Menstrual cycle characteristics and side of ovulation in the Rhesus monkey

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.

Switching of follicle destiny so that the second largest follicle becomes dominant in monovulatory species

During an ovulatory follicular wave in the monovulatory species of heifers, mares, and women, the two largest follicles deviate in diameter at the end of a common follicle growth phase. The largest follicle before deviation becomes the future ovulatory follicle in most ovulatory waves. In 10-30% of the ovulatory waves, the destiny of the two follicles switches just before or at deviation so that the second-largest follicle becomes the future ovulatory follicle, and the largest follicle becomes a subordinate. In FSH-driven switching in heifers, mares, and women, the wave-stimulating FSH surge decreases to a low concentration before the largest follicle has developed the ability to utilize the low concentrations. The concentrations of FSH then increase (mares, women) or cease to decrease (heifers), and the next largest follicle acquires the capability of becoming the future ovulatory follicle. Luteolysis-driven switching has been reported in heifers but not in mares and women. The switching in heifers occurs during ovulatory wave 3 of three wave interovulatory intervals (IOI) when the wave of follicles is in the common growth phase in synchrony with the time of luteolysis. Regression of the CL during the common growth phase of ovulatory wave 3 is accompanied by decreased activity of follicles that are adjacent to the regressing CL but not when follicles and CL are separated or in opposite ovaries. The role of luteolysis in switching in heifers has been tested by treating with PGF2α when the largest follicle of wave 2 was near the end of the common growth phase. Switching in destiny of the largest follicle from the expected future dominant to a future subordinate occurred in most waves (10 of 17) when the largest follicle and regressing CL were in the same ovary and adjacent but not when separated in the same ovary or when in opposite ovaries (0 of 11). The newly selected future ovulatory follicle may develop in the opposite ovary. Thereby, frequency of the contralateral vs ipsilateral relationship between the preovulatory follicle and CL in heifers is greater in three-wave IOI than in two-wave IOI. In summary, the second largest predeviation follicle becomes the postdeviation dominant follicle when the decreasing FSH is out of phase with the largest predeviation follicle in heifers, mares, and women or when luteolysis and predeviation are in synchrony in heifers.

Are intra follicular estradiol and oocytes quality in women undergoing assisted reproductive technology different between the right and left ovaries? An observational study

Objective

Controlled Ovarian Stimulation (COS) for In-Vitro Fertilization (IVF) or Intracytoplasmic Sperm Injection (ICSI) is considered as an assisted reproduction technology. There are established structural and biological differences between both ovaries which may affect their responsiveness to COS. Whether the right or the left ovary responds superior to COS is a question which is unresolved in the literature.

Study design

The present study was conducted as a prospective observational to make a comparison between right and left ovaries’ oocytes based on oocyte quality and follicular fluid estradiol level. A total of 100 infertile women who had referred to Infertility and Reproductive Health Research center at Shahid Beheshti University of Medical Sciences, Tehran, Iran, were investigated.

Results

The total number of very good and good oocytes were 63.01% vs. 50.3%, and immature and interstitial oocytes were 36.99% vs. 49.6% in the right and the left ovaries, respectively. There were no significant differences between oocyte rates between the two ovaries (P > 0.05).

Conclusion

Good and very good quality oocytes and fertilization rate (P < 0.001) are higher in the right ovary compared with the left ovary; however, no significant difference was observed between the right and the left ovaries in oocyte yields and cleavage rates. Moreover, despite higher follicular estradiol levels in the left ovary, there was no relationship noticed between follicular fluid estradiol and oocyte quality among oocytes of each ovary.

Unilateral oophorectomy results in compensatory follicular recruitment in the remaining ovary at time of ovarian stimulation for in vitro fertilization

OBJECTIVE

To assess the effect of unilateral oophorectomy (UO) by assessing ovarian reserve (OVR) and the response to gonadotropin stimulation in women with UO undergoing in vitro fertilization (IVF) compared with the response of the ipsilateral ovary of women without UO.

DESIGN

Historical cohort study.

SETTING

Academic fertility clinic.

PATIENT(S)

Fifty-one women with single ovary compared with a referent group with both ovaries in a 1:2 fashion.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Day-3 follicle-stimulating hormone (FSH), estradiol, and antral follicle counts as measures of OVR, and IVF outcomes including number of follicles aspirated and oocytes retrieved.

RESULT(S)

The baseline demographics and serum markers of OVR were not different. Referent women had greater follicular yield and oocyte numbers when compared with women with UO; however, when compared with the ipsilateral ovary of the referents, women with UO had a higher antral follicle count and greater follicle and oocyte numbers. In multivariate analyses, the ovary from women with UO was more likely to yield more than the median number of follicles and oocytes than the ipsilateral ovary in referent women. Live-birth rates in both groups were similar.

