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Biomedical subjects

R H Gray

Publications and source records attributed to R H Gray.

At least 73 records · Page 4Linked to original sources
PubMed1997

Adverse outcomes of planned and unplanned pregnancies among users of natural family planning: a prospective study.

OBJECTIVES: The purpose of this study was to determine prospectively whether unplanned pregnancies are associated with adverse pregnancy outcomes among users of natural family planning. METHODS: Women who became pregnant while using natural family planning were identified in five centers worldwide: there were 373 unplanned and 367 planned pregnancies in this cohort. The subjects were followed up at 16 and 32 weeks' gestation and after delivery. The risks of spontaneous abortion, low birth-weight, and preterm birth were estimated after adjustment by logistic regression. RESULTS: The women with unplanned pregnancies were more likely to be at the extremes of age, to report more medical problems before and during the index pregnancy, and to seek antenatal care later in gestation than the women with planned pregnancies. However, women with planned pregnancies reported a higher rate of spontaneous abortion in previous pregnancies (28.8%) than did women with unplanned pregnancies (12.9%). There were no significant differences in the rates of spontaneous abortion, low birthweight, or preterm birth between the two groups. CONCLUSIONS: No increased risk of adverse pregnancy outcomes was observed among women who experienced an unplanned pregnancy while using natural family planning.

Abortion, Spontaneous↗
PubMed1996

Ethylene glycol ethers and risks of spontaneous abortion and subfertility.

Potential reproductive effects from occupational exposures to ethylene glycol ethers (EGE) are of concern since these organic solvents have been used widely in industry, and their reproductive toxicity has been well documented in animal studies. For determination of whether occupational exposure to EGE was associated with increased risks of spontaneous abortion and subfertility (i.e., taking more than 1 year of unprotected intercourse to conceive), a retrospective cohort study was conducted among workers at two semiconductor manufacturing plants in the eastern United States in 1980-1989 as part of a larger evaluation of reproductive health. Reproductive and occupational histories were obtained from interviews of semiconductor manufacturing workers and spouses. Assessment of potential exposure to mixtures containing EGE (none, low, medium, and high) was based on reported processes and company records. There were 1,150 pregnancies to semiconductor manufacturers, 561 to female employees and 589 to wives of male employees. Among female manufacturers, potential exposure to mixtures containing EGE was associated with increased risks of spontaneous abortion (relative risk in the high exposure group = 2.8; 95% confidence interval (CI) 1.4-5.6) and subfertility (odds ratio in the high exposure group = 4.6; 95% CI 1.6-13.3). Both of these risks exhibited a dose-response relation with potential EGE exposure (p for trend = 0.02). Among spouses of male manufacturers potentially exposed to mixtures containing EGE, there was no increased risk of spontaneous abortion, but there was a nonsignificant increased risk of subfertility (odds ratio in the high exposure group = 1.7; 95% CI 0.7-4.3).

Abortion, Spontaneous↗
PubMed1996

Further evidence that infection is an infrequent cause of first trimester spontaneous abortion.

A previous cohort study found no clinical evidence that infection occurred more often in subjects experiencing pregnancy loss compared with those experiencing successful pregnancy [Simpson et al. (1996) Hum. Reprod., 11, 668-672]. Given these surprising findings, we conducted a similar analysis on another cohort also followed prospectively. Using couples practising natural family planning for conception or contraception, information on clinical evidence of infection was gathered beginning with week 5 of gestation. Information on fever and signs of overt infection was specifically sought by interview and physical examination. Frequencies of urinary, vaginal and other infections in subjects experiencing pregnancy loss were 11.1, 9.5 and 8.7% respectively, not significantly different from rates in subjects having liveborns (10.1, 10.2 and 10.3% respectively). Thus, no association between clinical infection and early pregnancy loss (< or = 16 weeks) was observed. Cohort studies utilizing biologically based assays are awaited because extant data do not provide evidence that clinically evident infections play major roles in first trimester pregnancy losses.

Abortion, Spontaneous↗
PubMed1996

Demographic survey of the level and determinants of perinatal mortality in Karachi, Pakistan.

