Is GnRH self-priming an obligatory feature of the reproductive cycle?

Insufficient suppression of LH (premature elevation) and FSH (prolonged release) give rise to blood concentrations which may cause damaging effects on oocyte viability and too many follicles respectively. During the surge, LH rises from low to high threshold values to initiate processes from initiation of the resumption of oocyte meiosis to the induction of ovulation. In general, it is thought that a dramatic increase in LH concentration is required to attain the high threshold for ovulation. A self-priming mechanism, by which gonadotrophin-releasing hormone (GnRH) enhances the LH (and FSH) responses to its own action, was thought to be responsible. However, normal LH surges in rats consist of <2-7% of the maximal pituitary releasing capacity. The physiological roles of LH and FSH favour a control mechanism that restrains their blood concentrations during most of the cycle. Ovarian proteins, e.g. inhibin and putative gonadotrophin-surge-inhibiting factor/attenuating factor (GnSIF/AF), are involved in this process. We argue that the increased pituitary LH responsiveness during the mid-cycle surge is not the result of a self-priming process that 'dramatically' increases the LH releasing capacity of the pituitary gland. This is probably due to elimination by GnRH of the inhibitory action of the putative ovarian proteins GnSIF/AF.

Effect of an oral contraceptive containing drospirenone on the renin-angiotensin-aldosterone system in healthy female volunteers

Drospirenone is a new synthetic progestogen with both progestational, antimineralocorticoid and antiandrogenic properties. In combination with ethinylestradiol, it is being developed as an oral contraceptive which will contain 30 micrograms ethinylestradiol and 3 mg drospirenone (Yasmin, Schering AG, Germany). The effects of drospirenone alone, and in combination with ethinylestradiol, upon the renin-angiotensin-aldosterone system (RAAS) have been evaluated in healthy female volunteers. RAAS activity was assessed by measurement of plasma renin substrate (PRS) concentration (otherwise known as angiotensinogen), plasma renin activity (PRA), and plasma aldosterone (P-Aldo) concentration. An antimineralocorticoid effect was observed when volunteers received drospirenone alone at doses in the range 0.5-3.0 mg/day for one cycle. The effect was dose-dependent for P-Aldo but was not dose-dependent for PRA. When ethinylestradiol (30 micrograms) was combined with either 2 mg or 3 mg drospirenone and given to volunteers for three cycles, an increase in PRS was observed with both preparations, which was indicative of estrogenic stimulation, and increases in PRA and P-Aldo were shown which were indicative of an antimineralocorticoid effect of drospirenone. Increases in PRA and P-Aldo were significantly higher with the preparation containing 3 mg drospirenone in cycle 1 but not in cycle 3. The effect of the preparation containing 30 micrograms ethinylestradiol/3 mg drospirenone upon RAS activity was also compared with that of a commercially available preparation also containing 30 micrograms ethinylestradiol but combined with 150 micrograms desogestrel (Marvelon). Over a period of 13 cycles, increases in PRS were seen with both treatments, the effect being slightly more pronounced with 30 micrograms ethinylestradiol/150 micrograms desogestrel. A markedly greater increase in PRA was seen following treatment with 30 micrograms ethinylestradiol/3 mg drospirenone, and, in cycle 3, this difference was statistically significant. In contrast, P-Aldo was increased markedly with 30 micrograms ethinylestradiol/3 mg drospirenone in all measured cycles, whereas, in the 30 micrograms ethinylestradiol/150 micrograms desogestrel group, changes were minimal. The increases in PRA and P-Aldo are interpreted as endogenous counter-regulation against the antimineralocorticoid activity of drospirenone. PRS increases under all combinations are an expression of estrogenic stimulation. Measurement of body weight and blood pressure in the studies with combined ethinylestradiol and drospirenone revealed that drospirenone was associated with either stable body weight or with a slight loss in body weight, while blood pressure remained largely unchanged. Overall, the results indicate that 30 micrograms ethinylestradiol/3 mg drospirenone has a distinct antimineralocorticoid effect.

