It's common to have doubts about the reliability of a pregnancy test, especially if the woman shows signs of being pregnant but the result is negative.
In this situation, it´s normal for a woman to wonder if it´s possible for the test to show a negative result even though she actually is pregnant. This type of result is known as false negative and yes, it´s possible to occur in pregnancy tests
Below you have an index with the 8 points we are going to deal with in this article.
Pregnancy tests, tested both in urine or in blood, measure the human chorionic gonadotropin (hCG) hormone. This hormone is characteristic of pregnancy, as it´s secreted by the embryo in large quantities. Typically, hCG levels double every 48-72 hours in the first trimester of pregnancy. This increase in hCG levels in the mother's body is responsible for the appearance of typical pregnancy symptoms.
Among the functions of hCG one of them is to prevent the disintegration of the ovarian corpus luteum so that it continues to produce progesterone. In addition, hCG is involved in immune tolerance during pregnancy, protecting the early fetus from immune rejection. However, hCG secretion begins to progressively decrease at about 3 months of gestation.
If you want to know more about the pregnancy hormone, you can click here: What Are Normal hCG Hormone Levels during Pregnancy?
False negative pregnancy test
The blood pregnancy test has a higher sensitivity than the urine pregnancy test. This means that the blood test can detect smaller amounts of hCG hormone, so the likelihood of a false negative is lower in this type of test.
Causes of a false negative
The reasons for a false negative pregnancy test are:
- The test has been done too early: if at least 8-12 days have not passed since ovulation or there is no delay in menstruation, it´s quite possible that the hormone levels are not high enough to be detected by the test.
- The test has not been done with the first urine of the day: if a urine pregnancy test is done, it´s important to do it with the first urine of the day because it´s the one that contains the highest concentration of the hCG hormone.
- The woman is taking or has taken any medication that may affect the result.
- The test chosen is of low sensitivity, for example, it detects hCG levels above 20 mIU/ml. This means that the test will not be able to detect pregnancy at an early stage.
- Early pregnancy loss.
- The pregnancy test is expired or damaged.
In case any of these situations occur, the best way to check whether or not there is indeed a pregnancy is to repeat the test 2-3 days later to confirm the result.
Why do I feel pregnant if I am not?
As mentioned above, a woman can feel pregnant and have negative pregnancy tests. However, if symptoms of pregnancy persist and doubt remains, the woman should consult her physician.
The doctor will order an hCG blood test to confirm whether or not there is a pregnancy and will perform a transvaginal ultrasound to directly observe the inside of the uterus to look for the gestational sac and embryo. Furthermore, the specialist should also perform a physical examination and check the size of the uterus.
In case the doctor rules out pregnancy, the woman could be facing a psychological pregnancy. The causes of this type of pregnancy can be diverse, such as, for example, the woman has a very strong desire to become a mother or an atrocious fear of pregnancy.
Symptoms of psychological pregnancy include:
- Lack of menstruation (amenorrhea).
- Increase in breast size, aureole and breast pigmentation.
- Darkening of the skin.
- Increase in the size of the abdomen.
- Significant weight gain, more than in a normal pregnancy, and strong increase in appetite.
- Appearance of nausea and gastric problems such as heartburn.
- Presence of sleep disorders.
The physician may request additional tests to verify that these symptoms are not due to some other disorder and to confirm that it is indeed a psychological pregnancy. If this diagnosis is confirmed, the woman will need to start psychological therapy. The specialized professional may consider necessary the administration of medication, as well as working at home with the couple to overcome it.
If you want to know more about psychological pregnancy, you can access this article: What Is a False Pregnancy or Pseudocyesis?
Other causes of menstrual delay
Once the possibility of pregnancy has been ruled out, delays in the menstrual period indicate the presence of irregularities in the menstrual cycle. These irregularities can occur in all women at some point in their lives.
The reasons for a menstrual delay can be varied:
- Polycystic Ovaries
- women with polycystic ovary syndrome may have infrequent or prolonged menstrual periods, have excessive levels of male hormone (androgen), and their most frequent symptoms are hirsutism (excess hair), centripetal obesity, and menstrual irregularity. It is one of the most common disorders in women and its prevalence is estimated between 5 and 20%.
- Change of habits
- time changes can influence the hormonal cycle. Women who make drastic dietary changes, severe exercise practice or a major emotional life change may have irregular cycles. Therefore, it´s important to maintain an adequate and balanced dietary habit.
- is one of the main enemies because it affects the production of cortisol, increasing its levels. This increase is reflected in subsequent estrogen and progesterone production, again explaining menstrual delays and the presence of nausea.
- Thyroid hormone alterations
- too much (hyperthyroidism) or too little (hypothyroidism) thyroid hormones results in problems in achieving or carrying a pregnancy to term, miscarriages, pregnancy problems or premature delivery. In addition, these alterations are associated with anovulation and abnormal menstrual cycles.
- the intake of certain medications can cause amenorrhea (absence of menstruation). Some examples could be antipsychotics, antidepressants and poor oral contraceptive intake.
