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D D Baird

Publications and source records attributed to D D Baird.

At least 37 records · Page 2Linked to original sources
PubMed1999

Time of implantation of the conceptus and loss of pregnancy.

BACKGROUND: Implantation of the conceptus is a key step in pregnancy, but little is known about the time of implantation or the relation between the time of implantation and the outcome of pregnancy. METHODS: We collected daily urine samples for up to six months from 221 women attempting to conceive after ceasing to use contraception. Ovulation was identified on the basis of the ratio of urinary estrogen metabolites to progesterone metabolites, which changes rapidly with luteinization of the ovarian follicle. The time of implantation was defined by the appearance of chorionic gonadotropin in maternal urine. RESULTS: There were 199 conceptions, for 95 percent of which (189) we had sufficient data for analysis. Of these 189 pregnancies, 141 (75 percent) lasted at least six weeks past the last menstrual period, and the remaining 48 pregnancies (25 percent) ended in early loss. Among the pregnancies that lasted six weeks or more, the first appearance of chorionic gonadotropin occurred 6 to 12 days after ovulation; 118 women (84 percent) had implantation on day 8, 9, or 10. The risk of early pregnancy loss increased with later implantation (P<0.001). Among the 102 conceptuses that implanted by the ninth day, 13 percent ended in early loss. This proportion rose to 26 percent with implantation on day 10, to 52 percent on day 11, and to 82 percent after day 11. CONCLUSIONS: In most successful human pregnancies, the conceptus implants 8 to 10 days after ovulation. The risk of early pregnancy loss increases with later implantation.

Abortion, Spontaneous↗
PubMed1999

Preimplantation urinary hormone profiles and the probability of conception in healthy women.

OBJECTIVE: To examine hormonal predictors of conception in menstrual cycles from normal women. DESIGN: Longitudinal study. SETTING: Community. PATIENT(S): Two hundred fifteen healthy female volunteers with no known fertility problems who were trying to conceive. INTERVENTION(S): Participants recorded menstrual bleeding, sexual intercourse, and collected first morning urine specimens daily from when they stopped contraception until they became pregnant or for 6 months if no clinical pregnancy was achieved. Measurements were made of urinary LH and urinary metabolites of estrogen and progesterone. MAIN OUTCOME MEASURE(S): Conception was identified by a sensitive and specific immunoradiometric assay for urinary hCG. RESULT(S): Statistical analyses of 189 conception and 409 nonconception cycles controlled for sexual intercourse and interdependence of cycles from the same woman. Conception was more likely in cycles with lower baseline progesterone metabolite levels, higher ovulatory LH, and higher midluteal progesterone. Midluteal estrogen also was elevated in conception cycles when examined without adjusting for other hormone levels, but this finding did not persist after multivariate adjustment. CONCLUSIONS: Menstrual cycles in normal women vary in their hormonal quality in ways that are predictive of cycle fertility.

Adult↗
PubMed1999

Physical activity at age 12 and adult breast cancer risk (United States).

OBJECTIVES: Some epidemiologic studies suggest that adolescent physical activity reduces subsequent breast cancer risk. To examine this question further, we analyzed data on physical activity at age 12 that had been collected as part of the Carolina Breast Cancer Study (CBCS). METHODS: The CBCS is a population-based, case-control study of 527 white and 337 African-American cases and 790 controls, frequency-matched on age and race. Respondents were asked whether, and to what extent, they engaged in four specific activities at age 12 (walking to school, biking to school, competitive training, performing vigorous household chores). RESULTS: Women who reported participation in any of the four activities had a modest reduction in breast cancer risk (odds ratio (OR): 0.8, 95% confidence interval (CI): 0.6-1.0). Using an index measuring approximate number of activity episodes per week, analyses revealed modest inverse relationships for nearly all levels of activity relative to no reported activity; a weighting of the index by metabolic equivalent scores produced similar results. CONCLUSIONS: Our findings support the hypothesis that adolescent physical activity may protect against adult breast cancer, even at moderate levels.

Adolescent↗
PubMed1999

Day-specific probabilities of clinical pregnancy based on two studies with imperfect measures of ovulation.

