatment resulted in a significant rise in the concentrations of inhibin A and pro-alphaC-RI, but had no effect on the inhibin B concentration. The pro-alphaC-RI concentration was a better indicator of continuing pregnancy viability than either hCG or inhibin A. Early trophoblast secretes proportionately more bioactive inhibin than the corpus luteum. The corpus luteum and trophoblast do not secrete inhibin B into the circulation. These data support the concept of different physiological roles for different inhibin forms.

Nutritional factors and thalassaemia major

Abnormal growth is a common feature of thalassaemia major in children. In an attempt to determine whether it has a nutritional cause, 12 children aged 1 to 3 years with thalassaemia major were studied under metabolic ward conditions. Nutritional status was assessed by anthropometry and biochemistry before and after an intensive nutrition regimen. Five children had wasting or stunting on admission. As a result of the nutrition intervention, mean weight for height improved significantly. The mean height increase of 0.4 cm after one month was not significant. Plasma zinc, depressed in half the children on admission, improved, as did alpha tocopherol, while copper decreased. Plasma insulin-like growth factor-I also increased commensurate with improved growth. Fat absorption was normal in all children. Undernutrition is an important cause of associated growth disturbances in children with thalassaemia major. Malnutrition was primarily caused by inadequate nutrient intake, as indicated by the capacity to gain weight appropriately when provided with nutrition support, and by the absence of intestinal malabsorption. While long term studies are required to determine if nutritional support will prevent stunting, these results underscore its central role in preventing nutritional deficiencies and in promoting normal growth in thalassaemic children.

Condom breakage during commercial sex in Chiang Mai, Thailand

Used condoms in 30 female brothels in Chiang Mai, Thailand, during the period from August 1992 to October 1992 were examined for breakage. Data were also collected by interviewing 326 prostitutes who accounted for 65 percent of the total prostitutes providing condoms. The prostitutes had a mean age of 20.6 +/- 3.2 years. Sixty-one percent had no formal education. The median duration of prostitution was 13 months. The average number of clients per day in the past 24 hours and in the past 3 months was 4.4 +/- 2.5 and 5.5 +/- 2.2, respectively. Eighty-eight percent charged between $2 and less than $8 for their sexual service. All refused to practice oral or anal sex during the past 24 hours. Of 5,559 condoms, 298 were used two at a time and 15 were used three at a time. The breakage rate per act of intercourse was 5.9 percent (95% CI = 5.3, 6.5). The breakage per total condoms examined was 5.7 percent (95% CI = 5.1, 6.3). Breakage relating to manufacturing defect, i.e., pinholes, and that relating to use was 0.8 percent (95% CI = 0.6, 1.0) and 5.0 percent (95% CI = 4.4, 5.6), respectively. The probability of breakage when using two condoms at the same time was 3.4 percent (95% CI = 0.5, 6.3). Most of the breakage occurred at the distal part of the condom. There was no difference between the breakage rates of condoms provided by the brothels and those brought by the client; nor was there any difference between manufacturing defect or use. The breakage rate per client as estimated by prostitutes in the past 24 hours corroborated with that assessed by examination.

The relationship between peripheral immunoactive inhibin, human chorionic gonadotrophin, oestradiol and progesterone during human pregnancy

OBJECTIVE

The objective of this study was to investigate serial changes in the plasma concentration of inhibin in both the very early days of pregnancy following implantation and in late pregnancy. The timing of the changes in inhibin concentration relative to changes in the concentrations of other hormones of pregnancy was also investigated.

DESIGN

Serial observations of the peripheral concentrations of inhibin and other hormones in two groups of healthy volunteers in (a) early pregnancy and (b) late pregnancy.

PATIENTS

(a) Four healthy women recruited on cessation of contraception prior to conception. (b) Nine healthy women recruited at the antenatal clinic.

MEASUREMENTS

In the early pregnancy subjects, the concentrations of inhibin, progesterone, oestradiol and hCG were measured in plasma samples obtained three times per week from day 8 to day 10 of each menstrual cycle until 11 weeks after the last menstrual period in the conception cycle. In the late pregnancy subjects, plasma samples were obtained at 4-week intervals from 12 weeks until term.