A demographic survey was used to estimate the level and determinants of perinatal mortality in eight lower socio-economic squatter settlements of Karachi, Pakistan. The perinatal mortality rate was 54.1 per 1000 births, with a stillbirth to early neonatal mortality ratio of 1:1. About 65% of neonatal deaths occurred in the early neonatal period, and early neonatal mortality contributed 32% of all infant deaths. Risk factor assessment was conducted on 375 perinatal deaths and 6070 current survivors. Poorer socio-economic status variables such as maternal and paternal illiteracy, maternal work outside the home and fewer household assets were significantly associated with perinatal mortality as were biological factors of higher parental age, short birth intervals and poor obstetric history. Multivariable logistic analysis indicated that some socio-economic factors retained their significance after adjusting for the more proximate biological factors. Population attributable risk estimates suggest that public health measures for screening of high-risk women and use of family planning to space births will not improve perinatal mortality substantially without improvement of socio-economic conditions, particularly maternal education. The results of this study indicate that an evaluation of perinatal mortality can be conducted using pregnancy histories derived from demographic surveys.

Adolescent↗
PubMed1995

Effects of caffeine consumption on delayed conception.

The authors examined the effects of caffeine consumption on waiting time to conception in the Reproductive Health Study, a retrospective study of 1,430 non-contracepting, parous women interviewed between July 1989 and June 1990 at Fishkill, New York, and Burlington, Vermont. Information was obtained on 2,501 pregnancies since 1980. Women's reported consumption of caffeinated beverages during the first month of pregnancy was used to estimate daily caffeine intake, which was categorized as none, 1-150, 151-300, and > or = 301 mg. Information on delayed conception was analyzed as a dichotomous variable (< or = 12 months delay vs. > 12 months delay), and the per cycle probability of conception (fecundability) was estimated using waiting time to conception as a continuous variable. Odds ratios of delayed conception and fecundability ratios adjusted for age, parity, smoking, last contraceptive used, infertility history, and race, were estimated by logistic regression and Cox proportional hazard models, respectively. Women who did not smoke and who consumed no caffeine were used as a reference group. The adjusted odds ratio of delayed conception for more than one year was not increased among women who consumed < or = 300 mg of caffeine daily. However, the odds ratio (OR) was 2.65 (95% confidence interval (CI) 1.38-5.07) among nonsmokers who consumed > or = 301 mg of caffeine daily. Although smoking per se was associated with a significant increased risk of delayed conception (OR = 1.77, 95% CI 1.33-2.37), no effect of high caffeine consumption was observed among women who smoked. Fecundability was reduced among nonsmokers who consumed more than 300 mg caffeine daily (fecundability ratio = 0.74, 95% CI 0.59-0.92). Smoking reduced the fecundability ratio, but the authors observed no effect of caffeine consumption on fecundability among women who smoked. Other studies provide biologic plausibility for these findings. The authors conclude that high levels of caffeine consumption may result in delayed conception among women who do not smoke cigarettes.

Adult↗
PubMed1995

Infertility and early pregnancy loss.

OBJECTIVES: We describe the epidemiologic characteristics of conception, including subclinical early pregnancy loss, in a population of healthy women volunteers who had heterogeneous fertility experiences, and we describe the conception experience of women within this group who had evidence of impaired fertility. STUDY DESIGN: This was a prospective observational study of a cohort of women employed in two semiconductor manufacturing facilities. A total of 148 volunteers completed interviews and daily diaries and collected daily urine specimens for an average of 7 months. Conception, including subclinical losses and clinical pregnancies, was determined with a highly sensitive and specific assay for urinary human chorionic gonadotropin, and ovulation was determined with assays of urinary ovarian steroid hormones. RESULTS: There were 679 menstrual cycles at risk for pregnancy contributed by 124 (84%) of the 148 women. Women with evidence of subfertility before or during the study period had a rate of early pregnancy loss of 70% compared with 21% in women without fertility problems (relative risk 2.6, 95% confidence interval 1.8 to 3.8). The risk of pregnancy loss associated with subfertility increased with age and remained the same in women treated with clomiphene citrate. CONCLUSIONS: These results suggest that subfertile women have increased subclinical pregnancy losses regardless of fertility treatment and that the association between reduced fertility and advancing age may be related, in part, to early subclinical pregnancy loss.

