Home pregnancy tests detect the presence of a specific pregnancy hormone present in urine and are, according to the American Pregnancy Association, 97 percent accurate when taken correctly. Part of taking them correctly is taking them at the right time. If taken too early, the test could yield a false negative. In order to determine when the proper timing is for a home pregnancy test, a woman must calculate when she should have begun menstruating.

Things You Will Need

Pencil and paper
Home pregnancy test

Step 1

Write down the date of the first day of your last menstrual period. According to Teen Health.org, the average menstrual cycle length is 21 to 45 days. This is the starting point for calculating your fertile dates and the dates when you can take a home pregnancy test.

Step 2

Count forward 14 days if you know you have a regular 28 day cycle. The three days before this date to the three days after this date are the days you're most likely to be fertile, however fertile days differ from woman to women and cycle to cycle. Ovulation usually occurs in the middle of a woman's menstrual cycle or two weeks before menstruation for irregular length cycles. Count forward 15 days from your estimated ovulation date (or 29 days from the first day of your last cycle for regular 28 day cycles) to determine the date you can first take a pregnancy test. According to The American Pregnancy Association, urine tests are most accurate at least one day after a missed period.

Step 3

Calculate when to take a pregnancy test for irregular cycles by first recording what information you know about your previous cycle. Write down which days you had unprotected intercourse, which days you showed signs of ovulation, like egg-white discharge, and write down the date of your last menstrual cycle. Calculating when to take a test for these cycles can be more difficult. According to Baby Center.com, it takes approximately two weeks after unprotected intercourse for urine pregnancy tests to accurately display a positive result. Count forward 14 days from the dates of unprotected intercourse and take your test then. If you've had unprotected sex on multiple occasions, take a test weekly until you get your period or until it has been three weeks or more since your last unprotected sex. Test the third week after your last unprotected intercourse in case your two week test yielded a false negative. This can happen if your hormonal levels aren't yet strong enough in your urine to produce a positive result.

Step 4

Wait a week before taking another test if your first test was negative. This will give the pregnancy hormones time to build to detectable levels in your body and save you from spending extra money on pregnancy tests. According to the American Pregnancy Association, some tests are more sensitive than others. Women's bodies produce pregnancy hormones at different rates.

Step 5

Schedule an appointment with your doctor for a blood test if your home pregnancy test or tests were negative, but you still haven't gotten your period, or if you show other signs of pregnancy, like breast tenderness or nausea. There's no set time frame for scheduling an appointment with your doctor. Women who want to know right away can schedule appointments as early as a day ofter a missed period. Your health care provider may recommend you wait one to two weeks to see if your period arrives. Array

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