- Assisted reproduction treatments
- in these patients, the use of vaginal progesterone sometimes delays menstrual bleeding. In addition, it can cause a delay in bowel emptying, resulting in nausea and emotional changes that are often mistaken for pregnancy symptoms.
Assisted procreation, as any other medical treatment, requires that you rely on the professionalism of the doctors and staff of the clinic you choose. Obviously, each clinic is different. Get now your Fertility Report, which will select several clinics for you out of the pool of clinics that meet our strict quality criteria. Moreover, it will offer you a comparison between the fees and conditions each clinic offers in order for you to make a well informed choice.
As we have just seen, there are many causes that can lead to a delay in menstruation. Therefore, if you have any doubts, don´t hesitate to contact a specialist
FAQs from users
Can PCOS give a false positive pregnancy test?
Pregnancy tests determine the presence in a woman's urine of a hormone (beta-hCG= beta chorionic gonadotropin unit) which is produced when pregnancy occurs. A positive test means that this hormone is present in the woman's urine and therefore a pregnancy.
Polycystic ovary syndrome (PCOS) is when the ovaries produce higher than normal amounts of androgens and this can interfere with the development and release of the egg. Sometimes, instead of eggs forming and maturing, cysts develop in the ovaries. Instead of being released during ovulation, as the egg is released during a normal menstrual cycle, the cysts grow and increase in size.
Only in the case of a cyst that produces hCG, which is very rare, the hormone would show in your urine and give a false-positive result with the pregnancy test.
Can a pregnancy test fail?
Yes, the negative result can be wrong. The main reason is usually that the pregnancy test has been done too soon, but, as indicated in the article, it can happen because the test is in poor condition, because it is not highly sensitive or because there has been an early abortion, among other things.
I think I'm pregnant but the test is negative, what's wrong with me?
Don't worry, everything is fine with you. Just repeat the test in about a week to confirm the result. If it's still negative, it's very likely that the symptoms you notice are due to another reason, not a pregnancy. If you are in doubt, it is best to contact your doctor for an ultrasound and an exploration, although if the pregnancy is very early you will not be able to see anything on the ultrasound and you should wait a few weeks.
How do I know if I'm pregnant if my test shows negative?
The first thing would be to repeat the pregnancy test after about 5 days. If the test continues to be negative, it is more likely that your period will come soon, but if it does not, it is best to consult your doctor.
Is the result of a negative urine pregnancy test before the delay in menstruation reliable?
It depends on the sensitivity of the test, i.e. the minimum amount of hCG hormone it can detect. However, for the result to be reliable, it's recommended to perform the pregnancy test once there is a missed period. This means that you should wait to take the test until there is a delay in your period with respect to the day you expected it to come. In this way, false negatives are avoided because the hormone should already be at levels detectable by the test.
Therefore, in this situation, we recommend repeating the test on the appropriate days to obtain a more reliable result.
If you want to know more about pregnancy symptoms, we recommend you visit this link: What Are the Most Common Symptoms of Pregnancy?
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Azizi M, Elyasi F. Biopsychosocial view to pseudocyesis: A narrative review. Int J Reprod Biomed. 2017 Sep;15(9):535-542.
Cole LA. The hCG assay or pregnancy test. Clin Chem Lab Med. 2012 Apr;50(4):617-30.
Dabadghao P. Polycystic ovary syndrome in adolescents. Best Pract Res Clin Endocrinol Metab. 2019 Jun;33(3):101272.
Deligeoroglou E, Creatsas G. Menstrual disorders. Endocr Dev. 2012;22:160-170.
Foster C, Al-Zubeidi H. Menstrual Irregularities. Pediatr Ann. 2018 Jan 1;47(1):e23-e28.
Griffey RT, Trent CJ, Bavolek RA, Keeperman JB, Sampson C, Poirier RF. "Hook-like effect" causes false-negative point-of-care urine pregnancy testing in emergency patients. J Emerg Med. 2013 Jan;44(1):155-60.
Montagnana M, Trenti T, Aloe R, Cervellin G, Lippi G. Human chorionic gonadotropin in pregnancy diagnostics. Clin Chim Acta. 2011 Aug 17;412(17-18):1515-20.
Tarín JJ, Hermenegildo C, García-Pérez MA, Cano A. Endocrinology and physiology of pseudocyesis. Reprod Biol Endocrinol. 2013 May 14;11:39.
Theofanakis C, Drakakis P, Besharat A, Loutradis D. Human Chorionic Gonadotropin: The Pregnancy Hormone and More. Int J Mol Sci. 2017 May 14;18(5):1059.
Upadhyay S. Pseudocyesis. JNMA J Nepal Med Assoc. 2008 Jul-Sep;47(171):147-50.
FAQs from users: 'Can PCOS give a false positive pregnancy test?', 'Can a pregnancy test fail?', 'I think I'm pregnant but the test is negative, what's wrong with me?', 'How do I know if I'm pregnant if my test shows negative?' and 'Is the result of a negative urine pregnancy test before the delay in menstruation reliable?'.
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