Two studies have related the timing of sexual intercourse (relative to ovulation) to day-specific fecundability. The first was a study of Catholic couples practising natural family planning in London in the 1950s and 1960s and the second was of North Carolina couples attempting to become pregnant in the early 1980s. The former identified ovulation based on the ovulatory shift in the basal body temperature, while the latter used urinary assays of hormones. We use a statistical model to correct for error in identifying ovulation and to re-estimate the length of the fertile window and day-specific fecundabilities. We estimate the same 6-day fertile interval in both studies after controlling for error. After adjusting for error both data sets showed the highest estimate of the probability of pregnancy on the day prior to ovulation and both fell close to zero after ovulation. Given that the fertile interval is before ovulation, methods that anticipate ovulation by several days (such as the assessment of cervical mucus) would be particularly useful for couples who want to time their intercourse either to avoid or facilitate conception.

Adult↗
PubMed1999

Adolescent reproductive events and subsequent breast cancer risk.

OBJECTIVES: This study investigated the relationship between reproductive events during adolescence and subsequent breast cancer risk. METHODS: Logistic regression models used self-reported data from 862 case patients and 790 controls in the Carolina Breast Cancer Study. RESULTS: Miscarriage, induced abortion, and full-term pregnancy before 20 years of age were not associated with breast cancer. Among premenopausal women, breast-feeding before 20 years of age was inversely associated with disease. Oral contraceptive use before 18 years of age was positively associated with disease risk among African American women only. CONCLUSIONS: Pregnancy during adolescence does not appear to influence breast cancer risk, but breast-feeding may. A possible increased breast cancer risk among African American women who used oral contraceptives as adolescents warrants further study.

Adolescent↗
PubMed1999

Menstrual and reproductive risk factors for ischemic heart disease.

The role of hormones in ischemic heart disease is of considerable interest, but limited data are available pertaining to risk factors associated with endogenous hormones. We examined the association between menstrual and reproductive factors and ischemic heart disease in a cohort of 867 white, college-educated women who prospectively recorded menstrual cycle data for at least 5 years from their early 20s through their menopause. Ischemic heart disease history was obtained from a self-administered (N = 714) or proxy-administered (N = 153) questionnaire completed at a mean age of 73 years. The analysis included 44,899 person-years of follow-up and 45 cases of myocardial infarction, angioplasty, heart bypass surgery, or ischemic heart disease-related mortality. Ischemic heart disease risk decreased with increasing age at menarche (age-adjusted RR 0.76 per year, 95% CI = 0.60-0.95). Considering menstrual cycle characteristics ages 28-32, there was little overall association with length, variability, or bleeding duration. Ischemic heart disease risk increased with later age at first birth (age-adjusted RR 2.90 for ages 33-43 compared with 25-29) and later age at last birth (age-adjusted RR 3.79 for ages > or =40 compared with 35-39), but there was little association with high parity.

Age Distribution↗
PubMed1998

Post-ovulatory ageing of the human oocyte and embryo failure.

We carried out a prospective study of 221 healthy women who were attempting pregnancy. During the study, women collected daily urine samples and kept daily records of intercourse. Ovulation and early pregnancy losses were later identified by immunoassays of urinary human chorionic gonadotrophin and steroid metabolites. We have used these data to examine whether the risk of early pregnancy loss was higher with post-ovulatory ageing of the oocyte. 192 pregnancies were ranked by the probability that the oocyte might have aged before fertilization. There was a statistically significant increase in the risk of early loss as the likelihood of oocyte ageing increased (P < 0.05). No similar risk was observed for clinical miscarriages. Post-ovulatory ageing of the oocyte prior to fertilization may cause early pregnancy failure in humans as it does in several other mammalian species.

Adult↗
PubMed1997

Time to pregnancy and preterm delivery.

