Characteristics of human ovulation in natural cycles correlated with age and achievement of pregnancy

Ovulation patterns affect the offspring sex ratios and change with the women's age

Background

The aim of this study was to evaluate whether women’s ages at conception and the ratio of male to female infants are associated with various ovulation patterns.

Methods

An observational clinical study was conducted in private OB/GYN clinics. Infertile women with regular menstrual cycles receiving intrauterine insemination (IUI) and/or in-vitro fertilization (IVF) had their ovulation patterns monitored in three consecutive spontaneous cycles receiving infertility treatment in the third cycle. Ovulation patterns were also observed in women with slight ovulation disorders during IUI and/or IVF in clomiphene citrate stimulated cycles. All the pregnant women’s ages at conception and their respective offspring sex ratios were compared to various ovulation patterns. Statistical evaluation was performed using ANOVA, unpaired t test, χ² test or Fisher’s exact test, heterogeneity χ² test, odds ratios at 95% confidence intervals and logistic regression.

Results

Contralateral ovulation (i.e. ovulation jumping from ovary to the other) was more often observed in relatively younger women, who showed a higher probability of having a boy than after ipsilateral ovulation. There was a significantly higher frequency of boys being conceived following three consecutive ovulations with a left–left–right (LLR) ovulation pattern, while three ovulations from the left ovary (LLL) were associated with a higher frequency of girls. We also found two consecutive menstrual cycles the left–right (LR) ovulation pattern showed a similar significant difference compared to the left-left (LL) ovulation. Both the infertile and infertile + fertile women groups showing right-sided ovulation, regardless of age, showed significantly higher offspring sex ratio compared to left-sided ovulation, which was not observed in the group of fertile women alone.

Conclusions

LLR, LR and contralateral ovulation happens more often in younger women and favors male offspring in infertile women. Right-sided ovulation favors male offspring in infertile and infertile + fertile women, which was not observed in the group of fertile women.

It is of interest to evaluate whether ovulation patterns change with women’s ages at conception and affect offspring sex ratios. An observational clinical study was conducted in private OB/GYN clinics. Infertile women with regular menstrual cycles receiving intrauterine insemination (IUI) and/or in-vitro fertilization (IVF) had their ovulation patterns monitored in three consecutive spontaneous cycles receiving infertility treatment in the third cycle. Ovulation patterns were also observed in women with slight ovulation disorder during IUI and/or IVF in clomiphene citrate stimulated cycles. Women’s ages and offspring sex ratios were compared to various ovulation patterns. The contralateral ovulation was more often observed in relatively younger women, who showed a higher probability of having a boy than following a pregnancy after ipsilateral ovulation. There was a significantly higher frequency of boys being conceived following three consecutive ovulations with after a left-left-right (LLR) ovulation pattern, while three ovulations from the left ovary (LLL) were associated with a higher frequency of girls. Only considering two consecutive menstrual cycles the left-right (LR) ovulation pattern showed a similar significant difference compared to the left-left (LL) ovulation. Both infertile and infertile + fertile women showing right-sided ovulation, regardless of age, showed significantly higher offspring sex ratio compared to left-sided ovulation, which was not observed in the group of fertile women alone. LLR, LR and contralateral ovulation happens more often in younger women and favor male offspring in infertile women. Right-sided ovulation favors male offspring in infertile and infertile + fertile women, which was not observed in the group of fertile women.

Does an association exist between menstrual cycle length within the normal range and ovarian reserve biomarkers during the reproductive years? A systematic review and meta-analysis

BACKGROUND

Regular menstrual cycling during the reproductive years is an indicator of spontaneous ovulation but sometimes falsely perceived as an indicator of preserved fertility. In contrast, menstrual cycle shortening, a physiologic occurrence preceding the menopausal transition, is not usually perceived as an indicator of decreased ovarian reserve in the general population.

OBJECTIVE AND RATIONALE

The individual decrease in menstrual cycle length (MCL) might represent a sensitive biomarker of diminishing ovarian reserve. The aim of this systematic review and meta-analysis is to examine the possible association between MCL in regularly cycling women (21-35 days) and ovarian reserve tests (ORT), fecundability in natural cycles and IVF outcomes.

