Ovulation Induction – How Can it Help You?

Ovulation disorders account for up to 40% of female fertility issues.

This is due to:

-          PCOS

-          Hypothalamic amenorrhea

-          Thyroid disease

-          Adrenal disease

-          Endometriosis

-          High prolactin

-          Age

-          Reduction in ovarian reserve

-          Premature ovarian failure

Ovulation Induction:            

Medication to induce ovulation is usually Clomid or Letrozole. Both of these medications are oral tablets that help the ovaries develop and ovulate eggs.

Clomid:

Clomid is an anti-oestrogen medication. It binds to oestrogen receptors in the brain, blocking oestrogen in the hypothalamus and tricking the brain into thinking that oestrogen levels are low.  It is taken consecutively between days 2-6 or days 5-9 of the menstrual cycle. When you stop taking the medication, the temporary block is removed and the hypothalamus (in the brain) releases more gonadotrophin releasing hormone (GnRH) which stimulates the pituitary gland to produce more FSH and LH which are needed for follicle development and ovulation.

Side Effects: 

In Chinese Medicine it causes Yin deficiency which can lead to a thin uterine lining and reduced cervical mucus, which are both needed for optimal fertilisation and implantation.

It can also cause ovarian cysts, nausea, abdominal cramps, hot flushes and mood swings.

Although 92% of clomid pregnancies are classified as singleton pregnancies, 7% are twins, with 0.5% being triplets. Clomid increases the likelihood of a twin pregnancy.

Useful for:  

·       Women with ovulation disorders

·       Women with endometriosis

·       Mild male factor

·       Often used for unexplained fertility issues

·       Women with a normal BMI 

Women with a BMI over 25 and with insulin resistance and/or high androgens are often Clomid resistant.

Letrozole:  

Letrozole works on the level of the ovary by blocking the enzyme aromatase which converts androgens into oestrogen. Androgens are the male sex hormone that are often in excess with PCOS. Therefore letrozole is preferred for women with high androgens. We can see this through your hormone blood test results for testosterone and sex hormone binding globulin.

By reducing oestrogen, letrozole causes the pituitary gland to release FSH and LH. Letrozole is often preferred to or used as an alternative to clomid, especially if patients have not responded to clomid treatment in the past. It is also taken for 5 days from day 2 of the menstrual cycle.

Side Effects: 

In Chinese Medicine it causes Yin deficiency. Side effects can include hot flushes, dizziness and headaches. It can increase the risk of multiple pregnancies. In the long term, it may contribute to osteoporosis. On the plus side, letrozole doesn’t thin the uterine lining, as can happen with clomid as it is removed from the body much quicker than clomid.

Useful for:

·       Women with PCOS

·       Mild male factor

·       Women with a high BMI 

Clomid v Letrozole Effectiveness?

A study comparing letrozole and clomid was published in 2020 with PCOS women who didn’t previously ovulate. It showed that the ovulation rates for letrozole were 86.7% and the ovulation rates for clomid were 85.2%.

Research suggests that although ovulation rates are high, ovulation induction treatment does not affect implantation and therefore pregnancy rates are lower at 50%.

In a 2014 study, researchers found that 27.5% of women treated with letrozole had a live birth. Only 19.1% of women treated with clomid had a live birth.

Researchers over both studies concluded that letrozole is a better alternative for ovulation induction for women with PCOS as it produced higher pregnancy rates and shorter times to achieve pregnancy.

How Should Ovulation Induction be Monitored?

Clomid or letrozole should not be used for more than 3 consecutive cycles and not more than 6 months in total. They should also be used with regular tracking scans through the cycle.

1.      Take clomid or letrozole for the days prescribed.

2.      Blood tests to carefully monitor hormone levels.

3.      Follicle tracking scans throughout the cycle.

This is to avoid multiple pregnancy, missed ovulation or progesterone levels being too low in the luteal phase.

Ovulation Induction and IUI

In IUI cycles, ovulation induction medication is often used in conjunction with follicle tracking and sometimes a HCG trigger injection to ensure ovulation. Although injected stimulation medication can be used as part of the IUI cycle, letrozole is often a milder alternative.

Which is Best for Me?

Letrozole usually is seen as the favourable medication. This is because:

·       It maintains the uterine lining

·       It has a higher rate of mono-follicular cycles and therefore single pregnancies

·       Research suggests a greater instance of live births

·       It is more suitable for women with a high BMI, insulin resistance, PCOS or high testosterone.

·       It can be tried if clomid has not worked before.

Clomid may be better for you if you have a normal BMI.

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