Obstetric outcome of twin pregnancies after in-vitro fertilization: a matched control study in four Dutch university hospitals

In singleton pregnancies after in-vitro fertilization (IVF), increased rates of obstetric and perinatal complications have been reported. Studies that compared IVF twin pregnancies with spontaneously conceived twins have yielded conflicting results. We compared 96 IVF twin pregnancies to 96 controls after elaborate matching. The design of our study precluded matching by zygosity. The monozygosity rate was higher in the control group and this implies that beforehand the risk for a less favourable outcome in the control group was higher than in the IVF group. However, the average birthweight of the IVF children was less than that of children in the control group (P = 0.04). This was not due to more intrauterine growth retardation in the IVF group. The mean gestational age at birth was 5 days shorter in IVF than control pregnancies, and although this difference was not significant it might explain the lower birthweight in the IVF group. The discordance rate in the IVF group was significantly increased. We found no difference in perinatal mortality and morbidity. We conclude that this study provides further evidence for a different outcome of IVF twin pregnancies in comparison with spontaneously conceived twin pregnancies.

Inhibition of ovulation by a novel progestogen (drospirenone) alone or in combination with ethinylestradiol

OBJECTIVE

To investigate ovulation inhibition with drospirenone, a novel progestogen that has a profile similar to natural progesterone, when given alone or in combination with ethinylestradiol.

METHOD

Hormonal parameters (LH, FSH, 17beta-estradiol and progesterone) and peripheral parameters (cervical score, spinnbarkeit and crystallization), as well as follicle size assessed by ultrasonography, were measured in two groups of healthy women. Forty-eight women aged 19-35 years were randomly assigned to receive 0.5 mg, 1.0 mg, 2.0 mg or 3.0 mg of drospirenone over a single treatment cycle, and 52 women aged 20-35 years were randomized to receive either 2 mg drospirenone/30 microg ethinylestradiol or 3 mg drospirenone/30 microg ethinylestradiol over three treatment cycles. Baseline measurements were taken during a control pretreatment cycle.

RESULTS

Adequate ovarian suppression with drospirenone alone was evident at dose levels of 2 and 3 mg, and at 3 mg all subjects had anovulatory cycles. Although both combined preparations (2 mg and 3 mg drospirenone/30 microg ethinylestradiol) inhibited the hypothalamic-pituitary-ovarian axis, follicular maturation leading to escape ovulation was observed in three subjects in the 2 mg drospirenone/30 microg ethinylestradiol group. Only one of these ovulations was considered to be definitely the result of treatment failure. All cycles in the 3 mg drospirenone/30 microg ethinylestradiol group were anovulatory. No statistically significant difference was found between treatment groups.

CONCLUSION

The combination of 3 mg drospirenone/30 microg ethinylestradiol (Yasmin, Schering AG) reliably inhibits ovulation, with a low frequency of follicular maturation, and provides a reasonable safety margin.

[Handling small relative risks in science and management: the third-generation pill]

Small relative risks (a twofold or lesser increase in disease frequency) become scientifically acceptable with (a) repeated consistent findings from studies that (b) address the most important forms of bias and confounding, and (c) when there is a plausible biologic mechanism. The third-generation oral contraceptive controversy is an example of such a relevant but small relative risk and demonstrates the problem of interpretation and implementation into medical practice guidelines.

Higher risk of venous thrombosis during early use of oral contraceptives in women with inherited clotting defects

BACKGROUND

Results of recent studies show that the risk for venous thrombosis is highest during initial oral contraceptive use. This suggests a subgroup of females who are at immediate risk of thrombosis when exposed to oral contraceptives.

OBJECTIVE

To determine whether women with inherited clotting defects who use oral contraceptives develop venous thrombosis at an earlier stage than do those without inherited clotting defects.

METHODS

Analysis of the data from the Leiden Thrombophilia Study, a population-based case-control study with data on duration of oral contraceptive use and recently detected genetic coagulation disorders. Patients had a first episode of objectively proven deep vein thrombosis. Patients and controls were considered thrombophilic when they had protein C deficiency, protein S deficiency, antithrombin deficiency, factor V Leiden mutation, or prothrombin 20210 A mutation.

RESULTS

Risk of developing deep vein thrombosis was greatest in the first 6 months and the first year of oral contraceptive use. Compared with prolonged use, the risk of developing deep vein thrombosis was 3-fold higher in the first 6 months of use (95% confidence interval [CI], 0.6-14.8) and 2-fold higher in the first year of use (95% CI, 0.6-6.1). Patients who developed venous thrombosis in the early periods of use were more often thrombophilic. Among women with thrombophilia, the risk of developing deep vein thrombosis during the first 6 months of oral contraceptive use (compared with prolonged use) was increased 19-fold (95% CI, 1.9-175.7), and in the first year of use, it was increased 11-fold (95% CI, 2.1-57.3).