SEARCH METHODS

An electronic database search employing PubMed, Web of Science, Trip, EBSCO, ClinicalTrials.gov and the Cochrane library was performed to identify research articles, only on human, published between January 1978 and August 2019. Search terms were pregnancy OR fertility OR fecundity OR fecundability, anti-Müllerian hormone OR AMH OR antral follicle count OR AFC OR ovarian reserve OR ovarian reserve test, in vitro fertilization OR ART OR assisted reproductive therapy OR assisted reproductive treatment OR assisted reproductive technology OR IVF OR ICSI, menstrual cycle length OR menstrual cycle characteristics. We combined these terms to complete the search. All prospective and retrospective studies exploring an association between MCL and proxies of ovarian reserve were included. The exclusions included studies of PCOS, ovarian failure, oral contraception treatment, prior chemotherapy and/or radiotherapy or ovarian surgery. The Newcastle-Ottawa scale was used to assess the quality of studies that were eligible for meta-analysis.

OUTCOMES

Eleven studies were eligible for meta-analysis, including 12 031 women. The included studies had a low risk of bias. Short MCL (21-27 days) was associated with lower ORT values as compared to normal (28-31 days), long (32-35 days) and all other (28-35 days) MCL sets. The estimated weighted mean difference (WMD) of AMH level was -1.3 ng/mL (95% CI: -1.75 to -0.86, P < 0.001) between the short and normal MCL sets. The estimated WMD of AFC values was -5.17 (95% CI: -5.96 to -4.37, P < 0.001) between the short and normal MCL sets. The weighted overall odds ratio (OR) of fecundability in natural cycles between women with short versus normal MCL sets was statistically significant (overall OR 0.81; 95% CI 0.72-0.91, P < 0.001). In the IVF setting, fewer oocytes were retrieved in short MCL in comparison to normal, long and all other MCL sets, with an estimated WMD of -1.8 oocytes (95% CI: -2.5 to -1.1, P < 0.001) in the short versus normal MCL sets. The weighted overall OR of clinical pregnancy rate between women with short versus all other MCL sets was statistically significant (overall OR 0.76; 95% CI: 0.60 to 0.96, P = 0.02). Low levels of heterogeneity were found in most meta-analyses of MCL and qualitative ovarian reserve biomarkers, while heterogeneity was high in meta-analyses performed for quantitative measures.

WIDER IMPLICATIONS

MCL in regularly cycling women is closely related to ovarian reserve biomarkers during the reproductive years. A short MCL, as compared to normal, is significantly associated with lower ORT values, reduced fecundability and inferior IVF outcomes, independent of age. The results imply that short MCL may be a sign of ovarian aging, combining the quantitative and qualitative facets of ovarian reserve. Educational efforts ought to be designed to guide women with short MCL at a young age, who desire children in the future, to seek professional counselling.

Hemorrhagic corpus luteum: Clinical management update

Hemorrhagic corpus luteum (HCL) is an ovarian cyst formed after ovulation and caused by spontaneous bleeding into a corpus luteum (CL) cyst. When HCL rupture happens, a hemoperitoneum results. Clinical symptoms are mainly due to peritoneal irritation by the blood effusion. The differential diagnosis is extensive and standard management is not defined. The authors elaborated a comparison of the differential diagnosis and therapeutic modalities from the laparoscopic approach to nonsurgical, medical options because hemorrhage from HCL is often self-limiting. The authors reviewed all data implicated with the development of HCL, trying to give homogeneity to literature data. The authors analyzed extensive literature data and subdivided the medical approach into many topics. The wait-and-see attitude avoids unnecessary laparoscopic surgery using supportive therapies (antifibrinolytic, analgesics, liquid infusion, transfusions and antibiotic prophylaxis). Surgical therapy: operative management should be laparoscopic, with surgical options such as luteumectomy, ovarian wedge-shaped excision or oophorectomy. Prevention: the possibility to preserve fertility is essential, mainly in patients with bleeding disorders or undergoing anticoagulant therapy; therefore, they need estro-progestinics or GnRH analogues to prevent ovulation and avoid further episodes of HCL. This review will aid physicians in making an early diagnosis of HCL, to avoid unnecessary surgery, and use the most effective treatment.

