It is a known fact that many women of the new millennium are settling down to having babies much later than before now. Nigerian women are no excepyion.
This imposes on them the double risks of declining fertility and complications arising from age- related reproductive ill- health i.e. miscarriages, fibroids e.t.c.
In this update our team of experts examines the influence of maternal age on fertility.
Advancing maternal age is an independent risk factor of infertility. This has been shown conclusively by studies carried out on religious groups who do not use birth control and who have high birth rates.
After age 30, fertility rates declines substantially and by age 35 a woman has half the chance of becoming pregnant than she did at 25.
In addition, it is now known that women of older reproductive age have a large number of unrecognized pregnancy losses.
In contrast, it is worth noting that the age of the male partner does not affect the ability of the sperm cells he produces to fertilize an oocyte when they come in contact.
The effect of the female’s age on her fertility is dramatic and as stated earlier, quite progressive.
This process is also reflected in the live birth rate and has been remarkably stable over time and geography.
Miscarriages are also more frequent as a woman’s age rises. Although one may suggest that this is because of the well-known increase in chromosomal abnormalities with increasing mother’s age, normal pregnancies are also lost with higher frequency as the mother’s age increases.
The effect of a woman’s age on fertility is theoretically an effect of a larger proportion of abnormal embryos with increasing woman’s age.
Facts obtained from in-vitro fertilization in which normal appearing embryos were examined with special instruments (fluorescent in situ hybridization (FISH), revealed 39% abnormal embryos from women who are greater or equal to 40 years of age compared to 5% from women who are 20 to 34 years of age.
The direct effect of a woman’s age is apparently on the ovarian reserve and ovarian responsiveness to FSH (Follicle Stimulating Hormone) in the recruitment and growth of follicles. This in simple term means how quickly and readily the ovaries can perform its function of producing egg and hormone depends on a woman’s age.
Many reproductive endocrinologist feel that the following groups of infertile women should undergo an assessment of this readiness since they are more likely to have problems producing eggs.
There are two commonly used tests of ovarian readiness to work properly i.e. to produce eggs and its own hormones.
Both rely on measuring blood levels of a hormone called FSH (Follicle Stimulation Hormone)
If the FSH level is higher than normal, then the probability of achieving pregnancy is reduced.
The predictive significance of these tests depends on the type of method used. Therefore it is important to make sure that the laboratory meets the published criteria for the hormones tests (Coefficient of variation).
The day -3 FSH test
The day-3 FSH test consists of measuring the blood level of FSH on the third day of the menstrual cycle. In practice, the test is equally valid if performed on days 2,3, or 4.
Numerous studies have shown that at most, only 5% of women with a higher than normal FSH level succeed in conceiving even with in-vitro fertilization.
Upper limits used range from 11 to 14 IU/L.
An abnormal test result is associated with a poor pregnancy rate irrespective of age.
On the other hand, note that a normal result does not necessarily mean that a patient will achieve pregnancy with in vitro fertilization.
The live birth rates per 100 IVF cycles monitored;
B. The Clomiphene challenge test
The clomiphene challenge test is a more sensitive test of ovarian readiness: in studies, twice as many patients were identified as poor responders to stimulation with this test than with a day-3 FSH hormone level alone.
In the clomiphene challenge test the patient has her FSH hormone level measured on the third day of her menstrual cycle, and then takes clomiphene citrate (Clomid, ikacolmin; an antiestrogen) 100mg daily on days through to day 9 then has her FSH hormone level measured again on day 10.
Results are considered abnormal if any level is higher than 10 to 12 IU/L.
Alternatively, the day3 and day 10 blood FSH hormone levels can be added together. In a certain study, no woman became pregnant who had a summed FSH i.i. (day 3 + day 10 FSH) level greater than 26.
The usefulness of the clomiphene challenge test has proven in a general in fertility population as well as in patients undergoing ovarian stimulation with gonadotropins.
The incidence of abnormal test results increases with age:
Although an abnormal result on the clomiphene challenge test has a predictive value of 95% to 100% for not achieving pregnancy, the test still has poor sensitivity for identifying patients for whom infertility treatment will not succeed.
This is another hormone test useful in predicting the readiness of the ovary to perform its function.
A day-3 estradiol level greater than 80pg/ml is also associated with a poor response to medical treatment of infertility.
Inhibin is made in the ovary. It inhibits the production of FSH hormone. The abnormally high serum levels of FSh seen in infertile women have been attributed to decreased production of inhibin. Although measuring blood inhibin levels may prove to be a better assess ment of ovarian readiness, the test is not available in many centers.