CONCLUSIONS

Women with inherited clotting defects who use oral contraceptives develop venous thrombosis not only more often but also sooner than do those without inherited clotting defects. Venous thrombosis in the first period of oral contraceptive use might indicate the presence of an inherited clotting defect.

Intracytoplasmic sperm injection: position of the polar body affects pregnancy rate

A prospective study on intracytoplasmic sperm injection (ICSI) was performed to evaluate the effect of the position of the polar body relative to the opening of the injection needle during sperm injection, and of the person who performs the injections on fertilization, cleavage, and pregnancy rates. This study included 173 couples undergoing 313 ICSI cycles from September 1995 to December 1997. All injections were performed by two persons. For each injected oocyte the person who performed the injection was recorded as well as the position of the polar body during injection (6 o'clock: animal pole towards the opening of the needle; 12 o'clock: animal pole away from the opening of the needle). Of 2630 oocytes retrieved, 2232 were injected. Significantly more oocytes developed two pronuclei after injection with the polar body at 6 o'clock versus 12 o'clock (P = 0.01; 51 versus 45% respectively) and after injection by person 1 versus person 2 (P = 0.02; 50 and 45% respectively). Higher pregnancy rate (P = 0.046) was found after transfer of embryos from oocytes injected with the polar body at 6 o'clock (36%) versus 12 o'clock (18%). This was the result of a significant interaction (P = 0.03) between the position of the polar body and the person performing the injections. Given the higher fertilization rate in the 6 o'clock group, it is recommended that oocytes be injected with the polar body at 6 o'clock. The higher pregnancy rate as a result of polar body position and the interaction between polar body position and the operator suggest variations in injection technique.

Preeclampsia and genetic risk factors for thrombosis: a case-control study

OBJECTIVE

Recently, it has been proposed that hereditary coagulation abnormalities leading to an increased venous thrombosis risk may play a role in the development of preeclampsia. We tested this hypothesis in women who have had preeclampsia compared with matched control subjects.

STUDY DESIGN

We conducted a case-control study of 163 women with preeclampsia during 1991-1996. Control subjects were matched for age and delivery date. Patients and control subjects were tested for the presence of factor V Leiden, prothrombin 20210A allele, protein C, protein S, and antithrombin deficiency. Logistic regression methods were used for data analysis.

RESULTS

The prevalence of these genetic risk factors was similar in the patient group (12.9%) and the control group (12.9%; odds ratio, 1.0; 95% confidence interval, 0.5-3.9). Unexpectedly, we found a high prevalence of factor V Leiden in the control group (9.2%).

CONCLUSION

We found no differences in the prevalence of genetic risk factors of thrombosis in women with preeclampsia compared with control subjects.

Venous thrombosis, oral contraceptives and high factor VIII levels

Recently, it has been described that elevated plasma levels of factor VIII are a strong risk factor for venous thrombosis. We analysed the data of the Leiden Thrombophilia Study, a population based case-control study on the causes of venous thrombosis, to verify whether the risk due to oral contraceptive use was higher in women with higher factor VIII levels. Furthermore we investigated the joint risk of high factor VIII levels and oral contraceptive use. We selected 155 premenopausal women with deep-vein thrombosis and 169 control subjects, aged 15-49, who were at the time of their thrombosis (or similar date in control) not pregnant, nor in the puerperium, did not have a recent miscarriage, and were not using injectable progestogens. Of the patients, 109 (70%) women had used oral contraceptives during the month preceding their deep-vein thrombosis, in contrast to 65 (38%) of the control subjects (index date), yielding an odds ratio for oral contraceptive use of 3.8 (95% CI 2.4-6.0). Of the women who suffered a deep-vein thrombosis 56 (36%) had high factor VIII levels (> or =150 IU/dl) as compared with 29 (17%) of the control subjects, yielding an odds ratio for high factor VIII of 4.0 (95% CI 2.0-8.0), relative to factor VIII levels <100 IU/dl. The joint effect of oral contraceptive use and high factor VIII resulted in an odds ratio of 10.3 (95% CI 3.7-28.9), comparing women who had both with women who had neither. We conclude that there is an increase in risk due to oral contraceptive use in women with higher factor VIII levels and that both factors have additive effects.

