Predicting conception

The postcoital test in the development of new vaginal contraceptives†

Postcoital tests (PCTs) have been used for over a century in the clinical evaluation of infertile couples, and for nearly 70 years in the evaluation of new vaginal contraceptive products. PCTs have been largely replaced by more modern methods in the study of infertility, but they remain the most useful way to obtain preliminary data on the effectiveness of vaginal contraceptive products. The World Health Organization has described important aspects of the procedure. It involves collection of cervical mucus at a certain time point after intercourse and the counting and characterization of sperm found in the mucus. A wide range of progressively motile sperm (PMS) has been associated with pregnancy rates in infertility studies. Eligibility for contraceptive trials includes the requirement that couples achieve a certain threshold number of PMS per high power field at midcycle in a baseline cycle without the test product. The primary endpoint, or definition of a satisfactory result in test cycles, is predefined. A literature review identified 10 PCT studies of vaginal contraceptives involving nine test products. Phase II trials of vaginal contraceptives have not been deemed feasible in the development of any vaginal contraceptive to date. A PCT study of a test product can be predictive of contraceptive efficacy, although ultimate contraceptive effectiveness is influenced by the ease of use of the product, along with patient compliance. PCT results similar to results seen with products that later showed satisfactory performance in efficacy trials is the best indicator of likely success of a test product.

Likelihood of natural conception following treatment by IVF

PURPOSE

To predict the ongoing likelihood of natural conception, when a couple has ceased to try to conceive by assisted conception.

METHODS

A postal questionnaire survey obtained information on further attempts to conceive and have a baby, either without treatment or by treatment elsewhere.

RESULTS

From a response rate of 44%, there were 116 couples who fulfilled the study criteria. The data presented are based on this group. The overall likelihood of conception was 18%. Cumulative results were analysed up to 3 years following treatment. Univariate analysis showed that likelihood of conception was affected by infertility diagnosis (p = 0.024), woman's age (> 38 years; p < 0.005) (negatively) and duration of infertility (< 3 years; p < 0.005) (positively), while primary infertility did not. Effects of diagnosis and infertility duration were confirmed by multivariable analysis, controlling for age and primary infertility. These latter variables had no independent effect.

CONCLUSION

The likelihood of natural conception following IVF treatment was determined by duration of infertility and diagnosis; tubal disease in particular was associated with a very poor likelihood of natural conception.

Male infertility: tales of progress and frustration

This article describes andrology research, inspired by Professor Michael Hull, to develop sperm function tests and to understand the basic causes of male infertility. No generally acceptable sperm function test has yet been devised. Computer-assisted semen analysis (CASA) proved of limited value in predicting the outcome of in vitro fertilization (IVF) although it was more useful in donor insemination. High intracellular Ca2+ activity, [Ca2+]i, is involved in decreasing motility in cryopreserved sperm. Capacitative calcium entry after depletion of intracellular stores may generate the sustained increase in [Ca2+]i that initiates the acrosome reaction. Our data support the presence of Ca2+ stores as thapsigargin increased [Ca2+]i in sperm in Ca2+ -free medium. Recent observations indicate that cAMP enhances capacitative calcium entry, acting upstream of emptying of the store. Excess reactive oxygen species (ROS) is an important cause of sperm pathology but at low concentrations ROS regulate capacitation. Our evidence shows that ROS are produced by leucocytes present in sperm suspensions. We have been unable to demonstrate that human sperm produce ROS. The relationship between ROS production and lipid peroxidation indicates that sperm from some men are resistant to lipid peroxidation, possibly because of better antioxidant defences. We conclude that the future of andrology lies in the identification of the basic causes of infertility and not in more detailed descriptions of the properties of semen.