What about birth control?
We get it - you’re young, not really thinking about having kids any time soon, and so you’re on birth control. Can you still test?
Short answer: yes. You can test if you have a normal amount of eggs for your age, and you can test if you’re at risk of blocked tubes.
Longer answer: yes, but you’ll have to remember that there’s a lot of factors that we can’t say anything about. We can’t test your ovulation, we can’t test your thyroid, and we can’t test your testosterone levels.
First up - what we can test:
We test: AMH
AMH is the most reliable indicator we have for ovarian reserve, but it’s not perfect. There hasn’t been enough research done on the exact impact of birth control on AMH levels, but we usually recommend women to keep a 15% margin in mind.
There hasn’t been a meta-study done to compare all studies of birth control on AMH, but the largest to date is a 2015 study on 887 women (Birch Petersen et al, 2015). They found that AMH levels for women who use ‘all forms of contraceptives’ are 19% lower than women who don’t use contraceptives. According to De Vries et al (2001) there’s no evidence that using the pill has any effect on when you’ll enter menopause, and so we can assume that the 19% dip is temporary.
We typically recommend women who find extremely low AMH values whilst on birth control to stop contraceptives for a while, wait until they have at least 2 ‘natural’ periods, and then retest to get a clearer picture.
We test: Chlamydia IgG
Chlamydia IgG is an indicator of the antibodies that you'll still have in your blood if you had a chlamydia infection. It doesn't matter if that infection happened a long time ago or if it's more recent, the antibodies will stay in your blood. This isn't in any way affected by your birth control, and so we can still test.
90% of chlamydia infections in women give no symptoms at the time, but they do cause scarring around the fallopian tubes. If your tubes are blocked, your fertilised egg can't get to the womb, en so you can't get pregnant. 60% of all blocked tubes are because of chlamydia infections. The good news: IVF is extremely successful for women who suffer from blocked tubes. The bad news: women often try to get pregnant naturally for a long time before they figure out this is up.
Then - what we can't test:
We test: LH, AMH, T
If you’ve read our science page, then you know that one of the main reasons why women end up at fertility clinics with problems is because their ovulation doesn’t work properly. Most hormonal birth control works by suppressing your ovulation (because: if you don’t release an egg every month, then you sure won’t have a baby). For obvious reasons, this means that if you don’t ovulate, we can’t test your ovulation. Some forms of birth control, such as for instance hormonal IUDs, work on a very low amount of locally applied hormones. This means that sometimes women still have periods (and also ovulate) when they’re on hormonal birth control. There's not been conclusive evidence to suggest that we can draw any conclusions from your ovulations on hormonal birth control, and so we've chosen not to test. Thyroid function We test: TSH
Your birth control also affects your thyroid function. A 2003 study by Wiegratz et al on 100 women found that there's a 'significant rise' in your TSH levels when you're on the pill. Some more recent studies suggest that TSH levels are more stable, but given that we don't have any solid data on what your contraceptive does to your levels, we don't want you to pay for a test that you don't need. If you're worried about your thyroid, we recommend you to always talk to your doctor before you change anything about your contraceptive. Certain contraceptives (most notably the combination pill) help stabilise your thyroid function. If you have any questions about this, email us on firstname.lastname@example.org.
We test: total T
You guessed it - your testosterone levels get impacted by your contraceptive. Zimmerman et al (2014) found in a study on 1495 women that your T values are on average 61% lower when you're on birth control. We mainly use testosterone to figure our if you're at risk of PCOS. PCOS is usually associated with high testosterone, and we'd worry about giving you a false safety if we tested whilst you were on birth control.