CONCLUSION(S)

Our results suggest that the remaining ovary appears to compensate in follicular yield after UO in women, confirming the animal data. Women with UO can be reassured and appropriately counseled regarding IVF.

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.

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.

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

BACKGROUND

The aim of this study was to evaluate whether characteristics of human ovulation correlate with age and pregnancy potential.

METHODS

Two groups of women with regular menstrual cycles were included (i.e. one fertile and one infertile group), which were divided into four age groups (< or =29, 30-34, 35-39, > or = 40 years). Monitoring included observations of follicular phase length, whether ovulations occurred from the left or right ovary, the pattern of ovulations in succeeding natural cycles and, in a subset of women, early follicular phase FSH concentrations.

RESULTS

Ovulation moving from one ovary to the other in two consecutive cycles (i.e. contralateral ovulation) was inversely correlated with age, showing a ratio of contralateral ovulation per contra plus ipsilateral ovulations (C/C+I) of 62% in women <29 years, gradually decreasing to 42% in women >40 years. The ratio of right-sided ovulation per right plus left-sided ovulations (R/R+L) was unrelated to age and remained almost constant at a level of approximately 55%. The follicular phase length was inversely correlated with age, being 16.2 +/- 2.9, 15.4 +/- 2.9, 14.8 +/- 2.8 and 13.7 +/- 1.3 days in women < 29, 30-34, 35-39 and >40 years of age respectively. The follicular phase length was similar when comparing ovulations occurring from the right and left ovary, but comparing two successive cycles, the length of the follicular phase of the second cycle, showing contralateral ovulation, was shorter than ipsilateral ovulation with two consecutive ovulations in the same ovary. The pregnancy rate of the four groups decreased with age, being 14, 12, 5 and 3% respectively. The C/C+I ratio correlates with pregnancy rate and follicular phase length, and inversely correlates with basal FSH, whereas R/R+L is unrelated to age and pregnancy rate.

CONCLUSIONS

Human ovulation shows characteristics related to age. The interaction between the two ovaries seems to be most pronounced in the younger years, where ovulations jump from one ovary to the other more frequently than later on in life. The C/C+I ratio shows a clear correlation with age and pregnancy rate.

Right-sided ovulation favours pregnancy more than left-sided ovulation

The aim of this study was to evaluate whether frequency of ovulation and fertility potential of oocytes from the two ovaries differed in regularly menstruating women (1057 cycles of 856 fertile women and 1033 cycles of 258 infertile women). For both fertile and infertile women ovulation from the right ovary occurred more often than from the left ovary (55 versus 45%; P: < 0.005). In infertile women follicular phase length was similar for right- and left-sided ovulation. However, infertile women treated with intrauterine insemination (IUI) or in-vitro fertilization (IVF) showed a pregnancy rate in connection with right-sided ovulation (13%) which was higher than that of left-sided (9%). The ratio of pregnancies deriving from the right ovary per total number of pregnancies was similar in infertile and fertile women (64.6%, 73/113 and 63.4%, 361/569 respectively). The ratio of pregnancies from right-sided ovulation (approximately 64%) per total number of pregnancies was higher than that of right-sided ovulation (approximately 55%) during non-pregnant cycles (P: < 0.0001). The implantation rate in right-sided ovulation seemed to be higher than in left-sided one, since IVF data showed a lower frequency (P: = 0.03) of pre-embryo formation from right-sided ovulation than left-sided. Mid-luteal serum oestradiol and testosterone were higher (P: < 0.05) in right-sided ovulation than left-sided. Taken together, in both fertile and infertile women the fertility potential of oocytes from the right ovary surpasses that of the left ovary.

The distribution of ovulations from the ovaries of merino and Border Leicester x merino ewes and its effect on the survival of their embryos

The distribution of ovulation between the right and the left ovary was recorded using endoscopy, in 2806 ewes over a 5-year period. Fifteen separate tests were conducted as part of the development programme for a commercial twinning vaccine. There were significantly more ovulations on the right ovary (53.4%) compared to the left ovary (46.6%; P < 0.001). The distribution of ovulation between the ovaries was not influenced by either the breed of sheep or prior immunisation against the steroid hormones androstenedione or testosterone. These findings suggest that the hormonal control of folliculogenesis and ovulation rate is modulated by unknown local factors within the ovary and its vasculature. The site of ovulation had no effect on embryo survival, and embryos from unilateral ovulations were just as likely to survive as were embryos from bilateral ovulations. However, embryo survival was influenced by ovulation rate, and ewes with ovulation rates of four or more had reduced litter sizes and lower embryo survival.