OBJECTIVE: To test whether subfertile women may be at higher risk of preterm delivery. METHODS: We used data from two population-based cohort studies on risk factors and pregnancy outcome for approximately 20,000 deliveries in three major Danish obstetric departments. The Aalborg-Odense study comprised all pregnant women attending routine antenatal care at two obstetric departments from 1984 to 1987. In all, 11,850 women (86%) filled in a questionnaire at about 36 weeks' gestation. The Aarhus study addressed women at the routine visit near 16 weeks' gestation from 1989 to 1991; a study questionnaire was returned by 6857 (80%). Both studies excluded women with chronic illnesses, multiple fetuses, and inability to speak Danish. Only women with planned pregnancies were included in the analysis. In all, 8855 and 3985 women from Aalborg-Odense and Aarhus, respectively, were eligible for the analyses. In both cohorts, women were categorized according to their waiting time to pregnancy (0-6 months, 7-12 months, and greater than 1 year) and according to examination or treatment for infertility (yes, no). Preterm delivery was defined as birth before 37 completed weeks. RESULTS: Compared with women who tried for 6 months or less before they conceived, women who tried for 7-12 months had 1.3 times (95% confidence interval [CI] 0.8, 2.1) the adjusted risk of preterm delivery in both cohorts, and women with a time to pregnancy of greater than 12 months had adjusted relative risks for preterm delivery of 1.6 (95% CI 1.1, 2.2) for Aalborg-Odense and 1.7 (95% CI 1.1, 2.6) for Aarhus. The results remained similar after excluding women with infertility treatment. CONCLUSIONS: Pregnant women with subfertility and clinically defined infertility are more prone to preterm delivery, even in the absence of infertility treatment.

Adult↗
PubMed1997

Preimplantation hormonal differences between the conception and non-conception menstrual cycles of 32 normal women.

We compared daily urinary concentrations of oestrogen and progesterone metabolites in paired menstrual cycles (conception and non-conception) from 32 women. Volunteers with no known fertility problems were enrolled in the study at the time they began trying to become pregnant. They collected first-morning urine specimens and kept daily records of menstrual bleeding and sexual intercourse for 6 months or until they became clinically pregnant. Intercourse in non-conception cycles was close to the time of ovulation so that failure to conceive was caused by factors other than poorly timed intercourse. Compared with non-conception cycles, conception cycles had a steeper early luteal rise in progesterone and higher mid-luteal oestrogen and progesterone concentrations. These hormonal characteristics may be markers of better quality cycles, but because all these differences were in the luteal phase, we cannot rule out the possibility that the preimplantation embryo had stimulated early increases in steroid production. We propose an analysis strategy that could help support or refute the importance of preimplantation embryonic signalling, but our small sample size limits our own conclusions about this mechanism.

Adult↗
PubMed1997

Breast cancer survival and the timing of tumor removal during the menstrual cycle.

In a retrospective cohort study of 262 premenopausal breast cancer patients treated at the Mayo Clinic between 1965 and 1985, we investigated whether survival was associated with the timing of tumor removal during the menstrual cycle. Participants were women < or = 50 years old who had not used exogenous hormones, been pregnant, been lactating, or given birth within 6 months of diagnosis. The menstrual cycle day at surgery was used to assign women to group 1 (cycle days 0-7), group 2 (cycle days 8-15), or group 3 (after cycle day 15). Cox proportional hazards analysis adjusting for age at diagnosis, stage, tumor size, grade, and node involvement showed a nonsignificantly worse survival for group 2 than for group 3 [hazard ratio (HR), 1.41; 95% confidence interval (CI), 0.89-2.23]. Stratification revealed that the association between survival and timing of tumor removal during the menstrual cycle was slightly stronger among patients with stage II disease (adjusted HR, 1.56; 95% CI, 0.92-2.63). The association was the same among patients with stage II disease and node involvement (adjusted HR, 1.57; 95% CI, 0.82-3.03). Prospective studies using hormone measurements to define menstrual cycle status more accurately than the reported day of the menstrual cycle could provide further insight about the postulated association.

Adult↗
PubMed1996

Self-reported allergy, infection, and autoimmune diseases among men and women exposed in utero to diethylstilbestrol.

Immunotoxicology studies of prenatal or neonatal exposure to diethylstilbestrol (DES) show effects on immune function of the adult animal. Prenatally exposed humans are known to be at increased risk of vaginal adenocarcinoma, but little research has been done to assess immunologic function. A placebo-controlled clinical trial of DES was conducted in the early 1950s. The sons and daughters born to participants of this clinical trial were traced and interviewed about immune-related health problems. Symptom and disease rates for the DES exposed (253 sons and 296 daughters) were compared with rates for the unexposed (241 men and 246 women). DES-exposed men and women reported rates of allergy, infection, and autoimmune disease similar to the unexposed. However, because autoimmune diseases are rare, a larger sample is needed to evaluate further DES-associated risk of autoimmunity.

