Tan asked
Hi there. I finished my last 21 day pill pack(Primabela) on 19 April. I was due to start my new pack on 27 April. I didn't get my pill in time and missed the first 4 pills. (Friday, Saturday, Sunday and Monday). I started taking my pills on the Tuesday and continuing my pack as normal. My husband and I had unprotected sex on the Fri 27 April, again on the Tues or Wed and multiple time from then, almost every day. I didn't take any emergency contraception or use any back up methods. If I am pregnant, when will I be able to get an accurate test? At the end of my pill pack next week? I have 9 more pills left of this pack. I don't know when I could have ovulated if I did.
Answer
All home pregnancy tests (such as First Response) test for levels of hCG (human chorionic gonadotropin) in the urine.
After a fertilized egg implants in the uterus, hCG levels start to increase. When you will test positive for pregnancy depends on the sensitivity of the test you are using, as some are more sensitive than others (i.e. can detect lower levels of hCG). In general though, pregnancy tests will begin to work about 3 days before a missed period, with accuracy increasing the closer you test to the usual day you get your period.
In relation to taking birth control pills, you would then begin to be able to test positive on pregnancy test on your last few days of your active (i.e. hormone containing) pills.
When Do Pregnancy Tests Work?
Most tests have a sensitivity for hCG at levels of 25 mIU/mL or higher. Studies show that with these tests, accuracy rates for a positive result are as follows:
- 52% three days before a missed period
- 69% two days before a missed period
- 86% one day before a missed period
Therefore a majority of woman will test positive for pregnancy up to three days before a missed period. Nevertheless, the closer you are to your usual time of menses, the more accurate the pregnancy test will be. Some studies show that testing 1 to 2 days after your missed menses is over 95% accurate.
As mentioned above, over the counter pregnancy tests have different sensitivity levels for hCG. Some also test for variations of hCG such as hCG-h, beta-hCG. These tests may provide positive results more than 3 days before a missed period. One such product is the First Response Early Result test, which has about a 76% accuracy rate 5 days before a missed period.
It is important to note that all individuals are different and may produce different amounts of hCG after implantation. In fact, nearly 10% of women don't produce enough hCG to be detected until a week or so after a missed period.
If you took a test that returned a negative pregnancy result but still have not had you period, it is recommended to retest or see your doctor for a more conclusive test. Lastly, for the most accurate results, test your urine in the morning as it will be the most concentrated.
How Missing Birth Control Pills Affects Pregnancy Chances
Not taking birth control pills consistently increases the risk of unplanned pregnancy. Although different products have different recommendations when it comes to missed doses, missing more than 3 doses of most products will result in the recommendation to start a new pack. In addition, you won't be protected from pregnancy until you take 7 days in a row of active pills.
As discussed above, pregnancy tests will being to work about 3 days before a missed period, or when you have about 3 active pills left in your birth control pack, but some tests are accurate up to 6 days before a missed period.