Abortion, Spontaneous↗
PubMed1995

Timing of conception and the risk of spontaneous abortion among pregnancies occurring during the use of natural family planning.

OBJECTIVE: Our purpose was to ascertain the effects of timing of conception on the risk of spontaneous abortion. STUDY DESIGN: To assess these effects, women who conceived while using natural family planning were identified in five centers worldwide between 1987 and 1993. Timing of conception was determined from 868 natural family planning charts that recorded day of intercourse and indices of ovulation (cervical mucus peak obtained according to the ovulation method and/or basal body temperature). Conceptions on days - 1 or 0 with respect to the natural family planning estimated day of ovulation were considered to be "optimally timed," and all other conceptions were considered as "non-optimally timed." The rate of spontaneous abortions per 100 pregnancies was examined in relation to timing of conception, ages, reproductive history, and other covariates with bivariate and multivariate statistical methods. RESULTS: There were 88 spontaneous abortions among 868 pregnancies (10.1%). The spontaneous abortion rate was similar for 361 optimally timed conceptions (9.1%) and 507 non-optimally timed conceptions (10.9%). However, among 171 women who had experienced a spontaneous abortion in a prior pregnancy, the rate of spontaneous abortion in the index pregnancy was significantly higher with non-optimally timed conceptions (22.6%) as compared with optimally timed conceptions (7.3%). This association was not observed among 697 women with no history of pregnancy loss. The adjusted relative risk of spontaneous abortion among women with non-optimally timed conceptions and a history of pregnancy loss was 2.35 (95% confidence intervals 1.42 to 3.89). The excess risk of spontaneous abortion was observed with both preovulatory and postovulatory conceptions. CONCLUSIONS: Overall, there is no excess risk of spontaneous abortion among the pregnancies conceived during natural family planning use. However, among women with a history of pregnancy loss, there is an increased risk of spontaneous abortion associated with preovulatory or postovulatory delayed conceptions.

Abortion, Spontaneous↗
PubMed1995

The social dynamics of HIV transmission as reflected through discordant couples in rural Uganda.

OBJECTIVE: To describe the role of men and women as sources of HIV transmission and to estimate HIV incidence among discordant couples resident in diverse rural communities in Uganda. SETTING: Rakai, a rural district in Uganda, East Africa. METHODS: A population-based cohort study, which has been conducted as annual serological and behavioral surveys since 1989. Community clusters were stratified into trading centers on main roads, intermediate trading villages on secondary roads and agricultural villages off roads. In the 1990 survey round, serological data were available for 79 discordant and 411 concordant HIV-negative couples aged 13-49 years. The present analysis examines sex-specific seropositivity associated with place of residence and the incidence of seroconversion among discordant couples between 1990 and 1991. RESULTS: Seventy-nine discordant couples were followed; the HIV-positive partner was male in 44 couples (57%) and female in 35 couples (43%). There was marked variation in the sex of the seropositive partner by place of residence: women were the HIV-positive partner in 57% of couples from trading centers, 52% from intermediate villages, and 20% from agricultural communities (P < 0.008). Condom use was higher in discordant couples in which the man was the uninfected partner (17.1%) rather than the woman (9.5%). HIV-positive women, but not HIV-positive men, reported significantly more sexual partners and more genital ulcers than seronegative individuals of the same sex. Seroincidence rates among men and women in discordant relationship were 8.7 and 9.2 per 100 person-years (PY), respectively, which was much higher than in concordant seronegative couples (men, 0.82; women, 0.87 per 100 PY). CONCLUSIONS: In this Ugandan population, men are the predominant source of new infections in rural villages. Risk factors and preventive behaviors vary with the sex of the infected partner, and seroconversion rates are similar in both sexes.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Distribution and determinants of low birthweight in central Sudan.

