While ovulation generally occurs around day 14 of your cycle (roughly two weeks before your period, if you have a regular 28 day cycle), that's not always the case.
That's why ovulation kits can be an appealing option for those trying to pinpoint the ultimate time to fall pregnant.
That's what Tracy, 38, thought. After two months of trying to conceive with no results, she spoke to a friend who was in a similar boat. Her friend recommended a saliva ferning test.
Tracy was keen to give it a go and says the test was easy to use.
She explains you simply apply your saliva to a disc that is then magnified to show a result. She says the saliva must be "unaltered" (as in, no recent food intake, toothpaste or bubbles present).
The test wasn't only easy to use – Tracy also credits it for helping her fall pregnant on the first cycle she tried it.
"This provided the missing link as to why we weren't falling pregnant. It really was a timing thing for us," she says.
Fertility expert, obstetrician and gynaecologist Dr Alex Polyakov agrees ovulation tests can serve a useful purpose.
"I recommend ovulation tests, especially for people with slightly longer or irregular cycles," he says.
He says they're also useful when you're doing ovulation induction with Clomid, as cycles are usually a bit longer then, and predicting your fertility window can be tricky.
A saliva ferning test is based on the idea that when you're ovulating, your saliva, when magnified, produces a pattern that resembles a fern (yes, like the plant). This is based on changes in oestrogen levels.
"Increased oestrogen level results in higher sodium [salt] content in saliva and higher sodium is responsible for the ferning pattern," Dr Polyakov explains.
The problem with these kinds of tests, says Dr Polyakov, is that they rely on people having to identify a pattern.
Such tests may also not be useful for everyone, as "some women have elevated oestrogen and some don't".
Luteinising hormone (LH) tests
While Tracy opted for a saliva ferning kit, the other main form of ovulation test measures the amount of LH (luteinising hormone) present in the urine. LH peaks in the urine approximately one to one and a half days before ovulation.
These tests are performed in much the same way as a urine pregnancy test (by either peeing on a stick, or placing the stick in a cup containing urine). Results take a few minutes.
These kits, known as ovulation prediction kits (OPK), contain a few tests, allowing you to test these levels over several days.
Although these tests are easy to use, they're not always helpful, says Dr Polyakov.
"In some women LH levels are chronically elevated – this is especially true in PCOS [polycystic ovarian syndrome] patients. In these women testing will be constantly positive and may be useless and misleading."
Unfortunately, 29-year-old Andrea found that out firsthand.
After trying urine ovulation tests for eight months, Andrea was diagnosed with PCOS.
"The specialist identified that I probably had not been ovulating during those eight months, even though I had positive ovulation predictor kits!" she said.
Not only were the test results misleading, but they were also expensive, with Andrea estimating she spent "a good few hundred dollars on them".
When to get help
If you're worried you're not ovulating, or if you have other concerns, see your GP for a fertility assessment and referral to a gynaecologist if needed.
You may need further investigations if you've been trying to conceive through regular unprotected sex for more than 12 months if you're younger than 35, or more than six months if you're over 35.
While Tracy recommends ovulation tests ("It worked for us!"), Andrea now prefers a more laid-back approach.
She is still trying to conceive and believes ovulation tests definitely have a "place" and can help some women, but she's adopted a new attitude.
"I think the 'relax and enjoy it' approach to trying to grow your family is way more fun, romantic and special."