Risk of venous thrombosis with use of current low-dose oral contraceptives is not explained by diagnostic suspicion and referral bias

BACKGROUND

The magnitude of the relative risk of venous thrombosis caused by low-dose oral contraceptive use is still debated because previous studies might have been affected by diagnostic suspicion and referral bias.

METHODS

We conducted a case-control study in which the effect of diagnostic suspicion and referral bias was excluded. The study was performed in 2 diagnostic centers to which patients with clinically suspected deep vein thrombosis of the leg were referred. History of oral contraceptive use was obtained before objective testing for thrombosis. Young females with an objective diagnosis of deep vein thrombosis were considered case patients, and those who were referred with the same clinical suspicion but who had no thrombosis served as control subjects. Participants were seen between September 1, 1982, and October 18, 1995: 185 consecutive patients and 591 controls aged 15 to 49 years with a first episode of venous thrombosis and without malignant neoplasms, pregnancy, or known inherited clotting defects.

RESULTS

The overall odds ratio for oral contraceptive use was 3.2 (95% confidence interval [CI], 2.3-4.5); after adjustment for age, family history of venous thrombosis, calendar time, and center, the odds ratio was 3.9 (95% CI, 2.6-5.7). In the idiopathic group (120 patients and 413 controls, excluding recent surgery, trauma, or immobilization), the odds ratio for oral contraceptive use was 3.8 (95% CI, 2.5-5.9); after adjustment, the odds ratio was 5.0 (95% CI, 3.1-8.2).

CONCLUSIONS

In this study, in which patients and controls were subj ect to the same referral and diagnostic procedures, we found similar relative risk estimates for oral contraceptive use as in previous studies. We conclude that diagnostic suspicion and referral bias did not play an important role in previous studies and that the risk of venous thrombosis with use of current brands of oral contraceptives still exists.

Hemostatic effects of oral contraceptives in women who developed deep-vein thrombosis while using oral contraceptives

OBJECTIVE

Comparison of the effect of oral contraceptives on hemostatic variables in venous thrombosis patients (thrombosis while using oral contraceptives) with the effect in healthy control subjects. Our aim was to assess whether some of these effects were more pronounced in women who had suffered thrombosis, i.e., whether these were "hemostatic hyperresponders".

STUDY DESIGN

A population-based case-control study, the Leiden Thrombophilia Study.

MATERIALS AND METHODS

We investigated 99 pre-menopausal women, age 15-49 years, who had used oral contraceptives at the time of a first, objectively confirmed episode of deep-vein thrombosis. They were not pregnant, nor in puerperium, nor had had a recent miscarriage, and were not using injectable progestogens, nor suffering from inherited coagulation defects. The median time between occurrence of deep-vein thrombosis and venepuncture was 18 months, and 30 of the 99 women were still using oral contraceptives, while 69 had discontinued oral contraceptive use. In addition, a group of 153 control women (54 of them were oral contraceptive users and 99 were non-users) were studied. The following hemostatic variables were measured: APTT, factor VII, factor VIII, factor XII, fibrinogen, prothrombin, total antithrombin, normalised activated protein C sensitivity ratio (n-APC-sr), protein C, protein S and free protein S.

RESULTS

We found marked and significant effects of oral contraceptive use on the levels of several clotting factors, with an increase in factor VII, factor XII, protein C and a decrease in antithrombin, n-APC-sr and protein S. Less marked effects that were non-significant or only significant in either patients or controls, were an increase in factor VIII, fibrinogen and prothrombin and a decrease in the APTT and free protein S. In the former thrombosis patients several of these effects of oral contraceptives were more pronounced than in healthy women: specifically on factor VII, antithrombin, n-APC-sr and protein C.

CONCLUSIONS

Our results of the effects of oral contraceptives generally confirm previous reports in healthy volunteers. Our data also show that in former deep-vein thrombosis patients these effects are more pronounced. Apparently some women become "high hemostatic responders" when exposed to oral contraceptives, and they may be the women most vulnerable to its thrombogenic effects.

Effectiveness of the postcoital test: randomised controlled trial

OBJECTIVES

To investigate the impact of the postcoital test on the pregnancy rate among subfertile couples and on the number of other diagnostic tests and treatments.

DESIGN

Randomised controlled study.

SETTING

A university and two non-university teaching hospitals in the Netherlands.