Metformin Abrogates Age-Associated Ovarian Fibrosis

PURPOSE

The ovarian cancer risk factors of age and ovulation are curious because ovarian cancer incidence increases in postmenopausal women, long after ovulations have ceased. To determine how age and ovulation underlie ovarian cancer risk, we assessed the effects of these risk factors on the ovarian microenvironment.

EXPERIMENTAL DESIGN

Aged C57/lcrfa mice (0-33 months old) were generated to assess the aged ovarian microenvironment. To expand our findings into human aging, we assembled a cohort of normal human ovaries (n = 18, 21-71 years old). To validate our findings, an independent cohort of normal human ovaries was assembled (n = 9, 41-82 years old).

RESULTS

We first validated the presence of age-associated murine ovarian fibrosis. Using interdisciplinary methodologies, we provide novel evidence that ovarian fibrosis also develops in human postmenopausal ovaries across two independent cohorts (n = 27). Fibrotic ovaries have an increased CD206⁺:CD68⁺ cell ratio, CD8⁺ T-cell infiltration, and profibrotic DPP4⁺αSMA⁺ fibroblasts. Metformin use was associated with attenuated CD8⁺ T-cell infiltration and reduced CD206⁺:CD68⁺ cell ratio.

CONCLUSIONS

These data support a novel hypothesis that unifies the primary nonhereditary ovarian cancer risk factors through the development of ovarian fibrosis and the formation of a premetastatic niche, and suggests a potential use for metformin in ovarian cancer prophylaxis.See related commentary by Madariaga et al., p. 523.

Left-Right Asymmetry of Tubal Pregnancy: A 12-Year Retrospective Hospital-Based Study

STUDY OBJECTIVE

To investigate whether there are left-right asymmetries, factors affecting lateral dominance, and clinical feature differences in the left and right sides of tubal pregnancy (TP).

DESIGN

Retrospective study (Canadian Task Force classification II-2).

SETTING

International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University.

PATIENTS

Patients (n = 6186) with TP treated surgically.

INTERVENTIONS

We used data from the digital medical records system of the hospital. Women diagnosed with ectopic pregnancy(EP) between January 2005 and December 2016 in the inpatient department of gynecology were included. All data from the medical files were obtained retrospectively, including demographic characteristics; reproductive, gynecologic, and surgical history; clinical features; and treatment. Patients who were previously treated by salpingectomy or nonsurgical management and those with unknown-site EP or non-TPs were excluded.

MEASUREMENTS AND MAIN RESULTS

The overall frequency of right-sided TP was 54.48% (3370/6186), which is significantly higher than 50% (p < .001, binominal test). The proportion of right-sided TPs decreased with age (p for trend = .007) and from the proximal (interstitial) end to the distal (fimbrial) end of the tube (p for trend = .017). Of the TP patients with a corpus luteum, we found the corpus luteum was more frequently located in the right ovary (p < .001) and in the contralateral ovary to the TP side in 41.38% of cases. However, tubal rupture was more frequent in left TP than the in right TP (p = .005).

CONCLUSION

The left-right asymmetries of TP include right-side dominance and the clinical feature differences between the 2sides of TP.

Left-right differences in ovarian volume and antral follicle count in 1423 women of reproductive age

The aim of this cross-sectional study was to investigate side differences in antral follicle count (AFC) and ovarian volume in left versus right ovaries in relation to chronological and "biological" age, the latter estimated by anti-Müllerian hormone (AMH) levels. The cohort comprised 1423 women: 1014 fertile and 409 infertile. All were examined by transvaginal sonography and serum AMH. Overall the right ovary contained 8.1% more antral follicles (p = 0.002) and had 10.7% larger volume compared with the left (p < 0.001). In all AMH quartiles, the right ovarian volume was larger than the left (p ≤ 0.003). AFC was significantly higher in the right compared to the left ovary in the three upper AMH quartiles (p ≤ 0.005). The findings were similar when stratified in age quartiles. More than half (54.8%) had polycystic ovarian (PCO) morphology in at least one ovary. Of these women, 46.3% (n = 361) had PCO morphology unilateral - most frequently on the right side (27.6%) compared to the left (18.7%, p < 0.001). The consistent difference in AFC and ovarian volume found in AMH and age quartiles may be explained by presence of a larger pool of primordial follicles in the right ovary established during fetal life.