Two studies were conducted during 1989-90 in Central Sudan to determine the incidence of low birthweight and to ascertain the major risk factors which influence birthweight. In a hospital-based investigation, surveillance of all births was accompanied by a nested case-control study, and in a community based investigation, all midwife-assisted births were studied. There were 4868 and 1523 livebirths among the hospital and community populations, respectively. The incidence of low birthweight was 18.1% in the community and 8.2% in the hospitals. The ratio of term to pre-term low birthweight was 2.9 in the community but only 1.3 in the hospitals. Several risk factors showed consistent and significant associations with low birthweight in the hospital and community studies. Two important and modifiable predictors of term and preterm low birthweight were low maternal weight and malaria infection during pregnancy. Other risk factors included low socio-economic status and, among the hospital population, lack of antenatal care, short birth intervals, poor obstetric history and complications of pregnancy.

Case-Control Studies↗
PubMed1994

Incidence of HIV-1 infection in a rural region of Uganda.

OBJECTIVE: To determine the incidence of infection with HIV-1 and the risk factors associated with seroconversion in three geographical strata of a rural Ugandan district. DESIGN: Serological, sociodemographic, and behavioural surveys of everyone aged 13 or more in 21 randomly selected communities at baseline and one year later. SETTING: Rural population of Rakai district, southwestern Uganda, residing in main road trading centres, secondary trading villages, and agricultural villages. SUBJECTS: In 1989, 1292 adults provided a blood sample and interview data; one year later, 778 survivors (77%) who had been seronegative at baseline provided follow up data. MAIN OUTCOME MEASURES: Incidence of HIV infection in relation to individual characteristics and risk factors, including place of residence. RESULTS: Incidence of HIV infection in all adults was 2.1/100 person years of observation (SE 0.5 (95% confidence interval 1.1 to 3.1)); in people aged 15-39 the incidence was 3.2/100 person years. Incidence was highest in men and women aged 20-24 (9.2/100 person years (3.9) and 6.8/100 person years (2.9) respectively). Risk factors significantly associated with seroconversion were age 24 and under and two or more sexual partners. Between the surveys the proportion of all respondents reporting high risk behaviour (two or more partners) significantly increased from 8.9% to 12.3%. CONCLUSIONS: Despite preventive programmes and substantial knowledge about AIDS the incidence of HIV infection remains high in this rural population. Prevention aimed at vulnerable rural communities is urgently needed to contain the HIV epidemic.

Adolescent↗
PubMed1994

Levels and determinants of perinatal mortality in central Sudan.

OBJECTIVES: To determine levels and risk factors for perinatal mortality in Central Sudan. METHODS: Hospital and community based studies were conducted during the period 1989-1990. Of 5328 births registered in the hospital, 197 stillborns and 812 live-born infants were included in a nested case-control study. In the community, a follow-up study was conducted on 1592 midwife-assisted home deliveries. Multivariate logistic regression analysis was used to identify predictors of perinatal mortality and adjusted population attributable risks were estimated to assess the contribution of each factor. RESULTS: The perinatal mortality rate was 85.4/1000 births in the hospital population and 29.4/1000 births in the community population. The major risk factors for perinatal mortality in the hospital and the community studies were similar and modifiable. CONCLUSIONS: To lower perinatal mortality, improvements in maternal nutrition, malaria treatment and control, avoidance of agricultural pesticides during pregnancy, and adequate antenatal and intrapartum care are recommended.

Case-Control Studies↗
PubMed1994

A community-based nested case-control study of maternal mortality.

OBJECTIVES: Population-based information from Pakistan on maternal mortality is inadequate to define the magnitude of the problem or to contribute information on the distribution of clinical causes and risk factors. A population-based survey was conducted in eight urban squatter settlements of Karachi, Pakistan, to address these key issues. METHODS: Pre-coded questionnaires were administered to the 10,135 households to ascertain deaths of household members in the 5 years preceding the survey (1984-1989). A verbal autopsy questionnaire was administered to the 121 households where a female death between 15 and 49 years of age was reported. RESULTS: The maternal mortality ratio was estimated as 281 per 100,000 livebirths with hemorrhage, eclampsia and puerperal sepsis as the major causes of maternal deaths. Important risk factors identified were maternal employment, paternal unemployment, and poor prior pregnancy history. Women did seek health care but the assistance sought was often inappropriate. CONCLUSION: Intervention programs for improving timely referral and upgrading of hospitals are suggested.

Adolescent↗