Week 4 might be too early for a standard at-home pregnancy test to work with any accuracy. Pregnancy tests react to the pregnancy hormone Human Chorionic Gonadotropin (hCG) which starts being created once the fertilized egg turns into a blastocyst. Levels of this hormone double every 48 hours as the blastocyst embeds in the uterine lining and continue to increase until about ten weeks after fertilization.
While a standard test may not be able to answer your questions, an early response test kit might (woohoo!). The Clearblue Digital Pregnancy Test could potentially detect if you are pregnant a few days before you miss your period as it is more sensitive to the hCG hormone than some competing tests. Of course, these tests become more accurate as you approach the date of your next period and once that date has passed. These early response type tests can also provide a false negative, so you should retest after you miss your period as well. If the test remains negative after you've missed the due date for your monthly cycle, but you have PMS type symptoms like sore breasts, moodiness, or flu-type complaints, a blood test for hCG test can be done at your doctor's office or lab as prescribed by your caregiver. A blood test is more sensitive than the at-home urine test, but most doctors will still want you to wait until you've missed your period before offering a blood test for pregnancy confirmation. Of course, your specific situation and potential fertility interventions could mean frequent or sooner testing.
Often, the stress and anxiety of waiting for that positive sign could result in a missed or late period unrelated to a fertilized egg. Unfortunately, this late menstrual arrival could have you believing you're pregnant when you aren't. Because this is a potential occurrence, it is best to stay relaxed and practice patience when trying to conceive so you aren't disappointed.
This is a lecture-style informative video on what is happening during this time period.
- WebMD - Pregnancy Test and How They Work
- WebMD - Pregnancy Tests
- American Pregnancy - Understanding Pregnancy Tests: Blood and Urine