From the Guidelines
A pregnancy is confirmed when the serum human chorionic gonadotropin (hCG) value is greater than 5 mIU/mL, as stated in the most recent study from 2024 1. To confirm pregnancy, a combination of methods can be used, including home pregnancy tests, blood tests, and ultrasound imaging. Home pregnancy tests detect the hormone hCG in urine and are most accurate when used first thing in the morning and at least one day after a missed period.
- For the most reliable results, follow the package instructions carefully and wait the full recommended time before reading the result.
- If the test is positive, schedule an appointment with a healthcare provider for confirmation and prenatal care.
- If negative but you still suspect pregnancy, wait a few days and test again as hCG levels may not be high enough for detection early on. Blood tests at a medical facility can detect pregnancy earlier than urine tests and provide more definitive results, with a serum hCG value greater than 5 mIU/mL confirming pregnancy 1.
- Physical symptoms like missed periods, breast tenderness, nausea, and fatigue may suggest pregnancy but aren't conclusive on their own.
- Early confirmation is important to begin appropriate prenatal care and make informed health decisions. Ultrasound imaging, particularly transvaginal ultrasound, can also confirm pregnancy by visualizing the gestational sac, yolk sac, and embryo, with cardiac activity observed at around 6 weeks gestational age 1.
- The presence of a gestational sac, yolk sac, and embryo, along with cardiac activity, confirms a definite pregnancy.
- The crown-rump length should be used for dating as soon as an embryo is measurable, as it is more accurate than the mean sac diameter 1.
From the Research
Confirmation of Pregnancy
The confirmation of pregnancy is typically done through the detection of human chorionic gonadotropin (hCG) in urine or blood. The following are some key points to consider:
- hCG is an ideal marker of pregnancy as it rises rapidly and consistently in early pregnancy and can be detected in urine 2, 3, 4, 5, 6
- Pregnancy tests using antibodies to detect hCG are widely used and have become the most common diagnostic assay used at home 3
- The sensitivity and specificity of pregnancy tests have improved over the years, with most current tests having a sensitivity of 25 units per litre or higher 2, 4, 6
- Home pregnancy tests can detect pregnancy as early as 9-10 days post-conception and can give positive results at the time of the expected onset of menses in a significant percentage of cases 6
- The use of hCG tests in conjunction with ultrasound examination and laparoscopy can help diagnose ectopic pregnancy 5
Detection Methods
Some common methods used to detect pregnancy include:
- Urine tests using monoclonal antibodies to detect hCG 2, 3, 4, 6
- Blood tests to measure hCG levels 5
- Ultrasound detection, although not as sensitive as hCG measurement 2
- Home pregnancy tests, which are widely available and have varying levels of sensitivity and specificity 3, 4, 6
Sensitivity and Specificity
The sensitivity and specificity of pregnancy tests can vary depending on the type of test and the individual's hCG levels. Some key points to consider:
- The sensitivity of home pregnancy tests can range from 5.5 mIU/mL to 22 mIU/mL or higher 4
- The specificity of pregnancy tests is generally high, with false positive results due to interfering materials being extremely unlikely 2
- The use of highly sensitive hCG tests can detect small amounts of hCG early in pregnancy, but may not distinguish between intrauterine and ectopic pregnancy 5