The timing for IUI has to be more precise than attempting pregnancy with intercourse. There are
different methods for doing this but is there a best method? Which method is best? Stay tuned
First, some basics. When a couple has intercourse, some of the sperm get stuck
in the mucous and glands of the cervical canal. Some of those sperm never make it out but some
can be released very slowly over the course of several days. This is why it is possible for a
couple to become pregnant even if they have intercourse up to 5 days before ovulation.
An IUI is an “intrauterine” insemination. This means that the sperm are placed directly into
the uterus bypassing the cervix completely. This results in two things being different.
First, more sperm are able to reach the fallopian tubes where fertilization occurs.
Most studies show higher pregnancy rates when IUI is used compared to intercourse. Second,
because the cervix is being bypassed, the sperm doesn’t stay around for as long.
As a result, it is more important to get the sperm into the uterus
closer to the time of ovulation. Determining the timing of ovulation is therefore very important.
Ovulation occurs in human beings because of a hormone called LH or luteinizing hormone. LH
comes from the pituitary gland. Before ovulation, the amount of LH being produced by the pituitary
increases by a huge amount. This is known as the LH surge. As a result,
LH levels in the blood get higher and this can be measured with a blood test.
When the blood eventually goes through the kidneys, the LH is filtered into the urine
so LH can also be measured in the urine. This is the basis for every home urine ovulation test.
If you are planning to do an IUI and you are timing ovulation by using blood test that look at
LH levels. When should the IUI be done for maximum effect? This study looked at over 400 IUI cycles.
They compared the pregnancy rate when the IUI was performed 1 day after the LH increased to those
in which the IUI was performed 2 days after the LH increased. They found that odds for
having a positive pregnancy test were one and a half times better when the IUI happened the
day after the LH surge. The ongoing pregnancy rate was one and three quarter times better.
How about if you are using a urine ovulation test? This study looked at over 1500 IUI
cycles. Like the previous study, they looked at the pregnancy rates based on the time from when
the urine test first turned positive. They found that the pregnancy rate is best if the IUI is
performed 24 to 29 hours after the LH surge was 1st detected in the urine. 14.5% of those women
became pregnant. However, other times still produced pregnancies at nearly the same rate.
If the IUI was up to 6 hours less, between 18 and 23 hrs, the pregnancy rate was 11.3%.
If it was up to 6 hours more, between 30 and 36 hrs, the pregnancy rate was 12.8%. Based on this,
at my fertility center, IVF1, we instruct women to do their urine tests in the morning and then we
schedule IUI's for the next morning or afternoon, about 24-29 hrs after the positive urine test.
We can reassure patients that they don’t need to do their ovulation tests multiple times a day.
Excellent pregnancy rates are still possible several hours before or after that window.