Excessive follicular recruitment and growth in mothers of spontaneous dizygotic twins

We wished to establish the frequency, regularity and laterality of multiple ovulation in mothers of dizygotic (DZ) twins and controls. Subjects had regular menses and were not using oral contraceptives. Ovarian ultrasound scans were taken over a number of cycles in 21 mothers of DZ twins and 18 controls (including 13 mothers of monozygotic [MZ] twins). Multiple large follicles (greater than or equal to 12 mm diameter) were seen significantly more frequently in mothers of DZ twins (13/21 mothers, 24/77 cycles, average +/- SE follicles/cycle 1.34 +/- 0.11) than controls (2/18 mothers, 3/31 cycles, average 1.10 +/- 0.08). Both ipsilateral and contralateral multiple follicles were observed. In one case a mother of DZ twins showed multiple large follicles in 7 out of 10 cycles in which she was scanned, including both ipsi- and contralateral patterns of occurrence.

Effect of long-term centchroman treatment on plasma steroid and peptide hormones in female rhesus monkeys (Macaca mulatta)

Effect of weekly oral administration of Centchroman (3,4-trans-2, 2-dimethyl-3-phenyl-4-(p-(beta-pyrrolidinoethoxy)-phenyl)-7-met hoxychroman) at 1 and 2.5 mg/kg for 12 months on plasma estradiol, progesterone, luteinizing hormone and follicle stimulating hormone of female rhesus monkeys was studied. Centchroman administration at both doses did not disturb the menstrual pattern of rhesus monkeys except for a prolongation of the first treatment cycle. The subsequent cycles were of normal duration. The general pattern of plasma estradiol, progesterone, luteinizing hormone and follicle stimulating hormone was not affected by Centchroman treatment. The basal and peak levels were similar in pretreatment, control and treatment cycles. The results clearly indicate that Centchroman treatment up to 1 year does not affect the hypothalamo-pituitary-ovarian axis in female rhesus monkeys.

Management of infertile patients with unilateral tubal pathology by paradoxical oophorectomy

Removal of a severely pathologic adnex to improve fertility in patients with strictly unilateral tubal disease is called paradoxical oophorectomy. This procedure was carried out in nine patients in our department. Seven of them became pregnant (78%). Four of these pregnancies occurred within a year, two during the 2nd year, and one during the 3rd year after the operation. These results were compared with the pregnancy rates in 15 patients with comparable tubal disease who were not operated on. Only four of these women became pregnant (27%); this difference is significant (P less than 0.05). Theoretic considerations and practical implications concerning paradoxical oophorectomy are discussed. We advise a wait of at least 2 years after diagnostic laparoscopy before performing paradoxical oophorectomy.

Vaginal transposition of the ovary in primates (Papio cynocephalus and Macaca arctoides)

Experimental data indicate that the time and mechanism of ovulation play a significant role in some cases of infertility and in a broad range of reproductive abnormalities. In order to establish a new experimental model for the study of these phenomena in primates, transposition of the ovary from the pelvis into the vaginal fornix was attempted in 2 species of monkeys: (a) Macaca Arctoides and (b) Papio Cynocephalus. Particularly in the latter species, ovarian relocation into the anterior and the posterior vaginal fornices proved feasible. Most ovaries continued functioning in their new location during the 2-5 months of the follow-up, despite macroscopic and microscopic evidence of infection. Post mortem examination of one of the experimental animals several years after the surgical procedure revealed the presence of an intact functioning ovary still in close contact with the vaginal fornix.

Lysis of periadnexal adhesions for correction of infertility

A series of patients is presented in whom lysis of periadnexal adhesions was carried out for correction of infertility. These 35 couples had been infertile for at least 1 year prior to surgery. Seventy-seven per cent had been trying to conceive for more than 18 months. Following diagnostic evaluation, periadnexal adhesions were found to be the sole cause of infertility in 83% of cases. Subsequent to surgery, 63% of the patients conceived, 82% within 18 months, and 57% gave birth to at least one viable child. There can be no doubt that periadnexal adhesions represent true pathology. Although often seemingly insignificant in character, at the macroscopic level, they appear to play a major role at the microscopic level in impairing ovum pickup by the fallopian tube. Gynecologists should recognize the importance of these structures as mediators of a condition of relative sterility. Thus, despite the demonstration of tubal patency, the function of the rather delicate fimbria may be compromised by periadnexal adhesions, conglutinations, and hydatids so that only a fraction of those eggs that leave the ovary at ovulation reach the interior of the fallopian tube.