Gonadotropin releasing hormone antagonist administration for treatment of early type severe ovarian hyperstimulation syndrome: a case series

Objective

To report an efficacy of gonadotropin releasing hormone (GnRH) antagonist administration after freezing of all embryos for treatment of early type ovarian hyperstimulation syndrome (OHSS).

Methods

In 10 women who developed fulminant early type OHSS after freezing of all embryos, GnRH antagonist (cetrorelix 0.25 mg per day) was started at the time of hospitalization and continued for 2 to 4 days. Fluid therapy and drainage of ascites was performed as usual.

Results

Early type OHSS was successfully treated without any complication. At hospitalization, the median (95% confidence interval [CI]) of the right and the left ovarian diameter was 10.0 cm (7.6 to 12.9 cm) and 8.5 cm (7.5 to 12.6 cm). After completion of GnRH antagonist administration, it was decreased to 7.4 cm (6.2 to 10.7 cm) (P=0.028) and 7.8 cm (5.7 to 12.2 cm) (P=0.116), respectively. The median duration of hospital stay was 6 days (3 to 11 days). Trans-abdominal drainage of ascites was performed in 2 women and drainage of ascites by percutaneous indwelling catheter was performed in 4 women. No side effect of GnRH antagonist was noted.

Conclusion

GnRH antagonist administration appears to be safe and effective for women with fulminant early type OHSS after freezing all embryos. Optimal dose or duration of GnRH antagonist should be further determined.

Urinary follicle-stimulating hormone as a measure of natural fertility in a community cohort

High serum follicle-stimulating hormone (FSH) levels have been associated with diminished ovarian reserve; however, the association between high urinary FSH and reduced natural fertility has yet to be established. We sought to characterize the relationship between a single or multiple measurements of early follicular phase urinary FSH and fertility. Women (n = 209), 30 to 44 years old with no history of infertility, who had been trying to conceive for less than 3 months, provided early follicular phase urine. Participants subsequently kept a diary to record bleeding and intercourse and conducted standardized pregnancy testing for up to 6 months. A subset of women (N = 95) collected urine on cycle day 3 for up to 6 cycles. Urine was analyzed for FSH and creatinine (cr) corrected. Proportional hazard models were used to calculate fecundability ratios (FRs). Urinary FSH levels across cycles from the same woman were highly correlated (adjusted intraclass correlation = .77); within-woman variance was 3-fold lower than variance among women. Women with an initial urinary FSH level <7 mIU/mg cr exhibited a nonsignificant reduction in the probability of pregnancy (adjusted FR 0.71, 95% confidence interval [CI]: 0.45-1.13), as did women with elevated urinary FSH (≥12 mIU/mg cr; adjusted FR 0.78, 95% CI: 0.46-1.32). Using the most recent or maximum urinary FSH value did not strengthen the association. In the general population, urinary FSH levels appear to be nonlinearly associated with fertility; however, broad CIs indicate a lack of statistical significance. Repetitive testing appears to be of little benefit.

The laterality of ovulation: how far does it matter?

The laterality of ovulation, or the side at which ovulation occurs, was the subject of much research in the past century, but it was discussed merely as an interesting physiologic issue in all primates. In the last few years, the increasing development of infertility treatment has drawn the attention of researchers to the clinical aspects of this phenomenon. In the review, we discuss the nature of ovulation side and how far it can influence pregnancy outcome in infertile women treated with different modalities.

Women with one ovary in assisted reproduction technologies: a review of the literature

BACKGROUND

A number of patients who have undergone assisted reproductive technology (ART) have only one ovary.