Adult↗
PubMed1996

Ethylene oxide exposure may increase the risk of spontaneous abortion, preterm birth, and postterm birth.

Ethylene oxide is a gas used in some dental offices to sterilize equipment. In pregnant laboratory animals, ethylene oxide increases malformations and feral loss. Increased gestation length has also been reported. In humans, two studies have reported increased spontaneous abortions among ethylene oxide-exposed women, but few other data exist. We sent questionnaires to 7,000 dental assistants, age 18-39 years, registered in California in 1987; 4,856 responded (69%). We based our analysis on 1,320 women whose most recent pregnancy was conceived while working full-time. Thirty-two women reported exposure to ethylene oxide; unexposed dental assistants comprised the comparison group. We estimated relative risks of spontaneous abortion and preterm birth using a person-week model. We estimated relative risks of postterm birth (> or = 42 weeks) and a combined adverse outcomes model using logistic regression. Among exposed women, the age-adjusted relative risk of spontaneous abortion was 2.5 [95% confidence interval (CI) = 1.0-6.3], for preterm birth 2.7 (95% CI = 0.8-8.8), and for postterm birth 2.1 (95% CI = 0.7-5.9). The estimated relative risk of any of these adverse outcomes among exposed women was 2.5 (95% CI = 1.0-6.1) after adjusting for age, nitrous oxide, and number of mercury amalgams prepared. These data further implicate ethylene oxide as a possible reproductive toxicant in humans.

Abortion, Spontaneous↗
PubMed1996

Vaginal douching and reduced fertility.

OBJECTIVES: This study investigated douching and reduced fertility. METHODS: The monthly probability of conception for douchers and nondouchers was compared in a sample of 840 married, parous women in King County, Washington. Data on the number of months required to conceive were analyzed. RESULTS: In comparison with nondouchers, women who douched were 30% less likely to become pregnant each month they attempted pregnancy. This relationship remained after adjustment for covariates, and it could not be explained by women douching for medical reasons. The reduction was not related to the type of douching preparation used. Young women who douched had significantly greater reductions in monthly fertility than older women (50% reduction for women 18 to 24 years old, 29% reduction for women 25 to 29 years old, and 6% reduction for women 30 to 39 years old). CONCLUSIONS: Douching was associated with reduced fertility. Further research is needed to determine whether the relationship is casual and, if so, to what extent it is mediated by pelvic infection. In the meantime, women should be informed that douching may have adverse effects.

Adolescent↗
PubMed1995

Timing of sexual intercourse in relation to ovulation. Effects on the probability of conception, survival of the pregnancy, and sex of the baby.

BACKGROUND: The timing of sexual intercourse in relation to ovulation strongly influences the chance of conception, although the actual number of fertile days in a woman's menstrual cycle is uncertain. The timing of intercourse may also be associated with the sex of the baby. METHODS: We recruited 221 healthy women who were planning to become pregnant. At the same time the women stopped using birth-control methods, they began collecting daily urine specimens and keeping daily records of whether they had sexual intercourse. We measured estrogen and progesterone metabolites in urine to estimate the day of ovulation. RESULTS: In a total of 625 menstrual cycles for which the dates of ovulation could be estimated, 192 pregnancies were initiated, as indicated by increases in the urinary concentration of human chorionic gonadotropin around the expected time of implantation. Two thirds (n = 129) ended in live births. Conception occurred only when intercourse took place during a six-day period that ended on the estimated day of ovulation. The probability of conception ranged from 0.10 when intercourse occurred five days before ovulation to 0.33 when it occurred on the day of ovulation itself. There was no evident relation between the age of sperm and the viability of the conceptus, although only 6 percent of the pregnancies could be firmly attributed to sperm that were three or more days old. Cycles producing male and female babies had similar patterns of intercourse in relation to ovulation. CONCLUSIONS: Among healthy women trying to conceive, nearly all pregnancies can be attributed to intercourse during a six-day period ending on the day of ovulation. For practical purposes, the timing of sexual intercourse in relation to ovulation has no influence on the sex of the baby.

Adult↗