If you study a large number of people who ovulate, you will find that some of them ovulate early,
some of them ovulate later and most ovulate somewhere in the middle. What is considered a
normal ovulation time? What are the reasons why some people take longer to ovulate? Stay tuned.
First, what is considered a normal time for ovulation? I was taught that normal
meant the length of time from one period to the next was 28 days and that ovulation
normally occurs on day 14. How accurate is that in the real world? Last year,
scientists from Australia did a study of 1.5 million women who were tracking their ovulation
and cycle information on a phone app. Only 16% of them had a cycle length of 28 days. Just under
20,000 people tracked their day of ovulation. Here is the data from that analysis.
As you can see, there was a wide range in the days that people ovulated. More people
ovulated on day 14 of their cycle compared to any other single day but nearly as many
ovulated on day 13 and 15. Over one third ovula ted over those three days. 80% ovulated between
day 12 and day 20. Statistically we can call this the normal range for
ovulation. If you are not ovulating until Day 21, we can call that late ovulation.
What are the causes for late ovulation? It
tends to be the same factors that cause people not to ovulate at all.
The most common cause for ovulation problems is polycystic ovary syndrome or PCOS. This
affects six to 12 percent of people of reproductive age in the United States.
PCOS can be challenging to diagnose because there are so many differences in people who
have PCOS. Some people with PCOS are overweight but some are thin. Some have symptoms like
unwanted hair growth or hair loss and some do not. To make things even more complicated,
different medical organizations have different criteria for making a diagnosis of PCOS.
Another cause for late ovulation is hypothyroidism. This is when the thyroid
gland does not produce normal levels of the thyroid hormones. About one in every five
adults may have hypothyroidism but not all of them will have ovulation problems. Unlike PCOS,
hypothyroidism is easy to diagnose with a blood test and easy to treat with medication.
Some people may have high levels of a hormone made in the pituitary gland called prolactin.
This is known as hyperprolactinemia. When levels of prolactin are very high, ovulation may not
occur at all. In less severe cases, it may cause delayed ovulation. There are several forms of
prolactin in the body but only one form interferes with ovulation. Make sure you watch this video
to learn how to test for prolactin correctly so that you don’t get treated unnecessarily.
Although most people aren't aware of it, exercising too much can also delay ovulation.
Ovulation requires energy from your body. People who exercise vigorously burn a lot of calories.
If they don’t eat enough calories to keep up this will interfere with ovulation. It is more
common to see this problem in runners and dancers who are thin but it can happen to anybody who
burns more calories than they consume. The treatment is to exercise less or eat more or both.
What about vitamins? A study from researchers at Harvard University found that women who reported
lower iron intake were more likely to have ovulation problems. In 2006,
a study was conducted on nearly 20,000 women who were trying to become pregnant. The results
showed that women who took iron supplements were 40% less likely to report ovulation problems.
The Time to Conceive Study found that people with vitamin D deficiency were more likely to
ovulate late compared to people with normal ovulation. I talk about that in this video
Does ovulating late make it more difficult to become pregnant? As long as you are attempting
pregnancy when you ovulate then people who ovulate late get pregnant at the
same rate as people who ovulate on time or early. However, over the course of a year,
people with late ovulation will have less opportunities to become pregnant.
Our InfertilityTV Bottom Line is this. About 10% of people will ovulate late,
on day 21 or beyond. If you fit into this group,
it is reasonable to see a fertility specialist to try to determine the possible reasons why