SUBJECTS

New couples at infertility clinics, 1 March 1993 to 1 October 1995; randomisation to an intervention group (series of infertility investigations that include the postcoital test) or to a control group (series excluding the test).

MAIN OUTCOME MEASURE

Cumulative pregnancy rate.

RESULTS

Of 736 consecutive new couples, 444 fulfilled the inclusion criteria and consented to participate (intervention group, 227; control group, 217). Treatment was given more often in the intervention group than in the control group (54% v 41%; difference 13% (95% confidence interval 4% to 22%)). Yet cumulative pregnancy rates at 24 months in the intervention group (49% (42% to 55%)) and the control group (48% (42% to 55%)) were closely similar (difference 1% (-9.0% to 9.0%)).

CONCLUSION

Routine use of the postcoital test in infertility investigations leads to more tests and treatments but has no significant effect on the pregnancy rate.

Evaluation of pregnancy rates after intrauterine insemination according to indication, age, and sperm parameters

PURPOSE

Our purpose was to evaluate intrauterine insemination results obtained in our clinic and identify prognostic factors for the chance of pregnancy.

METHODS

A retrospective study of data from 1989 to 1996 was undertaken. Only first attempts were included in this study, except for the part on the cumulative pregnancy rates. Couples with either one-sided tubapathology, hormonal dysfunction, idiopathic infertility, or andrological indication were selected. All women were stimulated with clomiphene citrate. Five hundred sixty-six couples who underwent 1763 cycles were included in the study.

RESULTS

The overall pregnancy rate for first pregnancies was 6.9% per cycle and 21.4% per patient. For first intrauterine insemination attempts this was 8.8% per cycle/patient, varying between 5.0% for andrological indication and 10.6% for tubapathology, 10.0% for idiopatic indication, and 10.3% for hormonal indication. These differences were not significant. Age did not have a significant effect either, although there were no pregnancies observed in women 40 years or older. The number of inseminated spermatozoa significantly affected the pregnancy rate: < 2 million, 4.6%; > or = 2 to < 10 million, 3.9%; and > or = 10 million, 11.3%.

CONCLUSIONS

Unless semen characteristics are insufficient, intrauterine insemination is a useful treatment for infertile couples.

Which prostanoid metabolites should be determined for the study of reproductive processes?

The non-enzymatic metabolites of prostacyclin (PGI2) and thromboxane A2 (TXA2), 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha) and thromboxane B2 (TXB2), and their 2,3-dinor metabolites, 2,3-dinor-6-keto-PGF1alpha and 2,3-dinor-TXB2, were measured in early morning urine samples in 24 in vitro fertilization (IVF) cycles in 24 women and in 27 women who became pregnant after IVF and embryo transfer (ET). The sum of the non-enzymatic metabolites and their 2,3-dinor metabolites was considered to be a reflection of total PGI2 and total TXA2 production in vivo. Both the ratio of 'total' PGI2/'total' TXA2 and the ratio of the 2,3-dinor metabolites were calculated. TXB2 concentrations showed virtually no change and the ratios of the non-enzymatic metabolites of PGI2 and TXA2 versus their 2,3-dinor metabolites remained relatively constant. As a consequence, the ratio of 2,3-dinor-6-keto-PGF1alpha/2,3-dinor-TXB2 was a close reflection of the ratio of 'total' PGI2/'total' TXA2, although the latter ratio was significantly higher all the time. We conclude that for comparative studies on the balance between PGI2 and TXA2 in IVF cycles and during gestation, the determination of the 2,3-dinor metabolites alone can replace the measurement of all four metabolites.

Third-generation oral contraceptive and deep venous thrombosis: from epidemiologic controversy to new insight in coagulation

Four epidemiologic studies showed a twofold increase in risk of deep venous thrombosis with the use of oral contraceptives containing third-generation progestins, relative to second-generation products. These findings have been strongly debated ever since, and new studies have been added. In the current article we examine whether the findings can be explained by potential biases or other shortcomings of the epidemiologic studies. We conclude that complete certainty cannot exist but that the most rational conclusion from the epidemiologic findings and their discussion is that an increased risk of deep venous thrombosis with third-generation contraceptives is likely, especially in first-time and young users. The controversy has recently led to new insights in coagulation: Women who use third-generation contraceptives acquire a resistance to the blood's own anticoagulation system, similar to the activated protein C resistance that is seen in persons who carry the factor V Leiden mutation but different from that in women using second-generation contraceptives.