Causes of Infertility
What are the common causes of infertility?
Infertility may be linked to the following causes:
- 10-15% Ovulation dysfunction
- 30-40% Pelvic factors (tubal, endometriosis, adhesions)
- 30-40% Male factor
- 15-20% Cervical factor (or abnormal sperm-mucus interaction)
- 10-15% Idiopathic or unexplained
What impact does a woman’s age have on infertility?
While a woman’s age is not usually listed as a common cause for infertility, it is increasingly a major infertility factor, as more women postpone motherhood in favor of career goals or higher education.
- A healthy fertilizable egg capable of developing into a healthy embryo is the most important factor for pregnancy.
- Because a woman is born with her lifetime supply of eggs, eggs age according to the woman’s chronological age, even if in her 30s, she manages to look 10-15 years younger.
- Nothing can be done – even theoretically – to slow down or stop egg aging, much less, reverse it.
- In some women, genetic factors cause premature ovarian failure, in which her fertilizable eggs are depleted before she turns 40.
- Egg freezing allows a woman to beat the biological clock by banking her eggs when she is younger, preferably under 30 but not older than 35.
- The female’s prime reproductive years are 18-25.
- After that, her fecundity (probability of being pregnant in a single menstrual cycle) declines considerably.
Age-related decline in fecundity (compared to women aged 18-25):
- 25-29 – by 6%
- 30-34 – by 14%
- 35-39 – by 31%
After the age of 40, a woman only has a 5% chance of pregnancy and live birth, even with IVF.
How prevalent is male infertility?
In 50-60% of infertile couples, the cause is related to the male partner, either alone or with a coinciding female factor. That is why both partners are always evaluated in fertility care.
Male infertility may be due to:
- Problems with sperm, such as:
- No sperm or only immature sperm are produced
- Low sperm count
- Poor sperm movement and abnormal sperm shapes
- Blockage or absence of the sperm ducts (vas deferens) from the testicles
- Dilated vein in the scrotum (varicocele)
- Hormonal imbalance
- Problems in delivering sperm, such as:
- Erectile or ejaculation disorders
- Previous testicular or spine injuries
- Some health factors
How do we identify male infertility?
The single basic test for the male in fertility evaluation is the semen analysis, which records:
- Semen volume (at least 1.5 cc)
- Sperm concentration (at least 20 million sperm cells per cc of semen)
- Sperm motility (at least 60% are moving with Grade 2-3 rapid progression)
- Sperm morphology (at least 14% have regular oval-shaped heads and straight tails)
- Number of immature sperm cells, if any
An abnormality in one of these parameters suggests a sperm problem.
- Since sperm parameters change constantly in the same person depending on circumstances, an abnormal semen analysis is usually repeated after four weeks to observe any change.
- If there is a severe sperm problem, the male partner will be referred to a fertility urologist for appropriate evaluation and possible treatment, especially if the patient is younger than 40.
- However, even a severe sperm problem should not and will not delay or hinder the couple from pursuing fertility treatment.
- Since only one sperm is needed to fertilize an egg, intra-cytroplasmic sperm injection (ICSI) introduces one sperm cell directly inside the egg retrieved at IVF, and the IVF embryologist only needs as many sperm cells as the number of mature eggs retrieved from the wife. (Before ICSI was perfected in the 1990s, IVF could not be performed if the male had less than 10 million sperm per cc. Today, it is done even if the semen sample only contains rare moving sperm.)
How common is unexplained infertility?
Approximately 10-25% of all couples undergoing infertility treatment are diagnosed with “unexplained infertility.”
- This means that the causes of their infertility are subtle and cannot be explained using the tests available to fertility specialists.
- The prognosis for couples with unexplained infertility depends primarily upon the age of the couple.
- The success rate is 15-20% for unexplained infertility treated with fertility medications and intrauterine inseminations (IUI), which is similar to the 20% monthly fecundity of a normally fertile woman.
- The success rate with IVF treatment, when the woman is 35 or younger, may be 50-60%, which is the prevailing pregnancy rate in most IVF programs.
- IVF often identifies the underlying problem to be related to egg quality and embryo implantation (a uterine problem).
What are the chances of conception if there are no obvious fertility problems?
- Woman is younger than 30
- Previous full-term pregnancy
- Trying less than 3 years
- Not underweight, overweight or obese
- Both partners don’t smoke
- Less than 2 cups of coffee daily
- No use of recreational drugs
- Woman is older than 35
- Never conceived before
- Trying more than 3 years
- More than 2 spontaneous abortions or stillbirths
- Underweight, overweight or obese
- One or both partners smoke
- More than 2 cups of coffee daily
- Regular or recent use of recreational drugs