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Pregnancy Tests

Osher Ben Or, Certified Midwife
13 June 2024
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Whether you are curious or have a suspicion that you want to check as soon as possible, it is now possible to determine pregnancy very early, in the very first days. An early detection of pregnancy plays an important role because it allows for more accurate monitoring of your pregnancy progression and adjustment of your lifestyle to the new condition. If it is an unwanted pregnancy, early detection will allow you to make an informed decision at the very beginning.

Pregnancy test types and when to get tested

Home pregnancy test: a home pregnancy test is available in every pharmacy, and it involves a simple urine test. However, taking the test too early in the pregnancy may yield a negative result despite the development of the pregnancy. Nevertheless, it is important to note that a urine test is highly sensitive, and a positive result is considered reliable. You can perform a urine test to determine pregnancy on the first day after a missed period.

Blood test: blood tests offer a more reliable method for early pregnancy detection as they measure the hCG hormone in the blood (beta), which can be detected about 10 days after conception. However, it is important to note that very low levels of hCG in an extremely early pregnancy may not be detectable with this method. Therefore, for a higher level of certainty, it is recommended to perform the test on the day your period was expected or one or two days later.

Blood tests to detect a pregnancy can be performed at your HMO. The test is free of charge, but you will need a referral letter from your physician.

The importance of monitoring the level of blood hCG

Most normal pregnancies do not necessitate monitoring. However, on rare occasions, or when there is a discrepancy between the anticipated pregnancy week and the ultrasound findings at your gynecologist, monitoring your hCG level may be essential. A slower rise in hCG levels than expected can indicate a potential complication, such as an ectopic pregnancy. Conversely, a low hormone level might indicate an error in the gestational age calculation. On the other hand, elevated hCG levels may raise suspicions of a multiple pregnancy or an abnormal pregnancy.

A single test result is insufficient to provide the necessary data needed to diagnose a pregnancy-related issue. Therefore, monitoring hCG levels through serial blood tests is crucial. Generally, at least two blood tests are necessary, with an interval of two days between them.

From the sixth pregnancy week, the normality and progression of pregnancy are determined through ultrasound examinations. Therefore, after receiving the pregnancy test result, you will have to schedule an appointment with your gynecologist to confirm your pregnancy and determine the gestation age.

An early detection of pregnancy is possible, and it plays an important role as it allows for better monitoring of the pregnancy’s normality and development. It provides an opportunity for adopting a healthy lifestyle and making necessary adjustments during pregnancy. Early detection also provides you with the opportunity to make informed decisions at the beginning of the pregnancy.

From the very beginning of pregnancy, your body undergoes changes intended to support the fertilized egg. One of these changes is the production of a hormone called human chorionic gonadotropin, or hCG. Every pregnancy test available today is designed to detect the presence of hCG in your blood.

Pregnancy tests are based on urine tests for confirming the presence of hCG or, conversely, a blood test that measures the levels of hCG.
The hCG hormone molecules comprise of two units, alpha and beta. The blood test measures only the beta unit: the β hCG.

What is the hCG hormone

The hCG hormone is produced by the placenta shortly after the fertilized egg implants in the uterine lining (the endometrium). Its level rapidly increases during the initial stages of pregnancy, reaching its peak around 8 weeks after conception. If fertilization and implantation have occurred, hCG can be detected in your blood approximately 6 to 10 weeks after ovulation.

The level of the hCG hormone is supposed to double every 48 to 72 hours during the initial stages of pregnancy. Its level continues to rapidly increase, reaching its peak around 9 to 12 weeks into the pregnancy, and then it starts to subside gradually. Around the 20th week, the hormone reaches its lowest level and maintains this level until birth.

The role of the hCG hormone

The role of the hCG hormone is to prevent the corpus luteum from degenerating so that it continues producing progesterone that supports the developing pregnancy. If the corpus luteum degenerates, the level of progesterone decreases, leading to the disintegration of the uterus lining.

During the 6th to 14th days of the menstrual cycle, which typically lasts around 28 days, the uterus lining is constructed, widens, and prepares for the potential implantation of a fertilized egg. Then, around the 14th day of the menstrual cycle, ovulation occurs. After ovulation, the corpus luteum is formed.

The corpus luteum is a temporary endocrine structure whose role is to secrete progesterone, which helps widen the uterus lining and prepare it for the implantation of the fertilized egg, and later, to support the pregnancy until the placenta develops and secrete the hormones themselves. If the egg does not become fertilized, the corpus luteum degenerates, leading to a sharp fall in the level of hormones. This sharp fall in hormone levels causes the lining of the uterus to shed during menstruation.

When should you take a pregnancy test

If you suspect you may be pregnant or experience early pregnancy symptoms, consider taking a home pregnancy test. However, bear in mind that a negative result could be due to testing too early. For reliable confirmation, it is advised to undergo a blood test for β-hCG.

Blood tests offer a more sensitive approach to early pregnancy detection compared to home urine tests. Their ability to measure extremely low levels of hCG allows for accurate results even in the early stages of pregnancy.

A blood test is a quantitative test that yields a numerical value of the hormone’s presence in the blood. Conversely, a urine test is a qualitative test that determines the presence of the hormone and delivers either an affirmative or a negative result.