PURPOSE

This article reviews the clinical implications of the absence of an ovary on the reproductive potential and the outcome in ART cycle.

DATA SOURCES

MEDLINE, Pubmed, the Cochrane Controlled Trials Register, and Cochrane Database of Systematic Reviews from the 1980s through April 2010.

STUDY SELECTION

Randomized, controlled trials; systematic reviews of trials; and observational studies; all restricted to English-language articles.

DATA SYNTHESIS

This review includes 58 articles. Women with a single ovary did not, in general, respond as well to ovulation induction treatment than women with two ovaries in ART cycles. It appears however, that once women with a single ovary achieve the stage of embryo transfer, they can be reassured that their chances of having a child are the same as women with two ovaries. Whether the right or left ovary responds better to superovulation is a question which remains unanswered in the literature.

LIMITATIONS

The authors could not address all management questions, and excluded non-English-language literature.

Symmetry in number of retrieved oocytes between two ovaries: a possible predictor of in vitro fertilization outcome

OBJECTIVE

To examine the relationship between the ratio of difference in number of retrieved oocytes from the two ovaries to total number of oocytes (difference ratio, |N(RO) - N(LO)|/N(TOTAL)) and in?vitro fertilization (IVF) outcome.

METHODS

Retrospective review of medical record for infertility patients with intact two ovaries who had undertaken controlled ovarian stimulation (COS) and IVF cycles in Seoul National University Hospital was conducted. Characteristics and IVF outcomes were compared according to the difference ratio (|N(RO) - N(LO)|/N(TOTAL)) using student t-test and χ² test. To adjust for the effect of confounding factors, binary logistic regression test was performed.

RESULTS

When the study population was divided according to the difference ratio by cut-off value of 0.4, patients with difference ratio less than 0.4 showed significantly higher pregnancy rate (25.7% vs. 17.1%, p = 0.021). A significant correlation was noted between the difference ratio and achievement of pregnancy after adjustment for patient's age and total number of top quality embryos transferred (adjusted OR = 0.40, 95% CI 0.19-0.83, p = 0.014).

CONCLUSIONS

The difference ratio of retrieved oocytes in patients with intact two ovaries was observed to have prognostic value in IVF cycles.

A prospective cohort study of menstrual characteristics and time to pregnancy

The authors examined the association between menstrual characteristics and time to pregnancy among 2,653 Danish women enrolled in a prospective cohort study (2007-2009). Menstrual characteristics were reported at baseline. Outcome data were updated bimonthly until pregnancy, fertility treatment, loss to follow-up, or end of observation (12 cycles). Adjusted fecundability ratios and 95% confidence intervals were estimated by using discrete-time Cox regression models. Relative to average cycle lengths (27-29 days), fecundability ratios for cycle lengths <25, 25-26, 30-31, 32-33, and ≥34 days were 0.64 (95% confidence interval (CI): 0.49, 0.84), 0.94 (95% CI: 0.77, 1.13), 1.10 (95% CI: 0.97, 1.25), 1.35 (95% CI: 1.06, 1.73), and 1.17 (95% CI: 0.91, 1.49), respectively. Compared with cycles that regularized within 2 years after menarche, fecundability ratios for cycles that regularized 2-3 and ≥4 years after menarche were 0.90 (95% CI: 0.80, 1.02) and 0.89 (95% CI: 0.77, 1.03), respectively. Fecundability ratios were 0.87 (95% CI: 0.72, 1.05) comparing <3 with 3-4 days of menstrual bleeding and 0.70 (95% CI: 0.43, 1.13) comparing very heavy with moderate flow. In the present study, shorter cycle length was associated with delayed time to pregnancy. Age at menarche, time to menstrual regularization, and duration or intensity of menstrual flow were not appreciably associated with fecundability.

