Ovulation prediction kits are now widely available and
reasonably inexpensive, so they have become popular with many women
planning to fall pregnant.
There are three main types of ovulation predictor.
The primary tests are two which are used at home. The most
common and easiest to use is a urine test called an ovulation
prediction kit (OPK), while the second
type, a saliva ovulation test, uses a special microscope to detect
a hormonal change in saliva.
The third type of ovulation predictor is a series of blood
tests, which you may decide to arrange through your doctor if you
are having trouble identifying your fertile period.
What does an ovulation predictor measure?
Just before ovulation occurs, there is a significant rise in the
level of certain hormones, including oestrogen and luteinising
hormone (LH).
The advantage that an ovulation predictor test has over some of
the other methods of measuring ovulation, is that it can detect the
rise in hormones that occurs in the lead up to ovulation.
Using the rise in your basal body temperature that occurs after
ovulation, as a measure of ovulation, will only give you
information after you have ovulated.
Little of your body's fertile time remains after ovulation. So
the ovulation temperature technique is only useful if you are
trying to chart a pattern of ovulation over a number of months.
However, an ovulation predictor will often give a result between
one and two days before ovulation, and so - theoretically - you are
able to ensure that intercourse occurs at your most fertile
time.
How accurate is an ovulation predictor?
There is very solid research behind everyday ovulation
prediction kits, and advances in medical technology have made these
kits easier and cheaper to manufacture, and therefore widely
available.
However, one of the drawbacks of an ovulation predictor is that
the rise in hormone levels may occur several times before the egg
is released.
It is reasonably common for an ovulation predictor to give a
"false positive" result. The result, while accurately reflecting
the presence of a high level of hormones, does not necessarily mean
that ovulation has occurred.
Urine tests - Ovulation predictor kits (OPKs)
An ovulation predictor kit (OPK)
operates in a very similar way to a home pregnancy test.
These kits test for the presence of luteinising hormone (LH) in
the urine, which occurs between 24 and 48 hours before the release
of the egg.
While each kit may have a slightly different methodology, the
kits usually require you to use them daily (generally first thing
in the morning is best) for around a week at the time that you
estimate will be your most fertile time.
Ironically, women who have irregular cycles - and therefore are
most likely to need to use an OPK to
assist them to predict the time of ovulation - usually find the kit
is less accurate to use because of the variability in their fertile
period.
One solution offered by OPK
manufacturers for those with irregular cycles, is to use the kit
more frequently throughout the cycle. However, this is a more
costly option.
Most kits supply between five and 12 individual tests, however
it is possible to buy the tests in bulk in some places.
Saliva Ovulation test
Another hormone which increases just before ovulation is
oestrogen; and the presence of oestrogen causes a slight change in
the structure of saliva, involving an increase in its salt
content.
This increase in salt in saliva as a result of higher levels of
oestrogen can be detected quite easily under a microscope because
the salt-laden saliva crystallises into a fern-like pattern when it
dries, unlike the usual shapeless, dotted pattern that saliva
usually dries into.
Saliva ferning can be identified from around four days before
ovulation, and is also present for about two days after ovulation.
For this reason, it is important to test daily during the first
part of the woman's cycle.
Although most optical microscopes, at the correct setting, could
theoretically detect this pattern, unless you have expertise with
the use of microscopes, it is probably worth investing in a
specialist mini-microscope designed to detect saliva patterns.
The saliva ovulation predictor test requires the user to develop
a certain level of familiarity with patterns of saliva and can be a
little fiddly.
However, although there is an initial investment in the purchase
of the device, there are no ongoing costs, so this can be quite an
economical way of identifying your fertile period.
Blood Tests
Regular blood tests taken every few days during your cycle can
give more accurate measures of the quantity of hormones present at
different stages of your cycle.
These tests are usually organised through your general
practitioner or a fertility specialist.
Because they are more invasive than testing urine or saliva,
blood tests would not normally be done unless other methods of
identifying ovulation had been attempted first.
There are a number of conditions, some easily treated, which can
interfere with fertility because your body is not producing the
appropriate amounts of hormones at certain stages of your
cycle.
Issues such as thyroid or endocrine problems (such as polycystic
ovary syndrome, which affects between five and twelve percent of
women and is one of the leading known causes of infertility) can be
treated using drugs to stimulate ovulation.
Obviously, it's really important to get tests to confirm an
accurate diagnosis of any condition before undergoing
treatment.
By Fran Molloy, journalist and mum of four