A variety of pregnancy tests exists on the market. The primary distinctions between them are the cost, the level of sensitivity (the number of days after ovulation in which the test can detect a pregnancy), and the method of testing. However, the principle is identical: all the tests inspect the presence of the hCG hormone in the urine.

The higher the level of the blood hCG hormone, the higher it will be in the urine. Keep in mind that if you take the pregnancy test too early, it may produce a negative result despite the development of the pregnancy.

A urine test can detect a pregnancy as early as two days before a missed period. However, it is recommended to perform the test on the day your period is expected or one or two days later. If the urine test yields a positive result, it is advised to schedule an appointment with your gynecologist for an ultrasound examination to determine the gestational age.

How to perform a home pregnancy test

  • Ensure that the home pregnancy test is valid. Check the external packaging for the validity date and avoid purchasing tests that have expired.
  • Carefully review the instructions. Check where to drip the urine or, alternatively, on which side of the stick the urine should be immersed. Observe the recommended waiting time before interpreting the result, and understand how positive and negative results are indicated, among other details.
  • When to conduct the test: it is advised to take the test using the first morning urine, as it is more concentrated and can yield higher hormone levels.
  • Conducting the test: follow the instructions: either urinate into a cup and dip the stick in the cup or use a dropper to drop urine from the cup directly onto the stick, and be sure to read the instructions carefully.
  • Reading the result: after waiting a few minutes, you will receive the result, which includes specific signs that indicate pregnancy. Follow the manufacturer's instructions for the meaning of each sign.
  • Remember: if you conduct the pregnancy test according to the instructions and at the appropriate time, when it is possible to detect the hCG hormone, the result will be reliable.

The advantages of a home pregnancy test

A home pregnancy test is available in every private or public pharmacy. It is easy to use, and it usually provides a quick result. The manufacturers of pregnancy tests claim a certainty of 98% in detecting a pregnancy when the test is used correctly and according to the instructions.

Disadvantages: compared to blood tests, which are free under most HMOs, home pregnancy tests need to be purchased, sometimes multiple times. Additionally, home pregnancy tests are less sensitive than blood tests. It makes the timing of the test, which provides a qualitative result, highly significant. Furthermore, false negatives can occur if the test is taken too early.

Conditions that may impact the test result

The outcome of a urine or blood test can bring either joy or disappointment. Yet, over time, it may become apparent that the happiness arrived prematurely or that the disappointment was unwarranted. It is important to consider factors that can bring to a false positive result.

If you take fertility drugs that contain the hormone hCG (such as Ovidrel and Pregnyl), you may see a positive result that will turn out inaccurate. The same may happen in a chemical pregnancy, which starts in the first few weeks when hCG can be detected before a gestational sac is identified in the uterus on ultrasound. However, the pregnancy stops developing shortly after.
Conversely, a pregnancy test conducted too early in the pregnancy may not detect hCG in the urine and yield a false negative result.

Blood tests for detecting pregnancy are considered reliable and accurate. If necessary, these tests also allow for the monitoring of hCG hormone levels in the blood, commonly known as beta.

Conducting a blood pregnancy test requires a referral letter from your physician. You can take the test free of charge at the medical center performing lab tests at your HMO. A blood sample is drawn from a vein in your arm and sent for analysis.

The level of the hCG hormone is detectable in the blood within 10 days from the moment of conception. Therefore, the earliest time to detect pregnancy through a blood test of hCG is about 10 days after conception. However, low levels of the hormone in a very young pregnancy may not show up in the test at such an early stage. The ideal timing for taking a test to achieve a reliable result is the day the period would have appeared, or a day or two later.

The level of the hCG hormone varies from woman to woman. A level under 5mlU/ml is negative, and levels over 25mlU/ml are usually considered positive. However, there is no specific level that confirms or excludes pregnancy. The rise of the hCG hormone over time is more significant, consequently, in certain cases, an additional test will be required.

Monitoring the blood level of hCG

From the sixth week of pregnancy, the normality and progression of pregnancy are determined through ultrasound examinations. Therefore, after receiving the pregnancy test, you will have to schedule an appointment with your gynecologist to confirm your pregnancy and determine the gestational age.

It is recommended to schedule the appointment for the time you are expected to be in the sixth or seventh week of pregnancy, around two weeks after the time your period would have appeared. In this examination, the physician will also determine the location of the gestation sac, the number of embryos in the uterus, and check for a fetal heartbeat. In case no pregnancy is identified or there is another problem, you will be referred by your physician to monitor your hCG hormone levels in your blood.

Monitoring the beta level in your blood is performed to assess the course of pregnancy and its health. If a slower than anticipated rise in beta levels is identified, it may be a potential complication, such as an ectopic pregnancy. A low beta hCG level may also indicate an error in the gestation age calculation.

Conversely, a high hCG level may raise suspicion of molar pregnancy or multiple pregnancy.
One test result of the hCG hormone levels is not sufficient for obtaining the required information to diagnose problems. Therefore, monitoring the rise in hormone levels is needed. Usually, at least two blood tests are necessary, with an interval of two days between them.

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