Clinical implications of ovarian reserve testing

Serum and urinary markers of ovarian reserve, follicular phase inhibin B, follicle stimulating hormone, and antimullerian hormone levels, are physiologically associated with ovarian aging, decline with chronologic age, and appear to predict later stages of reproductive aging including the menopause transition and menopause. In infertile women, they can be used to predict low oocyte yield and treatment failure in women undergoing in vitro fertilization. These markers seem to be affected by common ovarian toxicants, such as smoking, which advance the age at menopause. Although available for commercial use, home test kits have not been shown to predict fertility or infertility in the general population. Clinical use of these markers is limited by the variety of assays, lack of definitive thresholds, and their intercycle variability in older women. Results should be conveyed with caution when highly discrepant with age, in the obese, and in women with irregular menstrual cycles. Further research is needed to assess their predictive value for determining fertility in the general population.

Fetal size in the second trimester is associated with the duration of pregnancy, small fetuses having longer pregnancies

Background

Conventionally, the pregnancy duration is accepted to be 280–282 days. Fetuses determined by ultrasound biometry to be small in early pregnancy, have an increased risk of premature birth. We speculate that the higher rate of preterm delivery in such small fetuses represents a pathological outcome not applicable to physiological pregnancies. Here we test the hypothesis that in low-risk pregnancies fetal growth (expressed by fetal size in the second trimester) is itself a determinant for pregnancy duration with the slower growing fetuses having a longer pregnancy.

Methods

We analysed duration of gestation data for 541 women who had a spontaneous delivery having previously been recruited to a cross-sectional study of 650 low-risk pregnancies. All had a regular menses and a known date of their last menstrual period (LMP). Subjects were examined using ultrasound to determine fetal head circumference (HC), abdominal circumference (AC) and femur length (FL) at 10–24 weeks of gestation. Length of the pregnancy was calculated from LMP, and birth weights were noted. The effect of fetal size at 10–24 weeks of gestation on pregnancy duration was assessed also when adjusting for the difference between LMP and ultrasound based fetal age.

Results

Small fetuses (z-score -2.5) at second trimester ultrasound scan had lower birth weights (p < 0.0001) and longer duration of pregnancy (p < 0.0001) than large fetuses (z-score +2.5): 289.6 days (95%CI 288.0 to 291.1) vs. 276.1 (95%CI 273.6 to 278.4) for HC, 289.0 days (95%CI 287.4 to 290.6) vs. 276.9 days (95%CI 274.4 to 279.2) for AC and 288.3 vs. 277.9 days (95%CI 275.6 to 280.1) for FL. Controlling for the difference between LMP and ultrasound dating (using HC measurement), the effect of fetal size on pregnancy length was reduced to half but was still present for AC and FL (comparing z-score -2.5 with +2.5, 286.6 vs. 280.2 days, p = 0.004, and 286.0 vs. 280.9, p = 0.008, respectively).

Conclusion

Fetal size in the second trimester is a determinant of birth weight and pregnancy duration, small fetuses having lower birth weights and longer pregnancies (up to 13 days compared with large fetuses). Our results support a concept of individually assigned pregnancy duration according to growth rates rather than imposing a standard of 280–282 days on all pregnancies.

Lifestyle and reproductive factors associated with follicular phase length

PURPOSE

Variability in menstrual cycle length, largely determined by variation in follicular phase length, is related to several health outcomes, yet the causes of this variability are incompletely understood. We sought to identify characteristics associated with follicular phase length.

METHODS

We used the North Carolina Early Pregnancy Study to describe factors correlated with timing of ovulation (follicular phase length). Women collected daily urine specimens and recorded vaginal bleeding. Specimens were assayed for estrone 3-glucuronide and pregnanediol 3-glucuronide, which in turn were used to estimate the day of ovulation. All other variables were assessed through interview. Associations with follicular phase length were evaluated using a multiple regression model.

RESULTS

We determined follicular phase length for the first cycles of 201 women. Women with a history of miscarriage tended to have shorter follicular phases (2.2 days). Longer duration of oral contraceptive (OC) use and recent OC use (in the last 90 days) were both correlated with longer follicular phase. Occasional marijuana users (up to three times in the last 3 months) had a longer follicular phase than nonusers (3.5 days); the follicular phase in frequent users (more than three times) was almost 2 days longer than that of nonusers.