RESULTS

The concentration of inhibin, progesterone and oestradiol in conception cycles were similar to those in the preceding cycles until the mid/to late-luteal phase of the cycle when hCG was first measureable. By day 12 of the luteal phase the concentration of inhibin was significantly higher in the pregnancy cycle than in the non-pregnancy cycle (P < 0.05) and progressively increased after the time of the missed menstrual period. The concentration of inhibin reached a peak (513.0 U/l, CI 442.1-595.3) by day 47 when the concentration of hCG was maximal. In early pregnancy the concentration of inhibin was correlated with that of hCG (r = 0.361; P < 0.01) as well as progesterone (r = 0.584, P < 0.001) and oestradiol (r = 0.602, P < 0.001). After 12 weeks there was no significant correlation between hCG and inhibin although significant correlations persisted with progesterone (r = 0.553, P < 0.001) and oestradiol (r = 0.361, P < 0.01).

CONCLUSIONS

The corpus luteum makes a significant contribution to the production of inhibin in early pregnancy while after 12 weeks the placenta is the major source.

Secondary amenorrhea at Maharaj Nakhon Chiang Mai Hospital

One hundred and thirty-seven patients attending the gynaecological endocrine clinic at Maharaj Nakhon Chiang Mai hospital between April 1, 1982 and July 31, 1987 were studied. Detailed history, physical and pelvic examination were obtained on all patients, followed by progesterone withdrawal test and other appropriate laboratory studies including thyroid and reproductive hormone profiles. The most common cause of secondary amenorrhea in this study was hypothalamic-pituitary dysfunction (54.7%), not unlike those reports from other foreign series. However, it was notable that nearly 40 per cent of our patients in this group experienced amenorrhea after discontinuation of contraceptive steroids. Premature ovarian failure was the second leading cause of amenorrhea in our patients (13.9%) and, perhaps, deserve future detailed studies. The other causes of amenorrhea in decreasing frequency were: hyperprolactinemia (11.7%), hypothalamic-pituitary failure (8.0%), Asherman's syndrome (5.1%) and androgen excess (2.9%). Primary hypothyroidism was a rare cause of amenorrhea in this study.

A study of adrenal corticol function and its reserve activity in long-acting injectable contraceptive users

Adrenal function and its reserve capacity were studied in eighteen healthy non-lactating women who received depot-medroxyprogesterone acetate (DMPA: 9 subjects) and norethisterone enanthate (NET-EN: 9 subjects) as long-acting injectable contraceptives. Methodological assessments included: (i) morning fasting concentration of serum cortisol; (ii) diurnal variation of adrenal corticol activity as evidenced by cortisol concentration in serum samples taken at 0700 and 1600 hours; (iii) urinary free cortisol excretion; and (iv) cortisol response to insulin-induced hypoglycaemia. None of these assessments was significantly altered by contraceptive administration. This finding indicates that the subject's ability to release cortisol in response to a stressful situation, as well as to normal day-to-day activity, was not impaired by these contraceptive steroids.

Serum prolactin and cortisol levels after suckling for varying periods of time and the effect of a nipple shield

Plasma prolactin and cortisol levels were measured in mothers breast feeding with or without the use of a thin latex nipple shield, and in mothers wearing a nipple shield but who were not nursing. Suckling duration and milk transfer were also recorded. Suckling duration ranged between 6 and 31 min, being significantly correlated with prolactin levels 40 to 120 min after the feed started. At the latter time, baseline prolactin level and time spent nursing accounted together for most of the variance in prolactin levels: R2 was 0.79 and 0.82 at 90 min and 120 min respectively. Prolactin was released as usual when the shield was in place: levels were not significantly different from levels without the shield. Suckling duration was also unaffected by the shield, but milk transfer was significantly reduced. Cortisol was not released by using the shield, and the shield alone (without suckling) did not release prolactin. The thin latex nipple shield has therefore no untoward effect on the release of these hormones during nursing.