CONCLUSIONS

The association between marijuana use and longer follicular phase is consistent with prior rhesus monkey research that shows ovulatory delay or inhibition.

Deeply infiltrating endometriosis: pathogenetic implications of the anatomical distribution

BACKGROUND

To investigate whether knowledge of the anatomical distribution of histologically proven deeply infiltrating endometriosis (DIE) lesions contributes to understanding the pathogenesis.

METHODS

Observational study between June 1992 and December 2004 (retrospective study between 1992 and 2000; prospective study between 2001 and 2004). Continuous series of 426 patients suffering from pelvic pain who underwent complete surgical exeresis of DIE. DIE lesions were classified according to four different possibilities: (i) Firstly, DIE lesions were classified as located in the anterior or posterior pelvic compartment. (ii) Secondly, DIE were classified as left, median and right. (iii) Thirdly, DIE lesions were classified as pelvic or abdominal. (iv) Fourthly, DIE lesions that could present in a right and/or left location were classified as unilateral or bilateral.

RESULTS

These 426 patients presented 759 histologically proven DIE lesions: bladder (48 lesions; 6.3%); uterosacral (USL) (400 lesions; 52.7%); vagina (123 lesions; 16.2%); ureter (16 lesions; 2.1%) and intestine (172, 22.7%). DIE lesions are significantly more often located in the pelvis (n=730 lesions) than in the abdomen (n=29 lesions) (P<0.0001). Pelvic DIE lesions are significantly more often located in the posterior compartment of the pelvis [682 DIE lesions (93.4%) versus 48 DIE lesions (6.6%); P<0.0001]. Pelvic DIE lesions are significantly more frequently located on the left side. For patients with unilateral pelvic DIE lesions, the anatomical distribution is significantly different in the three groups: left (172 lesions; 32.0%), median (284 lesions; 52.8%) and right (82 lesions; 15.2%) (P<0.0001). For patients with lateral lesions, left DIE lesions (172 lesions; 67.8%) were found significantly more frequently than right DIE lesions (82 lesions; 32.2%) (P<0.0001). A similar predisposition was observed when we included patients with bilateral pelvic DIE lesions (P=0.0031). The same significantly asymmetric distribution is observed for total (pelvic and abdominal) DIE lesions.

CONCLUSIONS

Our results demonstrate that distribution of DIE lesions is asymmetric. It is possible that this is related to the anatomical difference between the left and right hemipelvis and to the flow of peritoneal fluid. These findings support the hypothesis that retrograde menstruation of regurgitated endometrial cells is implicated in the pathogenesis of DIE.

Menstrual cycle characteristics: associations with fertility and spontaneous abortion

BACKGROUND

Epidemiologists often use menstrual cycle patterns as indicators of endocrine function in environmental and occupational studies, yet few studies have considered whether menstrual cycle characteristics are associated with fertility or pregnancy outcome.

METHODS

We prospectively studied 470 women to determine whether cycle length or bleed length were associated with fertility or spontaneous abortion. Women completed daily diaries with information on menstrual bleeding, intercourse, birth control use, and covariates. For each menstrual cycle, women collected at least 2 urine samples, which were assayed for human chorionic gonadotropin to define early pregnancies. Women were followed for 1 year or until the end of a clinical pregnancy.

RESULTS

Cycles with lengths of 30 to 31 days preceded cycles with the highest fecundity. Shorter cycles were less likely to be followed by conception (fecundity ratio [FR] = 0.6; 95% confidence interval [CI] = 0.4-1.0). Compared with 30- to 31-day cycles, conceptions after shorter and longer cycles were more likely to be spontaneously aborted (for shorter cycles, odds ratio [OR] = 3.0 [95% CI = 0.9-9.6] and for longer cycles, OR = 3.0 [0.9-10.6]). Cycles with 5 days of menstrual bleeding had the highest fecundity. Cycles with up to 4 days of bleeding had lower fecundity (for bleed lengths of 4 days, FR = 0.5 [0.3-0.8] and for bleed lengths less than 4 days, FR = 0.6 [0.3-0.9]). Spontaneous abortion was less likely after bleeds greater than 5 days (OR = 0.4 [0.1-1.1]) when compared with 5-day bleeds.

CONCLUSIONS

Menstrual cycle characteristics appear to be associated with fertility and spontaneous abortion.

Ovulation jumping from the left to the right ovary in two successive cycles may increase the chances of pregnancy during intrauterine insemination and/or in vitro fertilization natural cycles

Identification of the ovary from which ovulation takes place in two consecutive menstrual cycles results in one of four ovulation patterns, contralateral and ipsilateral ovulations on the right or on the left ovary. Our data suggest that IVF and IUI treatment in cycles in which development of the dominant follicle occurs in the right-sided ovary--and ovulation took place from the left-sided ovary in the preceding cycle (contralateral right-sided ovulation)--is likely to show the best pregnancy outcome.

Cigarette smoking and effects on hormone function in premenopausal women

Cigarette smoke contains compounds that are suspected to cause reproductive damage and possibly affect hormone activity; therefore, we examined hormone metabolite patterns in relation to validated smoking status. We previously conducted a prospective study of women of reproductive age (n = 403) recruited from a large health maintenance organization, who collected urine daily during an average of three to four menstrual cycles. Data on covariates and daily smoking habits were obtained from a baseline interview and daily diary, and smoking status was validated by cotinine assay. Urinary metabolite levels of estrogen and progesterone were measured daily throughout the cycles. For the present study, we measured urinary levels of the pituitary hormone follicle-stimulating hormone (FSH) in a subset of about 300 menstrual cycles, selected by smoking status, with the time of transition between two cycles being of primary interest. Compared with nonsmokers, moderate to heavy smokers (>/= 10 cigarettes/day) had baseline levels (e.g., early follicular phase) of both steroid metabolites that were 25-35% higher, and heavy smokers (>/= 20 cigarettes/day) had lower luteal-phase progesterone metabolite levels. The mean daily urinary FSH levels around the cycle transition were increased at least 30-35% with moderate smoking, even after adjustment. These patterns suggest that chemicals in tobacco smoke alter endocrine function, perhaps at the level of the ovary, which in turn effects release of the pituitary hormones. This endocrine disruption likely contributes to the reported associations of smoking with adverse reproductive outcomes, including menstrual dysfunction, infertility, and earlier menopause.

Reproductive adaptations to a large-brained fetus open a vulnerability to anovulation similar to polycystic ovary syndrome

During the ovarian or menstrual cycle, prior to ovulation, many female primates exhibit a relatively prolonged follicular phase and terminate the postovulatory luteal phase with menstrual bleeding. The prolonged follicular phase is a trait that distinguishes primate from nonprimate species. It enables extended estrogen-induced proliferation and growth of the uterine endometrium prior to progesterone-induced maturation during the luteal phase to accommodate a potential pregnancy with a rapidly invading placenta. Progressive development of both an extended duration of estrogen-induced, preimplantation endometrial proliferation and a rapidly invading placenta across the Primate order may well have been necessary to accommodate differentiation and growth of an increasingly large fetal brain. Prolongation of the follicular phase in primates has also led to the isolation of the final stages of follicle selection (growth deviation of the dominant follicle from its contemporaries) solely within the follicular phase and thus outside the protection of luteal phase progesterone inhibition of pituitary luteinizing hormone (LH) secretion. Such primate reproductive characteristics put the latter stages of ovarian follicle selection at risk of exposure to excessive pituitary secretion of LH. Excessive secretion of LH during follicle selection could result not only in impaired follicle development, excessive ovarian androgen secretion, and ovulation failure, but also in excessive estrogenic stimulation of the uterine endometrium without intervening menstrual periods. Such reproductive abnormalities are all found in a single, prevalent infertility syndrome afflicting women in their reproductive years: polycystic ovary syndrome (PCOS). We propose that successful female reproductive adaptations to accommodate the growth demands of large-brained primate fetuses have facilitated a particular vulnerability of higher primates to hypergonadotropic disruption of ovulatory function, as found in PCOS.